National Library of Energy BETA

Sample records for rpd-sc iot o-2

  1. IoT Interoperability at Bosch

    Broader source: Energy.gov (indexed) [DOE]

    Acquire d S oftwa re Innova tions , 2008 Bus ine s s proce s s ma na ge me nt Cloud-ba s e d IoT s olutions Acquiring P ros ys t (a nnounce d Fe brua ry 2015) P...

  2. Lawrence Co. Scioto Co. Greenup Co. Jack

    U.S. Energy Information Administration (EIA) Indexed Site

    CROOK PYR AMI D AU XIER LEF T F OR K B CUCU MBER CRK CHANEY CREEK DINGUS RPD-SC IOT O-3 MOORE BRANC H RPD-TAZ EWELL-1 PORT ER CAMP MOU SIE WILD CAT HOLLOW SPR ING CREEK RACCOON ...

  3. O2Purge.key

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Time ( 4/21/2015 t o 4 /24/2015) O 2 C ontamina4on o f G aseous A rgon D uring P urge 100--- 90--- 80--- 70--- 60--- 50--- 40--- 30--- 20--- 10--- O 2 C ontamina4on [ ppm]

  4. Instability of Hydrogenated TiO2

    SciTech Connect (OSTI)

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  5. O2Diesel Corporation formerly Dynamic Ventures | Open Energy...

    Open Energy Info (EERE)

    O2Diesel Corporation formerly Dynamic Ventures Jump to: navigation, search Name: O2Diesel Corporation (formerly Dynamic Ventures) Place: Newark, Delaware Zip: 19713 Product:...

  6. High thermal stability of La2O3 and CeO2-stabilized tetragonal ZrO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Shichao; Xie, Hong; Lin, Yuyuan; Poeppelmeier, Kenneth R.; Li, Tao; Winans, Randall E.; Cui, Yanran; Ribeiro, Fabio H.; Canlas, Christian P.; Elam, Jeffrey W.; et al

    2016-02-15

    Catalyst support materials of tetragonal ZrO2, stabilized by either La2O3 (La2O3-ZrO2) or CeO2 (CeO2-ZrO2), were synthesized under hydrothermal conditions at 200 °C with NH4OH or tetramethylammonium hydroxide as the mineralizer. From In Situ synchrotron powder X-ray diffraction and small-angle X-ray scattering measurements, the calcined La2O3-ZrO2 and CeO2-ZrO2 supports were nonporous nanocrystallites that exhibited rectangular shapes with thermal stability up to 1000 °C in air. These supports had an average size of ~10 nm and a surface area of 59-97 m2/g. The catalysts Pt/La2O3-ZrO2 and Pt/CeO2-ZrO2 were prepared by using atomic layer deposition with varying Pt loadings from 6.3-12.4 wt %.more » Mono-dispersed Pt nanoparticles of ~3 nm were obtained for these catalysts. As a result, the incorporation of La2O3 and CeO2 into the t-ZrO2 structure did not affect the nature of the active sites for the Pt/ZrO2 catalysts for the water-gas-shift (WGS) reaction.« less

  7. Compact Potentiometric O2/NOx Sensor | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    O2/NOx Sensor Compact Potentiometric O2/NOx Sensor 2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting PDF icon pm043_singh_2012_o.pdf More Documents & Publications Compact Potentiometric NOx Sensor Compact Potentiometric NOx

  8. Low Cost TiO2 Nanoparticles - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Solar Photovoltaic Solar Photovoltaic Advanced Materials Advanced Materials Find More Like This Return to Search Low Cost TiO2 Nanoparticles Sandia National Laboratories Contact SNL About This Technology Publications: PDF Document Publication Market Sheet (866 KB) TEM image of TiO<sub>2 </sub>nanoparticles taken at 50kx magnification demonstrates discrete and stable end product. TEM image of TiO2 nanoparticles taken at 50kx magnification demonstrates discrete and stable end product.

  9. Effects of CeO2 Support Facets on VOx/CeO2 Catalysts in Oxidative Dehydrogenation of Methanol

    SciTech Connect (OSTI)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Peden, Charles HF; Wang, Yong

    2014-05-13

    CeO2 supports with dominating facets, i.e., low index (100), (110) and (111) facets, are prepared. The facet effects on the structure and catalytic performance of supported vanadium oxide catalysts are investigated using oxidative dehydrogenation of methanol as a model reaction. In the presence of mixed facets, Infrared and Raman characterizations demonstrate that surface vanadia species preferentially deposit on CeO2 (100) facets, presumably because of its higher surface energy. At the same surface vanadium densities, VOx species on (100) facets show better dispersion, followed by (110) and (111) facets. The VOx species on CeO2 nanorods with (110) and (100) facets display higher activity and lower apparent activation energies compared to that on CeO2 nanopolyhedras with dominating (111) facets and CeO2 nanocubes with dominating (100) facets. The higher activity for VOx/CeO2(110) might be related to the more abundant oxygen vacancies present on the (110) facets, evidenced from Raman spectroscopic measurements.

  10. Hole Trapping at Surfaces of m?ZrO2 and m?HfO2 Nanocrystals

    SciTech Connect (OSTI)

    Wolf, Matthew J.; Mckenna, Keith P.; Shlyuger, Alexander L.

    2012-12-03

    We investigate hole trapping at the most prevalent facets of monoclinic zirconia (m-ZrO2) and hafnia (m-HfO2) nanocrystals using first-principles methods. The localization of holes at surface oxygen ions is more favorable than in the bulk crystal by up to ?1 eV. This is caused mainly by the reduction of the absolute value of the electrostatic potential at the surface ions with respect to the bulk and by the significant surface distortion caused by the hole localization. The mobility of holes at surfaces is much lower than that found in the bulk and is fairly isotropic. Unlike in cubic oxides, such as MgO and CaO, we do not find a significant driving force for preferential trapping of holes at steps on the m-ZrO2 surface. These fundamental results are relevant to mechanisms of water oxidation, photocatalysis, contact charging, and photodesorption.

  11. trans-K3[TcO2(CN)4

    SciTech Connect (OSTI)

    Chatterjee, Sayandev; Del Negro, Andrew S.; Edwards, Matthew K.; Twamley, Brendan; Krause, Jeanette A.; Bryan, Samuel A.

    2010-07-14

    The dioxotetracyanotechnetate anion, [TcO2(CN)4]3-, of the title complex has octahedral symmetry. The technetium is located on a center of inversion and is bound by two oxygen atoms and four cyano ligands. The Tc?O bond distance of 1.7721 (12) is consistent with double bond character. The potassium cations [located on special (1/2,0,1) and general positions] reside in octahedral or tetrahedral environments; interionic KO and KN interactions occur in the 2.7877 (19)-2.8598 (15) range.

  12. Highly-Selective and Reversible O2 Binding in

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cr3(1,3,5-benzenetricarboxylate)2 | Center for Gas SeparationsRelevant to Clean Energy Technologies | Blandine Jerome Highly-Selective and Reversible O2 Binding in Cr3(1,3,5-benzenetricarboxylate)2 Previous Next List Leslie J. Murray, Mircea Dinca, Junko Yano, Sachin Chavan, Silvia Bordiga, Craig M. Brown and Jeffrey R. Long, J. Am. Chem. Soc., 2010, 132 (23), pp 7856-7857 DOI: 10.1021/ja1027925 Abstract Image Abstract: Reaction of Cr(CO)6 with trimesic acid in DMF affords the metal-organic

  13. Atmospheric Pressure Chemical Vapor Deposition of High Silica SiO2-TiO2 Antireflective Thin Films for Glass Based Solar Panels

    SciTech Connect (OSTI)

    Klobukowski, Erik R; Tenhaeff, Wyatt E; McCamy, James; Harris, Caroline; Narula, Chaitanya Kumar

    2013-01-01

    The atmospheric pressure chemical vapor deposition (APCVD) of SiO2-TiO2 thin films employing [[(tBuO)3Si]2O-Ti(OiPr)2], which can be prepared from commercially available materials, results in antireflective thin films on float glass under industrially relevant manufacturing conditions. It was found that while the deposition temperature had an effect on the SiO2:TiO2 ratio, the thickness was dependent on the time of deposition. This study shows that it is possible to use APCVD employing a single source precursor containing titanium and silicon to produce thin films on float glass with high SiO2:TiO2 ratios.

  14. Valence electronenergy-lossspectroscopystudyofZrSiO4 and ZrO2...

    Office of Scientific and Technical Information (OSTI)

    electronenergy-lossspectroscopystudyofZrSiO4 and ZrO2 ZrSiO4 (zircon) and m-ZrO2 (zirconia) are fundamental and industrially important materials.This work reports the detailed...

  15. Low Temperature Autoignition of C8H16O2 Ethyl and Methyl Esters...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Temperature Autoignition of C8H16O2 Ethyl and Methyl Esters in a Motored Engine Low Temperature Autoignition of C8H16O2 Ethyl and Methyl Esters in a Motored Engine qThe alkyl chain ...

  16. Conversion of 1,3-Propylene Glycol on Rutile TiO2(110) (Journal...

    Office of Scientific and Technical Information (OSTI)

    Conversion of 1,3-Propylene Glycol on Rutile TiO2(110) Citation Details In-Document Search Title: Conversion of 1,3-Propylene Glycol on Rutile TiO2(110) The adsorption of...

  17. Compact Electrochemical Bi-functional NOx/O2 Sensors with an...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Compact Electrochemical Bi-functional NOxO2 Sensors with an Internal Reference for High Temperature Applications Compact Electrochemical Bi-functional NOxO2 Sensors with an...

  18. CO Oxidation mechanism on CeO2-supported Au nanoclusters

    SciTech Connect (OSTI)

    Kim H. Y.; Henkelman, G.

    2013-09-08

    To reveal the richer chemistry of CO oxidation by CeO2 supported Au Nanoclusters(NCs)/Nanoparticles, we design Au13 and Au12 supported on a flat and a stepped-CeO2 model (Au/CeO2) and study various kinds of CO oxidation mechanisms at the Au-CeO2 interface and the Au NC as well.

  19. Assessment of the O2Diesel Operational Safety Program: December 23, 2002 -- June 30, 2007

    SciTech Connect (OSTI)

    TIAX LLC

    2006-06-01

    This report assesses O2Diesel's operational safety program using its ethanol-diesel blended fuel product.

  20. Charging properties of cassiterite (alfa-SnO2) surfaces

    SciTech Connect (OSTI)

    Rosenqvist, Jorgen K; Machesky, Michael L.; Vlcek, L.; Cummings, Peter T; Wesolowski, David J

    2009-01-01

    The acid-base properties of cassiterite (alfa-SnO2) surfaces at 10 50 C were studied using potentiometric titrations of powder suspensions in aqueous NaCl and RbCl media. The proton sorption isotherms exhibited common intersection points in the pH-range 4.0 to 4.5 at all conditions and the magnitude of charging was similar but not identical in NaCl and RbCl. The hydrogen bonding configuration at the oxide-water interface, obtained from classical Molecular Dynamics (MD) simulations, was analyzed in detail and the results were explicitly incorporated in calculations of protonation constants for the reactive surface sites using the revised MUSIC model. The calculations indicated that the terminal SnOH2 group is more acidic than the bridging Sn2OH group, with protonation constants (log KH) of 3.60 and 5.13 at 25 C, respectively. This is contrary to the situation on the isostructural alfa-TiO2 (rutile), apparently due to the difference in electronegativity between Ti and Sn. MD simulations and speciation calculations indicated considerable differences in the speciation of Na+ and Rb+, despite the similarities in overall charging. Adsorbed sodium ions are almost exclusively found in bidentate surface complexes, while adsorbed rubidium ions form comparable amounts of bidentate and tetradentate complexes. Also, the distribution of adsorbed Na+ between the different complexes shows a considerable dependence on surface charge density (pH), while the distribution of adsorbed Rb+ is almost independent of pH. A Surface Complexation Model (SCM) capable of accurately describing both the measured surface charge and the MD predicted speciation of adsorbed Na+/Rb+ was formulated. According to the SCM, the deprotonated terminal group (SnOH-0.40) and the protonated bridging group (Sn2OH+0.36) dominate the surface speciation over the entire pH-range (2.7 10), illustrating the ability of positively and negatively charged surface groups to coexist. Complexation of the medium cations increases significantly with increasing negative surface charge and at pH 10 roughly 40 percent of the terminal sites are predicted to form cation complexes, while anion complexation is minor throughout the studied pH-range.

  1. iot | OpenEI Community

    Open Energy Info (EERE)

    - 13:42 How cleantech-as-a-service will drive renewable energy adoption 2015 adoption Big Data clean tech clean-tech cleantech cleantech forum cleantech-as-a-service cloud...

  2. Ethanol Steam Reforming on Co/CeO2: The Effect of ZnO Promoter

    SciTech Connect (OSTI)

    Davidson, Stephen; Sun, Junming; Wang, Yong

    2013-12-02

    A series of ZnO promoted Co/CeO2 catalysts were synthesized and characterized using XRD, TEM, H2-TPR, CO chemisorption, O2-TPO, IR-Py, and CO2-TPD. The effects of ZnO on the catalytic performances of Co/CeO2 were studied in ethanol steam reforming. It was found that the addition of ZnO facilitated the oxidation of Co0 via enhanced oxygen mobility of the CeO2 support which decreased the activity of Co/CeO2 in CC bond cleavage of ethanol. 3 wt% ZnO promoted Co/CeO2 exhibited minimum CO and CH4 selectivity and maximum CO2 selectivity. This resulted from the combined effects of the following factors with increasing ZnO loading: (1) enhanced oxygen mobility of CeO2 facilitated the oxidation of CHx and CO to form CO2; (2) increased ZnO coverage on CeO2 surface reduced the interaction between CHx/CO and Co/CeO2; and (3) suppressed CO adsorption on Co0 reduced CO oxidation rate to form CO2. In addition, the addition of ZnO also modified the surface acidity and basicity of CeO2, which consequently affected the C2C4 product distributions.

  3. Arrays of SiO(2) Substrate-Free Micromechanical Uncooled THz and Infrared

    Office of Scientific and Technical Information (OSTI)

    Detectors (Journal Article) | SciTech Connect Journal Article: Arrays of SiO(2) Substrate-Free Micromechanical Uncooled THz and Infrared Detectors Citation Details In-Document Search Title: Arrays of SiO(2) Substrate-Free Micromechanical Uncooled THz and Infrared Detectors We describe the design, fabrication, and characterization of arrays of uncooled infrared and terahertz micromechanical detectors that utilize SiO2 as a main structural material. Materials with highly dissimilar

  4. Compact Electrochemical Bi-functional NOx/O2 Sensors with an Internal

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Reference for High Temperature Applications | Department of Energy Compact Electrochemical Bi-functional NOx/O2 Sensors with an Internal Reference for High Temperature Applications Compact Electrochemical Bi-functional NOx/O2 Sensors with an Internal Reference for High Temperature Applications A inexpensive compact O2 sensor has been developed using internal reference gas that is stable for months, has no complex electronics, and is amenable to mass production PDF icon deer09_singh.pdf More

  5. Synthesis of Highly Ordered TiO2 Nanotubes Using Ionic Liquids for Photovoltaics Applications

    SciTech Connect (OSTI)

    2009-04-01

    This factsheet describes a study that deals with a new, green approach of synthesizing highly ordered TiO2 nanotubes using ionic liquids for photovoltaics (PV) applications.

  6. Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination...

    Office of Scientific and Technical Information (OSTI)

    Title: Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6 Authors: Kono, Yoshio ; Kenney-Benson, Curtis ; Ikuta, Daijo ; Shibazaki, Yuki ; Wang, Yanbin ; ...

  7. Photochromic MOFs for Control of 1O2 Generation | Center for Gas

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    SeparationsRelevant to Clean Energy Technologies | Blandine Jerome Photochromic MOFs for Control of 1O2 Generation Previous Next List

  8. Dimerization Induced Deprotonation of Water on RuO2(110)

    SciTech Connect (OSTI)

    Mu, Rentao; Cantu Cantu, David; Lin, Xiao; Glezakou, Vassiliki Alexandra; Wang, Zhitao; Lyubinetsky, Igor; Rousseau, Roger J.; Dohnalek, Zdenek

    2014-10-02

    RuO2 has proven to be indispensable as a co-catalyst in numerous systems designed for photocatalytic water splitting. In this study we have carried out a detailed mechanistic study of water behavior on the most stable RuO2 face, RuO2(110), by employing variable temperature scanning tunneling microscopy and density functional theory calculations. We show that water monomers adsorb molecularly on Ru sites, become mobile above 238 K, diffuse along the Ru rows and form water dimers. The onset for dimer diffusion is observed at ~277 K indicating significantly higher diffusion barrier than that for monomers. More importantly, we find that water dimers deprotonate readily to form Ru-bound H3O2 and bridging OH species. The observed behavior is compared and contrasted with that observed for water on isostructural rutile TiO2(110).

  9. Doping of TiO 2 Polymorphs for Altered Optical and Photocatalytic Properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nie, Xiliang; Zhuo, Shuping; Maeng, Gloria; Sohlberg, Karl

    2009-01-01

    Tmore » his paper reviews recent investigations of the influence of dopants on the optical properties of TiO 2 polymorphs. The common undoped polymorphs of TiO 2 are discussed and compared. The results of recent doping efforts are tabulated, and discussed in the context of doping by elements of the same chemical group. Dopant effects on the band gap and photocatalytic activity are interpreted with reference to a simple qualitative picture of the TiO 2 electronic structure, which is supported with first-principles calculations.« less

  10. Doping ofTiO2Polymorphs for Altered Optical and Photocatalytic Properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nie, Xiliang; Zhuo, Shuping; Maeng, Gloria; Sohlberg, Karl

    2009-01-01

    This paper reviews recent investigations of the influence of dopants on the optical properties ofTiO2polymorphs. The common undoped polymorphs ofTiO2are discussed and compared. The results of recent doping efforts are tabulated, and discussed in the context of doping by elements of the same chemical group. Dopant effects on the band gap and photocatalytic activity are interpreted with reference to a simple qualitative picture of theTiO2electronic structure, which is supported with first-principles calculations.

  11. Molecular Hydrogen Formation from Proximal Glycol Pairs on TiO2(110)

    SciTech Connect (OSTI)

    Chen, Long; Li, Zhenjun; Smith, R. Scott; Kay, Bruce D.; Dohnalek, Zdenek

    2014-04-16

    Understanding hydrogen formation on TiO2 surfaces is of great importance as it could provide fundamental insight into water splitting for hydrogen production using solar energy. In this work, hydrogen formation from glycols having different numbers of methyl end-groups have been studied using temperature pro-grammed desorption on reduced, hydroxylated, and oxidized TiO2(110) surfaces. The results from OD-labeled glycols demon-strate that gas-phase molecular hydrogen originates exclusively from glycol hydroxyl groups. The yield is controlled by a combi-nation of glycol coverage, steric hindrance, TiO2(110) order and the amount of subsurface charge. Combined, these results show that proximal pairs of hydroxyl aligned glycol molecules and subsurface charge are required to maximize the yield of this redox reaction. These findings highlight the importance of geometric and electronic effects in hydrogen formation from adsorbates on TiO2(110).

  12. In-situ Electrical Conductivity of LixMnO2 Nanowires as a Function...

    Office of Scientific and Technical Information (OSTI)

    of LixMnO2 Nanowires as a Function of "x" and Size Authors: Le, Mya ; Liu, Yu ; Wang, Hui ; Dutta, Rajen ; Yan, Wenbo ; Hemminger, John C ; Wu, Ruqian ; Penner, Reginald...

  13. The effect of f[subscript O2] on the partitioning and valence...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: The effect of fsubscript O2 on the partitioning and valence of V and Cr in garnetmelt pairs and the relation to terrestrial mantle V and Cr content Citation ...

  14. Nanocrystallization of LiCoO2 Cathodes for Thin Film Batteries Utilizing Pulse Thermal Processing

    SciTech Connect (OSTI)

    2009-04-01

    This factsheet describes a study whose focus is on the nanocrystallization of the LiCoO2 cathode thin films on polyimide substrates and evaluate the microstructural evolution and resistance as a function of PTP processing conditions.

  15. Ability of TiO2(110) Surface to Be Fully Hydroxylated and Fully...

    Office of Scientific and Technical Information (OSTI)

    The resulting hydroxylation can significantly alter its surface properties. While behavior of single, isolated OH species on the model metal oxide surface of rutile TiO2(110) is ...

  16. Palladium-tin catalysts for the direct synthesis of H2O2 with high selectivity

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Freakley, Simon J.; He, Qian; Harrhy, Jonathan H.; Lu, Li; Crole, David A.; Morgan, David J.; Ntainjua, Edwin N.; Edwards, Jennifer K.; Carley, Albert F.; Borisevich, Albina Y.; et al

    2016-02-25

    The direct synthesis of hydrogen peroxide (H2O2 ) from H2 and O2 represents a potentially atom-efficient alternative to the current industrial indirect process. We show that the addition of tin to palladium catalysts coupled with an appropriate heat treatment cycle switches off the sequential hydrogenation and decomposition reactions, enabling selectivities of >95% toward H2O2 . This effect arises from a tin oxide surface layer that encapsulates small Pd-rich particles while leaving larger Pd-Sn alloy particles exposed. In conclusion, we show that this effect is a general feature for oxide-supported Pd catalysts containing an appropriate second metal oxide component, and wemore » set out the design principles for producing high-selectivity Pd-based catalysts for direct H2O2 production that do not contain gold.« less

  17. Fuel and Fuel Additive Registration Testing of Ethanol-Diesel Blend for O2Diesel, Inc.

    SciTech Connect (OSTI)

    Fanick, E. R.

    2004-02-01

    O2 Diesel Inc. (formerly AAE Technologies Inc.) tested a heavy duty engine with O2Diesel (diesel fuel with 7.7% ethanol and additives) for regulated emissions and speciation of vapor-phase and semi-volatile hydrocarbon compounds. This testing was performed in support of EPA requirements for registering designated fuels and fuel additives as stipulated by sections 211(b) and 211(e) of the Clean Air Act.

  18. Polycrystalline TiO2(B) Nanosheet Films Deposited via Langmuir-Blodgett

    Office of Scientific and Technical Information (OSTI)

    Method. (Conference) | SciTech Connect Polycrystalline TiO2(B) Nanosheet Films Deposited via Langmuir-Blodgett Method. Citation Details In-Document Search Title: Polycrystalline TiO2(B) Nanosheet Films Deposited via Langmuir-Blodgett Method. Abstract not provided. Authors: Biedermann, Laura ; Kotula, Paul Gabriel ; Beechem Iii, Thomas Edwin ; Chan, Calvin ; Dylla, Anthony ; Stevenson, Keith Publication Date: 2014-03-01 OSTI Identifier: 1140906 Report Number(s): SAND2014-1720C 505110 DOE

  19. Mechanisms of Oriented Attachment of TiO2 Nanocrystals in Vacuum and Humid

    Office of Scientific and Technical Information (OSTI)

    Environments: Reactive Molecular Dynamics (Journal Article) | SciTech Connect Mechanisms of Oriented Attachment of TiO2 Nanocrystals in Vacuum and Humid Environments: Reactive Molecular Dynamics Citation Details In-Document Search Title: Mechanisms of Oriented Attachment of TiO2 Nanocrystals in Vacuum and Humid Environments: Reactive Molecular Dynamics Authors: Raju, Muralikrishna [1] ; Van Duin, Adri C. T. [2] ; Fichthorn, Kristen [1] + Show Author Affiliations Pennsylvania State

  20. Superconductivity in semimetallic B i 3 O 2 S 3 (Journal Article) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Superconductivity in semimetallic B i 3 O 2 S 3 Citation Details In-Document Search Title: Superconductivity in semimetallic B i 3 O 2 S 3 Authors: Li, L. ; Parker, D. ; Babkevich, P. ; Yang, L. ; Ronnow, H. M. ; Sefat, A. S. Publication Date: 2015-03-12 OSTI Identifier: 1180544 Type: Publisher's Accepted Manuscript Journal Name: Physical Review B Additional Journal Information: Journal Volume: 91; Journal Issue: 10; Journal ID: ISSN 1098-0121 Publisher: American Physical Society

  1. Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | DOE PAGES Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6 This content will become publicly available on September 14, 2016 Title: Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6 Authors: Kono, Yoshio ; Kenney-Benson, Curtis ; Ikuta, Daijo ; Shibazaki, Yuki ; Wang, Yanbin ; Shen, Guoyin Publication Date: 2016-03-14 OSTI Identifier: 1241555 Type: Published Article Journal Name: Proceedings of the National

  2. Composite WO3/TiO2 nanostructures for high electrochromic activity

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Reyes-Gil, Karla R.; Stephens, Zachary D.; Stavila, Vitalie; Robinson, David B.

    2015-01-06

    A composite material consisting of TiO2 nanotubes (NT) with WO3 electrodeposited on its surface has been fabricated, detached from its Ti substrate, and attached to a fluorine-doped tin oxide (FTO) film on glass for application to electrochromic (EC) reactions. Several adhesion layers were tested, finding that a paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length and WO3 concentration on the EC performancemore » were studied. As a result, the composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast, and longer memory time compared with the pure WO3 and TiO2 materials« less

  3. Composite WO3/TiO2 nanostructures for high electrochromic activity.

    SciTech Connect (OSTI)

    Reyes, Karla Rosa; Stephens, Zachary Dan.; Robinson, David B.

    2013-05-01

    A composite material consisting of TiO2 nanotubes (NTs) with WO3 electrodeposited homogeneously on its surface has been fabricated, detached from its substrate, and attached to a fluorine-doped tin oxide film on glass for application to electrochromic (EC) reactions. A paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length on the current density and the EC contrast of the material were studied. The EC redox reaction seen in this material is diffusion- limited, having relatively fast reaction rates at the electrode surface. The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast and longer memory time compared with the pure WO3 and TiO2.

  4. Location Of Hole And Electron Traps On Nanocrystalline Anatase TiO2

    SciTech Connect (OSTI)

    Mercado, Candy C.; Knorr, Fritz J.; McHale, Jeanne L.; Usmani, Shirin M.; Ichimura, Andrew S.; Saraf, Laxmikant V.

    2012-05-17

    The defect photoluminescence from TiO2 nanoparticles in the anatase phase is reported for nanosheets which expose predominantly (001) surfaces, and compared to that from conventional anatase nanoparticles which expose mostly (101) surfaces. Also reported is the weak defect photoluminescence of TiO2 nanotubes, which we find using electron back-scattered diffraction to consist of walls which expose (110) and (100) facets. The nanotubes exhibit photoluminescence that is blue-shifted and much weaker than that from conventional TiO2 nanoparticles. Despite the preponderance of (001) surfaces in the nanosheet samples, they exhibit photoluminescence similar to that of conventional nanoparticles. We assign the broad visible photoluminescence of anatase nanoparticles to two overlapping distributions: hole trap emission associated with oxygen vacancies on (101) exposed surfaces, which peaks in the green, and a broader emission extending into the red which results from electron traps on under-coordinated titanium atoms, which are prevalent on (001) facets. The results of this study suggest how morphology of TiO2 nanoparticles could be optimized to control the distribution and activity of surface traps. Our results also shed light on the mechanism by which the TiCl4 surface treatment heals traps on anatase and mixed-phase TiO2 films, and reveals distinct differences in the trap-state distributions of TiO2 nanoparticles and nanotubes. The molecular basis for electron and hole traps and their spatial separation on different facets is discussed.

  5. CO Oxidation at the Interface of Au Nanoclusters and the Stepped-CeO2(111) Surface

    SciTech Connect (OSTI)

    Kim H. Y.; Henkelman, G.

    2013-01-14

    To reveal the richer chemistry of CO oxidation by CeO2 supported Au Nanoclusters NCs)/Nanoparticles, we design a Au12 supported on a stepped-CeO2 model (Au/CeO2-step) and study various kinds of CO oxidation mechanisms at the interface of the Au/CeO2-step: oxygen spillover from the CeO2 to the Au NCs;2 CO oxidation by the O2 bound to the Au-Ce3+ interface;3 and CO oxidation by the Mars-van Krevelen (M-vK) mechanism.4 DFT+U calculations show that lattice oxygen at the CeO2 step edge oxidizes CO bound to Au NCs by the M-vK mechanism. CO2 desorption determines the rate of CO oxidation and the vacancy formation energy (Evac) is a reactivity descriptor for CO oxidation. The maximum Evac that insures spontaneous CO2 production is higher for the Au/CeO2-step than the Au/CeO2-surface suggesting that the CeO2-step is a better supporting material than the CeO2-surface for CO oxidation by the Au/CeO2. Our results also suggest that for CO oxidation by Au NCs supported on nano- or meso-structured CeO2, which is the case of industrial catalysts, the M-vK mechanism accounts for a large portion of the total activity.

  6. Effects of electrolyte salts on the performance of Li-O2 batteries

    SciTech Connect (OSTI)

    Nasybulin, Eduard N.; Xu, Wu; Engelhard, Mark H.; Nie, Zimin; Burton, Sarah D.; Cosimbescu, Lelia; Gross, Mark E.; Zhang, Jiguang

    2013-02-05

    It is well known that the stability of nonaqueous electrolyte is critical for the rechargeable Li-O2 batteries. Although stability of many solvents used in the electrolytes has been investigated, considerably less attention has been paid to the stability of electrolyte salt which is the second major component. Herein, we report the systematic investigation of the stability of seven common lithium salts in tetraglyme used as electrolytes for Li-O2 batteries. The discharge products of Li-O2 reaction were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy. The performance of Li-O2 batteries was strongly affected by the salt used in the electrolyte. Lithium tetrafluoroborate (LiBF4) and lithium bis(oxalato)borate (LiBOB) decompose and form LiF and lithium borates, respectively during the discharge of Li-O2 batteries. Several other salts, including lithium bis(trifluoromethane)sulfonamide (LiTFSI), lithium trifluoromethanesulfonate (LiTf), lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4) , and lithium bromide (LiBr) led to the discharge products which mainly consisted of Li2O2 and only minor signs of decomposition of LiTFSI, LiTf, LPF6 and LiClO4 were detected. LiBr showed the best stability during the discharge process. As for the cycling performance, LiTf and LiTFSI were the best among the studied salts. In addition to the instability of lithium salts, decomposition of tetraglyme solvent was a more significant factor contributing to the limited cycling stability. Thus a more stable nonaqueous electrolyte including organic solvent and lithium salt still need to be further developed to reach a fully reversible Li-O2 battery.

  7. Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipimore » tation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths ( > 400   nm ). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe 2 O 4 narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visible-light-activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites has been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.« less

  8. Redox probing study of the potential dependence of charge transport through Li2O2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Knudsen, Kristian B.; Luntz, Alan C.; Jensen, Søren H.; Vegge, Tejs; Hjelm, Johan

    2015-11-20

    In the field of energy storage devices the pursuit for cheap, high energy density, reliable secondary batteries is at the top of the agenda. The Li–O2 battery is one of the possible technologies that, in theory, should be able to close the gap, which exists between the present state-of-the-art Li-ion technologies and the demand placed on batteries by technologies such as electrical vehicles. Here we present a redox probing study of the charge transfer across the main deposition product lithium peroxide, Li2O2, in the Li–O2 battery using outer-sphere redox shuttles. The change in heterogeneous electron transfer exchange rate as amore » function of the potential and the Li2O2 layer thickness (~depth-of-discharge) was determined using electrochemical impedance spectroscopy. In addition, the attenuation of the electron transfer exchange rate with film thickness is dependent on the probing potential, providing evidence that hole transport is the dominant process for charge transfer through Li2O2 and showing that the origin of the sudden death observed upon discharge is due to charge transport limitations.« less

  9. WO3/TiO2 nanotube photoanodes for solar water splitting with simultaneous wastewater treatment.

    SciTech Connect (OSTI)

    Reyes, Karla Rosa; Robinson, David B.

    2013-05-01

    Nanostructured WO3/TiO2 nanotubes with properties that enhance solar photoconversion reactions were developed, characterized and tested. The TiO2 nanotubes were prepared by anodization of Ti foil, and WO3 was electrodeposited on top of the nanotubes. SEM images show that these materials have the same ordered structure as TiO2 nanotubes, with an external nanostructured WO3 layer. Diffuse reflectance spectra showed an increase in the visible absorption relative to bare TiO2 nanotubes, and in the UV absorption relative to bare WO3 films. Incident simulated solar photon-to-current efficiency increased from 30% (for bare WO3) to 50% (for WO3/TiO2 composites). With the addition of diverse organic pollutants, the photocurrent densities exhibited more than a 5-fold increase. Chemical oxygen demand measurements showed the simultaneous photodegradation of organic pollutants. The results of this work indicate that the unique structure and composition of these composite materials enhance the charge carrier transport and optical properties compared with the parent materials.

  10. Synthesis and Characterization of PhotocatalyticTiO2-ZnFe2O4Nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipitation/hydrolysis synthesis route is used to create aTiO2-ZnFe2O4nanocomposite that is directed towards extending the photoresponse ofTiO2from UV to visible wavelengths (>400?nm). The effect ofTiO2's accelerated anatase-rutile phase transformation due to the presence of the coupledZnFe2O4narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, andZnFe2O4concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in aZnFe2O4nanocomposite are outlined. The visible-light-activated photocatalytic activity of theTiO2-ZnFe2O4nanocomposites has been compared to an AldrichTiO2reference catalyst, using a solar-simulated photoreactor formorethe degradation of phenol.less

  11. Dendrimer-Encapsulated Ruthenium Nanoparticles as Catalysts for Lithium-O2 Batteries

    SciTech Connect (OSTI)

    Bhattacharya, Priyanka; Nasybulin, Eduard N.; Engelhard, Mark H.; Kovarik, Libor; Bowden, Mark E.; Li, Shari; Gaspar, Daniel J.; Xu, Wu; Zhang, Jiguang

    2014-12-01

    Dendrimer-encapsulated ruthenium nanoparticles (DEN-Ru) have been used as catalysts in lithium-O2 batteries for the first time. Results obtained from UV-vis spectroscopy, electron microscopy and X-ray photoelectron spectroscopy show that the nanoparticles synthesized by the dendrimer template method are ruthenium oxide instead of metallic ruthenium reported earlier by other groups. The DEN-Ru significantly improve the cycling stability of lithium (Li)-O2 batteries with carbon black electrodes and decrease the charging potential even at low catalyst loading. The monodispersity, porosity and large number of surface functionalities of the dendrimer template prevent the aggregation of the ruthenium nanoparticles making their entire surface area available for catalysis. The potential of using DEN-Ru as stand-alone cathode materials for Li-O2 batteries is also explored.

  12. Visible Light Photocatalysis via CdS/TiO2Nanocomposite Materials

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    Nanostructured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers, and selective reduction/oxidation of different classes of organic compounds. In the present paper, we have carried out a systematic synthesis of nanostructured CdS-TiO2via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS-TiO2nanocomposites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water suspension.

  13. Low Temperature Autoignition of C8H16O2 Ethyl and Methyl Esters in a

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Motored Engine | Department of Energy Temperature Autoignition of C8H16O2 Ethyl and Methyl Esters in a Motored Engine Low Temperature Autoignition of C8H16O2 Ethyl and Methyl Esters in a Motored Engine qThe alkyl chain of fatty acid esters experience the typical paraffin-like low temperature oxidation sequence; the alkyl chain length of fatty acid esters has a crucial impact on the ignition behavior of fatty acid esters PDF icon deer09_boehman.pdf More Documents & Publications Low

  14. Development of a Thermal Transport Database for Air Plasma Sprayed ZrO2 ?

    Office of Scientific and Technical Information (OSTI)

    Y2O3 Thermal Barrier Coatings (Journal Article) | SciTech Connect Journal Article: Development of a Thermal Transport Database for Air Plasma Sprayed ZrO2 ? Y2O3 Thermal Barrier Coatings Citation Details In-Document Search Title: Development of a Thermal Transport Database for Air Plasma Sprayed ZrO2 ? Y2O3 Thermal Barrier Coatings Thermal Diffusivities of Air Plasma Sprayed (APS) thermal barrier coatings (TBCs) are measured by the laser flash method. The data are used to calculate thermal

  15. Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6 Citation Details In-Document Search This content will become publicly available on September 14, 2016 Title: Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6 Authors: Kono, Yoshio ; Kenney-Benson, Curtis ; Ikuta, Daijo ; Shibazaki, Yuki ; Wang, Yanbin ; Shen, Guoyin Publication Date: 2016-03-14 OSTI

  16. Transparent TiO2 nanotube array photoelectrodes prepared via two-step anodization

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, Jin Young; Zhu, Kai; Neale, Nathan R.; Frank, Arthur J.

    2014-04-04

    Two-step anodization of transparent TiO2 nanotube arrays has been demonstrated with aid of a Nb-doped TiO2 buffer layer deposited between the Ti layer and TCO substrate. Enhanced physical adhesion and electrochemical stability provided by the buffer layer has been found to be important for successful implementation of the two-step anodization process. As a result, with the proposed approach, the morphology and thickness of NT arrays could be controlled very precisely, which in turn, influenced their optical and photoelectrochemical properties.

  17. NOx/O2 Sensors for High-Temperature Applications | Argonne National

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laboratory NOx/O2 Sensors for High-Temperature Applications Technology available for licensing: Low-cost bifunctional high-temperature NOx/oxygen sensor that provides real-time sensing inside a combustion chamber without the requirement of a reference air supply. Placement in combustion chamber provide accurate oxygen-sensing, extremely low drift 2-10% energy saving from sensor optimization of air-flow ratio and fuel oil viscosity PDF icon high-temp_NOx-O2_sensor

  18. Invoking any Intel compiler with a Cray wrapper with -g defaults to -O2

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    optimization contrary to the Intel compiler man pages Invoking any Intel compiler with a Cray wrapper with -g defaults to -O2 optimization contrary to the Intel compiler man pages Invoking any Intel compiler with a Cray wrapper with -g defaults to -O2 optimization contrary to the Intel compiler man pages January 30, 2014 Status: Filed bug 776949 with Cray but they regard it as an Intel feature. The Intel compiler man pages ifort, icc, and icpc all state that the -g optimization causes the

  19. Metal-Organic Frameworks for the Separation of O2 from Air - Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Innovation Portal Industrial Technologies Industrial Technologies Find More Like This Return to Search Metal-Organic Frameworks for the Separation of O2 from Air Sandia National Laboratories Contact SNL About This Technology Publications: PDF Document Publication Market Sheet (340 KB) <br type="_moz" /> Mesoporous cages in MOF for O<sub>2</sub><br type="_moz" /> Mesoporous cages in MOF for O2 Technology Marketing Summary Pure molecular oxygen is

  20. Structural Environment of Nitrogen in N-doped Rutile TiO2(110)

    SciTech Connect (OSTI)

    Henderson, Michael A.; Shutthanandan, V.; Ohsawa, Takeo; Chambers, Scott A.

    2010-12-31

    We employ x-ray photoelectron spectroscopy (XPS), reflection high-energy electron diffraction (RHEED) and nuclear reaction analysis (NRA) to characterize the concentration-dependent structural properties of nitrogen doping into rutile TiO2. High quality N-doped TiO2 were prepared on rutile single crystal TiO2(110) substrates using plasma-assisted molecular beam epitaxy with an electron cyclotron resonance (ECR) plasma and Ti effusive sources. Films with N dopant concentrations at or below 2 at.% exhibited predominately substitutional doping based on NRA data, whereas films with concentrations above this limit resulted in little or no substitutional N and surfaces rich in Ti3+. The binding energy of the N 1s feature in XPS did not readily distinguish between these two extremes in N-doping, rendering features within 0.4 eV of each other and similar peak profiles. Although widely used to characterize the state of N in anion-doped TiO2 materials, we find that XPS is unsuitable for this task.

  1. Ionic liquid-assisted sonochemical preparation of CeO2 nanoparticles for CO oxidation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Alammar, Tarek; Noei, Heshmat; Wang, Yuemin; Grünert, Wolfgang; Mudring, Anja -Verena

    2014-10-10

    CeO2 nanoparticles were synthesized via a one-step ultrasound synthesis in different kinds of ionic liquids based on bis(trifluoromethanesulfonylamide, [Tf2N]–, in combination with various cations including 1-butyl-3-methylimidazolium ([C4mim]+), 1-ethyl-2,3-dimethylimidazolium ([Edimim]+), butyl-pyridinium([Py4]+), 1-butyl-1-methyl-pyrrolidinium ([Pyrr14]+), and 2-hydroxyethyl-trimethylammonium ([N1112OH]+). Depending on synthetic parameters, such as ionic liquid, Ce(IV) precursor, heating method, and precipitator, formed ceria exhibits different morphologies, varying from nanospheres, nanorods, nanoribbons, and nanoflowers. The morphology, crystallinity, and chemical composition of the obtained materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and N2 adsorption. The structural and electronic propertiesmore » of the as-prepared CeO2 samples were probed by CO adsorption using IR spectroscopy under ultrahigh vacuum conditions. The catalytic activities of CeO2 nanoparticles were investigated in the oxidation of CO. CeO2 nanospheres obtained sonochemically in [C4mim][Tf2N] exhibit the best performance for low-temperature CO oxidation. As a result, the superior catalytic performance of this material can be related to its mesoporous structure, small particle size, large surface area, and high number of surface oxygen vacancy sites.« less

  2. Direct Evidence of Lithium-Induced Atomic Ordering in Amorphous TiO2 Nanotubes

    SciTech Connect (OSTI)

    Gao, Qi; Gu, Meng; Nie, Anmin; Mashayek, Farzad; Wang, Chong M.; Odegard, Gregory M.; Shahbazian-Yassar, Reza

    2014-01-27

    In this paper, we report the first direct chemical and imaging evidence of lithium-induced atomic ordering in amorphous TiO2 nanomaterials and propose new reaction mechanisms that contradict the many works in the published literature on the lithiation behavior of these materials. The lithiation process was conducted in situ inside an atomic resolution transmission electron microscope. Our results indicate that the lithiation started with the valence reduction of Ti4+ to Ti3+ leading to a LixTiO2 intercalation compound. The continued intercalation of Li ions in TiO2 nanotubes triggered an amorphous to crystalline phase transformation. The crystals were formed as nano-islands and identified to be Li2Ti2O4 with cubic structure (a = 8.375 ). The tendency for the formation of these crystals was verified with density functional theory (DFT) simulations. The size of the crystalline islands provides a characteristic length scale (?5 nm) at which the atomic bonding configuration has been changed within a short time period. This phase transformation is associated with local inhomogeneities in Li distribution. On the basis of these observations, a new reaction mechanism is proposed to explain the first cycle lithiation behavior in amorphous TiO2 nanotubes.

  3. Preparation of atomically flat rutile TiO2(001) surfaces for oxide film growth

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Yang; Lee, Shinbuhm; Vilmercati, P.; Lee, Ho Nyung; Weitering, Hanno; Snijders, Paul C.

    2016-03-01

    The availability of low-index rutile TiO2 single crystal substrates with atomically flat surfaces is essential for enabling epitaxialgrowth of rutile transition metal oxide films. The high surface energy of the rutile (001) surface often leads to surface faceting, which precludes the sputter and annealing treatment commonly used for the preparation of clean and atomically flat TiO2(110) substrate surfaces. In this work, we reveal that stable and atomically flat rutile TiO2(001) surfaces can be prepared with an atomically ordered reconstructedsurface already during a furnace annealing treatment in air. We tentatively ascribe this result to the decrease in surface energy associated withmore » the surface reconstruction, which removes the driving force for faceting. Despite the narrow temperature window where this morphology can initially be formed, we demonstrate that it persists in homoepitaxialgrowth of TiO2(001) thin films. The stabilization of surface reconstructions that prevent faceting of high-surface-energy crystal faces may offer a promising avenue towards the realization of a wider range of high quality epitaxial transition metal oxide heterostructures.« less

  4. The Synthesis of Ag-Doped Mesoporous TiO2

    SciTech Connect (OSTI)

    Li, Xiaohong S.; Fryxell, Glen E.; Wang, Chong M.; Engelhard, Mark H.

    2008-04-15

    Ag-doped mesoporous titanium oxide was prepared using non-ionic surfactants and easily handled titanium precursors, under mild reaction conditions. In contrast to the stabilizing effect of Cd-doping on mesoporous TiO2, Ag-doping was found to significantly destabilize the mesoporous structure.

  5. Generation of Organic Radicals During Photocatalytic Reactions on TiO2

    SciTech Connect (OSTI)

    Henderson, Michael A.; Deskins, N. Aaron; Zehr, Robert T.; Dupuis, Michel

    2011-04-01

    Using a variety of organic carbonyl molecules (R1C(O)R2) and the rutile TiO2(110) surface as a model photocatalyst, we demonstrate both experimentally and theoretically that ejection of organic radicals from TiO2 surfaces is likely a prevalent reaction process occurring during heterogeneous photooxidationof organic molecules. Organic carbonyls react with coadsorbed oxygen species to form organic diolates which are more strongly bound to TiO2 than are the parent carbonyls. The parent carbonyls, when bound to TiO2(110) in an ?1 configuration, are photo-inactive. However, the diolates are shown to photodecompose by ejection one of the two R substituents from the surface into the gas phase, leaving behind the carboxylate of the other R group. Theoretical calculations using DFT show that in most cases the choice of which R group is ejected can be predicted based on the C-R bond energies and, to a lesser extent, the stability of the ejected R group.

  6. updated_supplemental_lists_1o_2o_3n_091812.xlsx | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    o_2o_3n_091812.xlsx More Documents & Publications updated_supplemental_lists_1n-2n-3m_07-06-2012.xlsx updated_supplemental_lists_1m-2m-3l-04-05-2012.xlsx updated_supplemental_lists_1p_2p_3o_04302013

  7. Investigation of the Rechargeability of Li-O2 Batteries in Non-aqueous Electrolyte

    SciTech Connect (OSTI)

    Xiao, Jie; Hu, Jian Z.; Wang, Deyu; Hu, Dehong; Xu, Wu; Graff, Gordon L.; Nie, Zimin; Liu, Jun; Zhang, Jiguang

    2011-07-01

    In order to understand the nature of the limited cycle life and poor energy efficiency associated with the secondary Li-O2 batteries the discharge products of primary Li-O2 cells at different depth of discharge (DOD) are systematically analyzed in this work. It is revealed that if discharged to 2.0 V a small amount of Li2O2 coexist with Li2CO3 and RO-(C=O)-OLi) in alkyl carbonate-based electrolyte. Further discharging the air electrodes to below 2.0 V the amount of Li2CO3 and LiRCO3 increases significantly due to the severe electrolyte decomposition. There is no Li2O detected in this alkyl carbonate electrolyte regardless of DOD. It is also found that the alkyl carbonate based electrolyte begins to decompose at 4.0 V during charging under the combined influences from the high surface area carbon, the nickel metal current collector and the oxygen atmosphere. Accordingly the impedance of the Li-O2 cell continues to increase after each discharge and recharge process indicating a repeated plating of insoluble lithium salts on the carbon surface. Therefore the whole carbon electrode becomes completely insulated only after a few cycles and loses the function of providing active tri-phase regions for the Li-oxygen batteries.

  8. Enhancing low-temperature activity and durability of Pd-based diesel oxidation catalysts using ZrO2 supports

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, Mi -Young; Kyriakidou, Eleni A.; Choi, Jae -Soon; Toops, Todd J.; Binder, Andrew J.; Thomas, Cyril; Schwartz, Viviane; Chen, Jihua; Hensley, Dale K.; Parks, II, James E.

    2016-01-18

    In this study, we investigated the impact of ZrO2 on the performance of palladium-based oxidation catalysts with respect to low-temperature activity, hydrothermal stability, and sulfur tolerance. Pd supported on ZrO2 and SiO2 were synthesized for a comparative study. Additionally, in an attempt to maximize the ZrO2 surface area and improve sulfur tolerance, a Pd support with ZrO2-dispersed onto SiO2 was studied. The physicochemical properties of the catalysts were examined using ICP, N2 sorption, XRD, SEM, TEM, and NH3-, CO2-, and NOx-TPD. The activity of the Pd catalysts were measured from 60 to 600 °C in a flow of 4000 ppmmore » CO, 500 ppm NO, 1000 ppm C3H6, 4% O2, 5% H2O, and Ar balance. The Pd catalysts were evaluated in fresh, sulfated, and hydrothermally aged states. Overall, the ZrO2-containing catalysts showed considerably higher CO and C3H6 oxidation activity than Pd/SiO2 under the reaction conditions studied.« less

  9. Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on (001)

    Office of Scientific and Technical Information (OSTI)

    ceria (Journal Article) | SciTech Connect Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on (001) ceria Citation Details In-Document Search Title: Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on (001) ceria Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process.

  10. Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells

    SciTech Connect (OSTI)

    Nie, Zimin; Zhou, Xiaoyuan; Zhang, Qifeng; Cao, Guozhong; Liu, Jun

    2013-11-01

    One-dimensional (1D) semiconducting oxides have attracted great attention for dye sensitized solar cells (DSCs), but the overall performance is still quite limited as compared to TiO2 nanocrystalline DSCs. Here, we report the synthesis of aggregated TiO2 based nanotubes with controlled morphologies and crystalline structures to obtain an overall power conversion efficiency of 9.9% using conventional dye without any additional chemical treatment steps. The high efficiency is attributed to the unique aggregate structure for light harvesting, optimized high surface area, and good crystallinity of the nanotube aggregates obtained through proper thermal annealing. This study demonstrates that high efficiency DSCs can be obtained with 1D nanomaterials, and provides lessons on the importance of optimizing both the nanocrystalline structure and the overall microscale morphology.

  11. Visible Light Photocatalysis via CdS/ TiO 2 Nanocomposite Materials

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    Nmore » anostructured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers, and selective reduction/oxidation of different classes of organic compounds. In the present paper, we have carried out a systematic synthesis of nanostructured CdS- TiO 2 via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS- TiO 2 nanocomposites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water suspension.« less

  12. XAFS Study on TiO2 Photocatalyst Loaded on Zeolite Synthesized from Steel Slag

    SciTech Connect (OSTI)

    Kuwahara, Yasutaka; Ohmichi, Tetsutaro; Mori, Kosuke; Katayama, Iwao; Yamashita, Hiromi

    2007-02-02

    The convenient route for the synthesis of Y-zeolites by utilizing steel slag as a material source was developed. Through hydrothermal treatment, well-crystallized Y-zeolite was obtained. We also synthesized TiO2-loaded Y-zeolites by an impregnation method. The structure of titanium oxide species highly dispersed on the zeolite, which couldn't be detected by XRD patterns, was investigated by XAFS analysis. Photocatalytic activity for decomposition of 2-propanol in liquid phase was found to be enhanced by the hydrophobic surface property of zeolite. It has been demonstrated that the zeolite synthesized from steel slag would be applicable as a promising support of TiO2 photocatalyst.

  13. Reactivity and reaction intermediates for acetic acid adsorbed on CeO2(111)

    SciTech Connect (OSTI)

    Calaza, Florencia; Chen, Tsung-Liang; Mullins, David R; Xu, Ye; Overbury, Steven {Steve} H

    2015-01-01

    Adsorption and reaction of acetic acid on a CeO2(1 1 1) surface was studied by a combination of ultra-highvacuum based methods including temperature desorption spectroscopy (TPD), soft X-ray photoelectronspectroscopy (sXPS), near edge X-ray absorption spectroscopy (NEXAFS) and reflection absorption IRspectroscopy (RAIRS), together with density functional theory (DFT) calculations. TPD shows that thedesorption products are strongly dependent upon the initial oxidation state of the CeO2surface, includingselectivity between acetone and acetaldehyde products. The combination of sXPS and NEXAFS demon-strate that acetate forms upon adsorption at low temperature and is stable to above 500 K, above whichpoint ketene, acetone and acetic acid desorb. DFT and RAIRS show that below 500 K, bridge bondedacetate coexists with a moiety formed by adsorption of an acetate at an oxygen vacancy, formed bywater desorption.

  14. Mechanical and electrochemical response of a LiCoO2 cathode using reconstructed microstructures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mendoza, Hector; Roberts, Scott Alan; Brunini, Victor E.; Grillet, Anne M.

    2016-01-02

    As LiCoO2 cathodes are charged, delithiation of the LiCoO2 active material leads to an increase in the lattice spacing, causing swelling of the particles. When these particles are packed into a bicontinuous, percolated network, as is the case in a battery electrode, this swelling leads to the generation of significant mechanical stress. In this study we performed coupled electrochemical-mechanical simulations of the charging of a LiCoO2 cathode in order to elucidate the mechanisms of stress generation and the effect of charge rate and microstructure on these stresses. Energy dispersive spectroscopy combined with scanning electron microscopy imaging was used to createmore » 3D reconstructions of a LiCoO2 cathode, and the Conformal Decomposition Finite Element Method is used to automatically generate computational meshes on this reconstructed microstructure. Replacement of the ideal solution Fickian diffusion model, typically used in battery simulations, with a more general non-ideal solution model shows substantially smaller gradients of lithium within particles than is typically observed in the literature. Using this more general model, lithium gradients only appear at states of charge where the open-circuit voltage is relatively constant. While lithium gradients do affect the mechanical stress state in the particles, the maximum stresses are always found in the fully-charged state and are strongly affected by the local details of the microstructure and particle-to-particle contacts. These coupled electrochemical-mechanical simulations begin to yield insight into the partitioning of volume change between reducing pore space and macroscopically swelling the electrode. Lastly, preliminary studies that include the presence of the polymeric binder suggest that it can greatly impact stress generation and that it is an important area for future research.« less

  15. Electron-Stimulated Reactions and O-2 Production in Methanol-Covered Amorphous Solid Water Films

    SciTech Connect (OSTI)

    Akin, Minta C.; Petrik, Nikolay G.; Kimmel, Gregory A.

    2009-03-14

    The low-energy, electron-stimulated desorption (ESD) of molecular products from amorphous solid water (ASW) films capped with methanol is investigated versus methanol coverage (0 - 4 x 1015 cm-2) at 50 K using 100 eV incident electrons. The major ESD products from a monolayer of methanol on ASW are quite similar to the ESD products from bulk methanol film: H2, CH4, H2O, C2H6, CO, CH2O, and CH3OH. For 40 ML ASW films, the molecular oxygen, hydrogen, and water ESD yields from the ASW are suppressed with increasing methanol coverage, while the CH3OH ESD yield increases proportionally to the methanol coverage. The suppression of the water ESD products by methanol is consistent with the non-thermal reactions occurring preferentially at or near the ASW/vacuum interface and not in the interior of the film. The water and molecular hydrogen ESD yields from the water layer decrease exponentially with the methanol cap coverage with 1/e constants of ~ 0.6 x 1015 cm-2 and 1.6 x 1015 cm-2, respectively. In contrast, the O2 ESD from the water layer is very efficiently quenched by small amounts of methanol (1/e ~ 6.5 x 1013 cm-2). The rapid suppression of O2 production by small amounts of methanol is due to reactions between CH3OH and the precursors for the O2 - mainly OH radicals. A kinetic model for the O2 ESD which semi-quantitatively accounts for the observations is presented.

  16. Compact Combination NOx/O2 Sensors for High-Temperature Applications -

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy Innovation Portal Find More Like This Return to Search Compact Combination NOx/O2 Sensors for High-Temperature Applications Argonne National Laboratory Contact ANL About This Technology <p> <em>High-temperature potentiometric oxygen sensor with internal reference. The deformation bonding method produces pore-free, gas-tight joints between ceramic shell components while retaining material strength and ion conductivity.</em></p> High-temperature potentiometric

  17. NREL: Photovoltaics Research - NREL Reveals Benefits of O2 Contact with

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Defects in 2D Semiconductors Reveals Benefits of O2 Contact with Defects in 2D Semiconductors December 11, 2015 Researchers at the Energy Department's National Renewable Energy Laboratory (NREL) have explained the unusual behavior that stems from oxygen molecules interacting with defects in two-dimensional (2D) semiconductors. Yuanyue Liu, Pauls Stradins, and Su-Huai Wei have published their findings, "Air Passivation of Chalcogen Vacancies in Two-Dimensional Semiconductors," in

  18. Valence electronenergy-lossspectroscopystudyofZrSiO4 and ZrO2

    SciTech Connect (OSTI)

    Spence, John; Jiang, Nan

    2013-07-01

    ZrSiO4 (zircon) and m-ZrO2 (zirconia) are fundamental and industrially important materials.This work reports the detailed valence electron energy-loss spectroscopy (VEELS) studies of these compounds. The dielectric response functions, as well as single-electron interband transition spectra,are derived from VEELS data for both ZrSiO4 and m-ZrO2, in the rang e550 eV using the KramersKronig analysis method. Our interpretation of the interband transitions is given with the aid of ab initio calculations of density of states. The bandgap energies for both materials are also measured using VEELS.The surface and bulk plasmons are identified: the surface plasmon peaks locate at around 12 eV,and two bulk plasmon peaks are ~1516 eV and ~2527 eV,respectively.Although similarities in the VEELS exist between ZrSiO4 and m-ZrO2, two majo rdifferences are als onoticed and explained in terms of composition and structure differences.

  19. Atomistic Studies of Cation Transport in Tetragonal ZrO2 During Zirconium Corrosion

    SciTech Connect (OSTI)

    Xian-Ming Bai; Yongfeng Zhang; Michael R. Tonks

    2013-10-01

    Zirconium alloys are the major fuel cladding materials in current reactors. The water-side corrosion is one of the major degradation mechanisms of these alloys. During corrosion the transport of oxidizing species in zirconium dioxide (ZrO2) determines the corrosion kinetics. Previously it has been argued that the outward diffusion of cation ions is important for forming protective oxides. In this work, the migration of Zr defects in tetragonal ZrO2 is studied with temperature accelerated dynamics and molecular dynamics simulations. The results show that Zr interstitials have anisotropic diffusion and migrate preferentially along the [001] or c direction in tetragonal ZrO2. The compressive stresses can increase the Zr interstitial migration barrier significantly. The migration barriers of some defect clusters can be much lower than those of point defects. The migration of Zr interstitials at some special grain boundaries is much slower than in a bulk oxide. The implications of these atomistic simulation results in the Zr corrosion are discussed.

  20. Probing the photochemistry of chemisorbed oxygen on TiO2(110) with Kr and other co-adsorbates

    SciTech Connect (OSTI)

    Petrik, Nikolay G.; Kimmel, Gregory A.

    2014-02-14

    Weakly bound (physisorbed) atoms and molecules such as Ar, Kr, Xe, CO, CH4, CH3OH, CO2 and N2 are used to probe the photochemical interactions of O2 on rutile TiO2(110). UV irradiation of chemisorbed O2 along with the physisorbed probe species leads to photon-stimulated desorption (PSD) of Ar, Kr, CO, CH4 and N2. Without co-adsorbed O2, the PSD yields of the probe species are very low or not observed. No PSD was observed for CO2, N2O, CH3OH and the PSD yield for Xe is very low compared to the other probe atoms or molecules. The angular distribution of the photo-desorbing Kr, which is broad and cosine, is quite different from the O2 PSD angular distribution, which is sharply peaked along the surface normal. The Kr PSD yields increase with increasing coverage of Kr and of chemisorbed O2. We propose a mechanism for the observed phenomena where the chemisorbed O2 serves as photoactive center, excited via electronic excitations (electrons and/or holes) created in the TiO2 substrate by UV photon irradiation. The photo-excited O2 may transfer its energy to neighboring co-adsorbed atom or molecule resulting in desorption of the latter. Simple momentum transfer considerations suggest that heavier adsorbates (like Xe) and adsorbates with higher binding energy (like CO2) should desorb less efficiently according to the proposed mechanism. Various forms of chemisorbed O2 appeared photoactive in such stimulated desorption of Kr atoms: molecular anions (O22-, O2-), adatoms (Oa), and others. The observed phenomenon provides a new tool for study of photocatalysis.

  1. Standards for the wireless IoT

    Energy Savers [EERE]

    8% ZigBee Light Link 17% ZigBee Telecom Services 1% Green Power 1% ZigBee Health Care 1% ZigBee Gateway 1% ZigBee Building Automation 1% ZigBee Retail Services 0% ZigBee...

  2. Semantic Historian for IoT Applications

    Broader source: Energy.gov (indexed) [DOE]

    and maintained by SmartCloud - Applications hosted either at customer premise, in cloud, or at secured data center * Investment from Rockwell Automation in 2013 3 > Customers...

  3. Role of Water in Methanol Photochemistry on Rutile TiO2(110)

    SciTech Connect (OSTI)

    Shen, Mingmin; Henderson, Michael A.

    2012-08-07

    Photochemistry of the molecularly and dissociatively adsorbed forms of methanol on the vacuum-annealed rutile TiO2(110) surface was explored using temperature programmed desorption (TPD), both with and without coadsorbed water. Methoxy, and not methanol, was confirmed as the photochemically active form of adsorbed methanol on this surface. UV irradiation of methoxy-covered TiO2(110) lead to depletion of the methoxy coverage and formation of formaldehyde and a surface OH group. Coadsorbed water did not promote either molecular methanol photochemistry or thermal decomposition of methanol to methoxy. However, terminal OH groups (OHt), prepared by coadsorption of water and oxygen atoms, thermally converted molecularly adsorbed methanol to methoxy at 120 K, thus enabling photoactivity. While chemisorbed water molecules had no influence on methoxy photochemistry, water molecules hydrogen-bonded in the second layer to bridging oxygen (Obr) sites inhibited the methoxy photodecomposition to formaldehyde. From this we conclude that Obr sites accept protons from the hole-mediated conversion of methoxy to formaldehyde. These results provide new fundamental understanding of the hole-scavenging role of methanol in photochemical processes on TiO2-based materials and how water influences this photochemistry. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle under contract DEAC05-76RL01830. The research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  4. Importance of Diffusion in Methanol Photochemistry on TiO2(110)

    SciTech Connect (OSTI)

    Shen, Mingmin; Acharya, Danda P.; Dohnalek, Zdenek; Henderson, Michael A.

    2012-12-06

    The photoactivity of methanol on the rutile TiO2(110) surface is shown to depend on the ability of methanol to diffuse on the surface and find sites active for its thermal dissociation to methoxy. Temperature programmed desorption (TPD) results show that the extent of methanol photodecomposition to formaldehyde is negligible on the clean TiO2(110) surface at 100 K due to a scarcity of sites that can convert (photoinactive) methanol to (photoactive) methoxy. The extent of photoactivity at 100 K significantly increases when methanol is coadsorbed with oxygen, however only those molecules able to adsorb near (next to) a coadsorbed oxygen species are active. Preannealing coadsorbed methanol and oxygen to above 200 K prior to UV irradiation results in a significant increase in photoactivity. Scanning tunneling microscopy (STM) images clearly show that the advent of increased photoactivity in TPD correlates with the onset of methanol diffusion along the surfaces Ti4+ rows at ~200 K. These results demonstrate that optimizing thermal processes (such as diffusion or proton transfer reactions) can be critical to maximizing photocatalytic reactivity on TiO2 surfaces. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle under contract DEAC05-76RL01830. The research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  5. Oxidative Dissolution Potential of Biogenic and Abiogenic TcO2 in Subsurface Sediments

    SciTech Connect (OSTI)

    Fredrickson, Jim K.; Zachara, John M.; Plymale, Andrew E.; Heald, Steve M.; McKinley, James P.; Kennedy, David W.; Liu, Chongxuan; Nachimuthu, Ponnusamy

    2009-04-15

    Technetium-99 (Tc) is an important fission product contaminant associated with sites of nuclear fuels reprocessing and geologic nuclear waste disposal. Exhibiting an intermediate redox potential, Tc is highly mobile in its anionic, oxidized state [Tc(VII)O4-]; and less mobile as a poorly soluble oxyhydroxide precipitate [Tc(IV)O2•nH2O] in its reduced state. Here we investigate the potential for oxidation of Tc(IV) that was heterogeneously reduced by reaction with biogenic Fe(II) in two sediments differing in mineralogy and aggregation state (FRC, RG). Both sediments contained Fe(III) and Mn(III/IV) as redox active phases, but FRC also contained mass-dominant Fe-phyllosilicates of different types. Biogenic Tc(IV)O2•nH2O was oxidized in anoxic, but unreduced RG and FRC sediments through redox interaction with Mn(III/IV) oxides. Bioreduction by Shewanella putrefaciens CN32 dissolved Mn(III/IV) oxides and generated biogenic Fe(II) that was reactive with Tc(VII) in heat-killed, bioreduced sediment. Biogenic Fe(II) in the FRC exceeded that in RG by a factor of two. More rapid reduction rates were observed in the RG that had lower biogenic Fe(II), and less particle aggregation. EXAFS measurements indicated that the primary reduction product was a TcO2-like phase in both sediments. Redox product Tc(IV) oxidized rapidly and completely in RG when contacted with air. Oxidation, in contrast, was slow and incomplete in the FRC, in spite of similar molecular speciation to RG. X-ray microprobe, electron microprobe, x-ray absorption spectroscopy, and micro x-ray diffraction were applied to the whole sediment and isolated Tc-contained particles. These analyses revealed that non-oxidizable Tc(IV) in the FRC existed as complexes with octahedral Fe(III) within intra-grain domains of 50-100 µm-sized, Fe-containing micas presumptively identified as celadonite. The markedly slower oxidation rates in FRC as compared to RG were attributed to mass-transfer-limited migration of O2 into intra-aggregate and intraparticle domains where Tc(IV) existed; and the formation of unique, oxidation-resistant, intragrain Tc(IV)-Fe(III) molecular species.

  6. Enhanced O2 selectivity versus N2 by partial metal substitution in Cu-BTC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sava Gallis, Dorina F.; Parkes, Marie V.; Greathouse, Jeffery A.; Zhang, Xiaoyi; Nenoff, Tina M.

    2015-03-05

    Here we describe the homogeneous substitution of Mn, Fe and Co at various levels into a prototypical metal-organic framework (MOF), namely Cu-BTC (HKUST-1), and the effect of that substitution on preferential gas sorption. Using a combination of density functional theory (DFT) calculations, postsynthetic metal substitutions, materials characterization, and gas sorption testing, we demonstrate that the identity of the metal ion has a quantifiable effect on their oxygen and nitrogen sorption properties at cryogenic temperatures. An excellent correlation is found between O2/N2 selectivities determined experimentally at 77 K and the difference in O2 and N2 binding energies calculated from DFT modelingmore » data: Mn > Fe > Co > Cu. Room temperature gas sorption studies were also performed and correlated with metal substitution. The Fe-exchanged sample shows a significantly higher nitrogen isosteric heat of adsorption at temperatures close to ambient conditions (273 K - 298 K) as compared to all other metals studied, indicative of favorable interactions between N2 and coordinatively unsaturated Fe metal centers. Furthermore, differences in gas adsorption results at cryogenic and room temperatures are evident; they are explained by comparing experimental results with DFT binding energies (0 K) and room temperature Grand Canonical Monte Carlo simulations.« less

  7. Redox Active Layer-by-Layer Structures containing MnO2 Nanoparticles

    SciTech Connect (OSTI)

    Bazito, Fernanda; O'Brien, Robert; Buttry, Daniel A.

    2005-02-01

    Nanoscale materials provide unique properties that will enable new technologies and enhance older ones. One area of intense activity in which nanoscale materials are being used is in the development of new functional materials for battery applications. This effort promises superior materials with properties that circumvent many of the problems associated with traditional battery materials. Previously we have worked on several approaches for using nanoscale materials for application as cathode materials in rechargeable Li batteries. Our recent work has focused on synthesizing MnO2 nanoparticles and using these in layer-by-layer (LbL) structures to probe the redox properties of the nanoparticles. We show that the aqueous colloidal nanoparticles produced by butanol reduction of tetramethylammonium permanganate can be trapped in thin films using a layer-by-layer deposition approach, and that these films are both redox active and exhibit kinetically facile electrochemical responses. We show cyclic voltammetry of MnO2 colloidal nanoparticles entrapped in a LbL thin film at an ITO electrode surface using poly(diallyldimethylammonium chloride) (PDDA). CV experiments demonstrate that Li+ insertion accompanies Mn(IV) reduction in LiClO4 supporting electrolytes, and that reduction is hindered in supporting electrolytes containing only tetrabutylammonium cations. We also show that electron propagation through multilayer films is facile, suggesting that electrons percolate through the films via electron exchange between nanoparticles.

  8. New Insights into Reaction Mechanisms of Ethanol Steam Reforming on Co-ZrO2

    SciTech Connect (OSTI)

    Sun, Junming; Karim, Ayman M.; Mei, Donghai; Engelhard, Mark H.; Bao, Xinhe; Wang, Yong

    2015-01-01

    The reaction pathway of ethanol steam reforming on Co-ZrO2 has been identified and the active sites associated with each step are proposed. Ethanol is converted to acetaldehyde and then to acetone, followed by acetone steam reforming. More than 90% carbon was found to follow this reaction pathway. N2-Sorption, X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR), in situ X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy, as well as theoretical Density Functional Theory (DFT) calculations have been employed to identify the structure and functionality of the catalysts, which was further used to correlate their performance in ESR. It was found that metallic cobalt is mainly responsible for the acetone steam reforming reactions; while, CoO and basic sites on the support play a key role in converting ethanol to acetone via dehydrogenation and condensation/ketonization reaction pathways. The current work provides fundamental understanding of the ethanol steam reforming reaction mechanisms on Co-ZrO2 catalysts and sheds light on the rational design of selective and durable ethanol steam reforming catalysts.

  9. Theoretical Study of Trimethylacetic Acid Adsorption on CeO 2 (111) Surface

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Weina; Thevuthasan, S.; Wang, Wenliang; Yang, Ping

    2016-01-11

    We investigated trimethylacetic acid (TMAA) adsorption on stoichiometric and oxygen-deficient CeO2(111) surfaces using density functional theory that accounts for the on-site Coulomb interaction via a Hubbard term (DFT+U) and long-range dispersion correction. Both the molecular state and dissociative state (TMAA → TMA– + H+) were identified on stoichiometric and oxygen-deficient CeO2(111) surfaces. For the stoichiometric surface, two thermodynamically favorable configurations with adsorption energies of the order of -30 kcal/mol are identified; one is a molecule adsorption state, and the other one is a dissociative state. For the oxygen-deficient surface, dissociative states are more favorable than molecular states. Moreover, the mostmore » favorable configuration is the dissociative adsorption of TMAA with the adsorption energy of the order of -77 kcal/mol. The dissociated TMA moiety takes the position of oxygen vacancy, forming three Ce–O bonds. The signature vibrational frequencies for these thermodynamically stable structures are reported as well as their electronic structures. The effects of long-range dispersion interactions are found to be negligible for geometries but important for adsorption energies.« less

  10. In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode

    SciTech Connect (OSTI)

    Huang, J. Y.; Zhong, Li; Wang, Chong M.; Sullivan, John P.; Xu, Wu; Zhang, Li Q.; Mao, Scott; Hudak, N.; Liu, Xiao H.; Subramanian, Arun Kumar; Fan, Hongyou; Qi, Liang; Kushima, Akihiro; Li, Ju

    2010-11-18

    We report the first real-time transmission electron microscopy (TEM) observations of the structural evolution and phase transformation of lithium-ion battery anode during the battery charging process. A nanobattery consisting of a single SnO2 nanowire anode and an ionic liquid electrolyte was successfully constructed in a TEM. We observed that during the charging process, the SnO2 crystal was converted to Li2O glass with LixSn nanocrystalline precipitates as the reaction front propagated progressively along the nanowire. After the reaction front passed, the nanowire showed swelling, elongation, and large off-axis distortion (spiraling). Upon completion of the electrochemical charging, the nanowire showed up to 120% elongation and a 30% increase in diameter with a volume expansion of about 272%. The charging front, which separates the reacted and unreacted sections of the nanowire, contains a high density of mobile dislocations, which are continuously nucleated and annihilated at the moving reaction front. This dislocation cloud indicates large in-plane misfit stresses, and serves as structural precursor to the eventual complete solid-state amorphization. The rate of charging in our nanobatteries is found to be proportional to the inverse square root of nanowire length, indicating that a standalone nanobattery or integrated arrays of nanobatteries should have kinetic advantage over conventional battery design. The present observations also provide important mechanistic insights for the design of advanced batteries with improved performance and lifetime for broad electrical energy storage applications.

  11. Electrolyte Concentration Effect of a Photoelectrochemical Cell Consisting of TiO 2 Nanotube Anode

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ren, Kai; Gan, Yong X.; Nikolaidis, Efstratios; Sofyani, Sharaf Al; Zhang, Lihua

    2013-01-01

    The photoelectrochemical responses of a TiO 2 nanotube anode in ethylene glycol (EG), glycerol, ammonia, ethanol, urea, and Na 2 S electrolytes with different concentrations were investigated. The TiO 2 nanotube anode was highly efficient in photoelectrocatalysis in these solutions under UV light illumination. The photocurrent density is obviously affected by the concentration change. Na 2 S generated the highest photocurrent density at 0, 1, and 2 V bias voltages, but its concentration does not significantly affect the photocurrent density. Urea shows high open circuit voltage at proper concentration and low photocurrent at different concentrations. Externally applied bias voltage ismore » also an important factor that changes the photoelectrochemical reaction process. In view of the open circuit voltage, EG, ammonia, and ethanol fuel cells show the trend that the open circuit voltage (OCV) increases with the increase of the concentration of the solutions. Glycerol has the highest OCV compared with others, and it deceases with the increase in the concentration because of the high viscosity. The OCV of the urea and Na 2 S solutions did not show obvious concentration effect.« less

  12. On the consistency of QCBED structure factor measurements for TiO2 (Rutile)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jiang, Bin; Zuo, Jian -Min; Friis, Jesper; Spence, John C. H.

    2003-09-16

    The same Bragg reflection in TiO2 from twelve different CBED patterns (from different crystals, orientations and thicknesses) are analysed quantitatively in order to evaluate the consistency of the QCBED method for bond-charge mapping. The standard deviation in the resulting distribution of derived X-ray structure factors is found to be an order of magnitude smaller than that in conventional X-ray work, and the standard error (0.026% for FX(110)) is slightly better than obtained by the X-ray Pendellosung method applied to silicon. This is sufficiently accuracy to distinguish between atomic, covalent and ionic models of bonding. We describe the importance of extractingmoreexperimental parameters from CCD camera characterization, and of surface oxidation and crystal shape. Thus, the current experiments show that the QCBED method is now a robust and powerful tool for low order structure factor measurement, which does not suffer from the large extinction (multiple scattering) errors which occur in inorganic X-ray crystallography, and may be applied to nanocrystals. Our results will be used to understand the role of d electrons in the chemical bonding of TiO2.less

  13. Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on (001) ceria

    SciTech Connect (OSTI)

    Solovyov, VF; Wu, LJ; Rupich, MW; Sathyamurthy, S; Li, XP; Li, Q

    2014-12-15

    Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO2 deposit. Second, vertical SnO2 nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 mu m long nano-rods with an average diameter of approximate to 20 nm. 2014 Elsevier B.V. All rights reserved.

  14. Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on(001) ceria

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Solovyov, Vyacheslav F.; Wu, Li-jun; Rupich, Martin W.; Sathyamurthy, Srivatsan; Li, Xiaoping; Li, Qiang

    2014-09-20

    Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO2 deposit. Second, vertical SnO2nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 μm long nano-rods with an average diameter of ≈20 nm.

  15. Increased photocatalytic activity of TiO2 mesoporous microspheres from codoping with transition metals and nitrogen

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mathis, John E.; Lieffers, Justin J.; Mitra, Chandrima; Reboredo, Fernando A.; Bi, Z.; Bridges, Craig A.; Kidder, Michelle K.; Paranthaman, Mariappan Parans

    2015-11-06

    The composition of anatase TiO2 was modified by codoping using combinations of a transition metal and nitrogen in order to increase its photocatalytic activity and extend it performance in the visible region of the electromagnetic spectrum. The transition metals (Mn, Co, Ni, Cu) were added during the hydrothermal preparation of mesoporous TiO2 particles, and the nitrogen was introduced by post-annealing in flowing ammonia gas at high temperature. The samples were analyzed by SEM, XRD, BET, inductively-coupled plasma spectroscopy, and diffuse reflectance UV-vis spectroscopy. The photocatalytic activity was assessed by observing the change in methylene blue concentrations under both UV-vis andmore » visible-only light irradiation. As a result, the photocatalytic activity of the (Mn,N), (Co,N), (Cu,N), and Ni,N) codoped TiO2 was significantly enhanced relative to (N) TiO2.« less

  16. A three-dimensional Macroporous Cu/SnO2 composite anode sheet prepared via a novel method

    SciTech Connect (OSTI)

    Xu, Wu; Canfield, Nathan L.; Wang, Deyu; Xiao, Jie; Nie, Zimin; Zhang, Jiguang

    2010-11-01

    Macroporous Cu/SnO2 composite anode sheets were prepared by a novel method which is based on slurry blending, tape casting, sintering, and reducing of metal oxides. Such composite Cu/SnO2 anode sheets have no conducting carbons and binders, and show improved discharge capacity and cycle life than the SnO2 electrode from conventional tape-casting method on Cu foil. This methodology produces limited wastes and is also adaptable to many other materials. It is easy for industrial scale production. With the optimization of particle size of the metal oxide, pore size, pore volume and other factors, this kind of macroporous Cu/SnO2 composite anode sheets could give significantly improved capacity and cycle life.

  17. Vehicle Technologies Office Merit Review 2015: Efficient Rechargeable Li/O2 Batteries Utilizing Stable Inorganic Molten Salt Electrolytes

    Broader source: Energy.gov [DOE]

    Presentation given by Liox at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about efficient rechargeable Li/O2 batteries...

  18. In Situ Time-Resolved Characterization of Ni-MoO2 Catalysts for the Water-Gas Shift Reaction

    SciTech Connect (OSTI)

    Wen,W.; Calderon, J.; Brito, J.; Marinkovic, N.; Hanson, J.; Rodriquez, J.

    2008-01-01

    Active catalysts for the water-gas shift (WGS, CO + H2O ? H2 + CO2) reaction were synthesized from nickel molybdates ({beta}-NiMoO4 and nH2O{center_dot}NiMoO4) as precursors, and their structural transformations were monitored using in situ time-resolved X-ray diffraction and X-ray absorption near-edge spectroscopy. In general, the nickel molybdates were not stable and underwent partial reduction in the presence of CO or CO/H2O mixtures at high temperatures. The interaction of {beta}-NiMoO4 with the WGS reactants at 500 C led to the formation of a mixture of Ni (24 nm particle size) and MoO2 (10 nm particle size). These Ni-MoO2 systems displayed good catalytic activity at 350, 400, and 500 C. At 350 and 400 C, catalytic tests revealed that the Ni-MoO2 system was much more active than isolated Ni (some activity) or isolated MoO2 (negligible activity). Thus, cooperative interactions between the admetal and oxide support were probably responsible for the high WGS activity of Ni-MoO2. In a second synthetic approach, the NiMoO4 hydrate was reduced to a mixture of metallic Ni, NiO, and amorphous molybdenum oxide by direct reaction with H2 gas at 350 C. In the first pass of the water-gas shift reaction, MoO2 appeared gradually at 500 C with a concurrent increase of the catalytic activity. For these catalysts, the particle size of Ni (4 nm) was much smaller than that of the MoO2 (13 nm). These systems were found to be much more active WGS catalysts than Cu-MoO2, which in turn is superior to commercial low-temperature Cu-ZnO catalysts.

  19. Nanoscale Laser-Induced Spallation in SiO2 Films Containing Gold Nanoparticles

    SciTech Connect (OSTI)

    Kudryashov, S.I.; Allen, S.D.; Papernov, S.; Schmid, A.W.

    2006-02-16

    A phenomenological theory of ultraviolet pulsed-laser-induced spallation is proposed to interpret crater formation in SiO2 thin films containing absorbing 18.5-nm gold particles. The theory considers a spherical thermoacoustic stress wave propagating from a thermal source produced by laser-energy absorption inside the particle and surrounding ionized volume. Calculations show that the tensile stress associated with such an acoustic wave may exceed the local strength of the material and cause fracture and spallation of the top film portion. The theory provides an explanation of the experimentally observed complex (two-cone) shape of craters formed in the film with particle-lodging depth exceeding 110 nm. Theoretical estimates for the threshold stress amplitude and peak temperature in the thermal source are in qualitative agreement with the experimental observations.

  20. Nucleation and Growth of Crystalline Grains in RF-Sputtered TiO 2 Films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Johnson, J. C.; Ahrenkiel, S. P.; Dutta, P.; Bommisetty, V. R.

    2009-01-01

    Amore » morphous TiO 2 thin films were radio frequency sputtered onto siliconmonoxide and carbon support films on molybdenum transmission electron microscope (TEM) grids and observed during in situ annealing in a TEM heating stage at 250 ∘ C. The evolution of crystallization is consistent with a classical model of homogeneous nucleation and isotropic grain growth. The two-dimensional grain morphology of the TEM foil allowed straightforward recognition of amorphous and crystallized regions of the films, for measurement of crystalline volume fraction and grain number density. By assuming that the kinetic parameters remain constant beyond the onset of crystallization, the final average grain size was computed, using an analytical extrapolation to the fully crystallized state. Electron diffraction reveals a predominance of the anatase crystallographic phase.« less

  1. Nucleation and Growth of Crystalline Grains in RF-Sputtered TiO2Films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Johnson, J. C.; Ahrenkiel, S. P.; Dutta, P.; Bommisetty, V. R.

    2009-01-01

    AmorphousTiO2thin films were radio frequency sputtered onto siliconmonoxide and carbon support films on molybdenum transmission electron microscope (TEM) grids and observed during in situ annealing in a TEM heating stage at250?C. The evolution of crystallization is consistent with a classical model of homogeneous nucleation and isotropic grain growth. The two-dimensional grain morphology of the TEM foil allowed straightforward recognition of amorphous and crystallized regions of the films, for measurement of crystalline volume fraction and grain number density. By assuming that the kinetic parameters remain constant beyond the onset of crystallization, the final average grain size was computed, using an analyticalmoreextrapolation to the fully crystallized state. Electron diffraction reveals a predominance of the anatase crystallographic phase.less

  2. Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Berardo, Enrico; Hu, Han -Shi; van Dam, Hubertus J. J.; Shevlin, Stephen A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

    2014-02-26

    We have investigated the description of excited state relaxation in naked and hydrated TiO2 nanoparticles using Time-Dependent Density Functional Theory (TD-DFT) with three common hybrid exchange-correlation (XC) potentials; B3LYP, CAM-B3LYP and BHLYP. Use of TD-CAM-B3LYP and TD-BHLYP yields qualitatively similar results for all structures, which are also consistent with predictions of coupled cluster theory for small particles. TD-B3LYP, in contrast, is found to make rather different predictions; including apparent conical intersections for certain particles that are not observed with TD-CAM-B3LYP nor with TD-BHLYP. In line with our previous observations for vertical excitations, the issue with TD-B3LYP appears to be themore » inherent tendency of TD-B3LYP, and other XC potentials with no or a low percentage of Hartree-Fock Like Exchange, to spuriously stabilize the energy of charge-transfer (CT) states. Even in the case of hydrated particles, for which vertical excitations are generally well described with all XC potentials, the use of TD-B3LYP appears to result in CT-problems for certain particles. We hypothesize that the spurious stabilization of CT-states by TD-B3LYP even may drive the excited state optimizations to different excited state geometries than those obtained using TD-CAM-B3LYP or TD-BHLYP. In conclusion, focusing on the TD-CAM-B3LYP and TD-BHLYP results, excited state relaxation in naked and hydrated TiO2 nanoparticles is predicted to be associated with a large Stokes’ shift.« less

  3. Striving toward noble-metal-free photocatalytic water splitting: The hydrogenated-graphene-TiO2 prototype

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nguyen-Phan, Thuy -Duong; Luo, Si; Liu, Zongyuan; Gamalski, Andrew D.; Tao, Jing; Xu, Wenqian; Stach, Eric A.; Polyansky, Dmitry E.; Senanayake, Sanjaya D.; Fujita, Etsuko; et al

    2015-08-20

    Graphane, graphone and hydrogenated graphene (HG) have been extensively studied in recent years due to their interesting properties and potential use in commercial and industrial applications. The present study reports investigation of hydrogenated graphene/TiO2-x (HGT) nanocomposites as photocatalysts for H2 and O2 production from water without the assistance of a noble metal co-catalyst. By combination of several techniques, the morphologies, bulk/atomic structure and electronic properties of all the powders were exhaustively interrogated. Hydrogenation treatment efficiently reduces TiO2 nanoparticles, while the graphene oxide sheets undergo the topotactic transformation from a graphene-like structure to a mixture of graphitic and turbostratic carbon (amorphous/disordered)more » upon altering the calcination atmosphere from a mildly reducing to a H2-abundant environment. Remarkably, the hydrogenated graphene-TiO2-x composite that results upon H2-rich reduction exhibits the highest photocatalytic H2 evolution performance equivalent to low loading of Pt (~0.12 wt%), whereas the addition of HG suppresses the O2 production. As a result, we propose that such an enhancement can be attributed to a combination of factors including the introduction of oxygen vacancies and Ti3+ states, retarding the recombination of charge carriers and thus, facilitating the charge transfer from TiO2-x to the carbonaceous sheet.« less

  4. Ammonia formation from NO reaction with surface hydroxyls on rutile TiO2 (110) - 11

    SciTech Connect (OSTI)

    Kim, Boseong; Kay, Bruce D.; Dohnalek, Zdenek; Kim, Yu Kwon

    2015-01-15

    The reaction of NO with hydroxylated rutile TiO2(110)-11 surface (h-TiO2) was investigated as a function of NO coverage using temperature-programmed desorption. Our results show that NO reaction with h-TiO2 leads to formation of NH3 which is observed to desorb at ~ 400 K. Interestingly, the amount of NH3 produced depends nonlinearly on the coverage of NO. The yield increases up to a saturation value of ~1.31013 NH3/cm2 at a NO dose of 51013 NO/cm2, but subsequently decreases at higher NO doses. Preadsorbed H2O is found to have a negligible effect on the NH3 desorption yield. Additionally, no NH3 is formed in the absence of surface hydroxyls (HObs) upon coadsorption of NO and H2O on a stoichiometric TiO2(110) (s-TiO2(110)). Based on these observations, we conclude that nitrogen from NO has a strong preference to react with HObs on the bridge-bonded oxygen rows (but not with H2O) to form NH3. The absolute NH3 yield is limited by competing reactions of HOb species with titanium-bound oxygen adatoms to form H2O. Our results provide new mechanistic insight about the interactions of NO with hydroxyl groups on TiO2(110) .

  5. Electrochemically synthesized ordered TiO2 and platinum nanocomposite electrode: preparation, characterization, and application to photoelectrocatalytic methanol oxidation

    SciTech Connect (OSTI)

    Li, Zhizhou; Cui, Xiaoli; Lin, Yuehe

    2009-04-01

    In this work, the nanocomposite electrodes consisting of Pt and TiO2 nanotubular arrays have been synthesized, and the morphologies, structural, and photo-electrochemical properties of the electrodes are characterized by SEM, XRD, and electrochemical methods. Highly ordered TiO2 nanotubular arrays can be obtained through anodization of titanium. The platinum nanoparticles are electrodeposited into TiO2 nanotubes by a chronopotentiometry method. Cyclic voltammetry and XRD measurements can confirm the presence of platinum in this nanocomposite electrode. The nanostructural electrode greatly improved performances for methanol oxidation under UV-Vis illumination compared to that without illumination. An enhancement of 58% in the current density has been observed upon illumination with UV-Vis light irradiance at an intensity of 50 mW/cm2. The improved performance of the TiO2/Pt nanocomposite electrode results from a enhanced methanol oxidation by photo-generated holes in the TiO2 nanoarrays under illumination and a synergistic effectiveness between TiO2 and Pt nanoparticles.

  6. Efficiency of clay-TiO2 nanocomposites on the photocatalytic eliminationof a model hydrophobic air pollutant

    SciTech Connect (OSTI)

    Kibanova, Daria; Cervini-Silva, Javiera; Destaillats, Hugo

    2009-01-01

    Clay-supported TiO2 photocatalysts can potentially improve the performance of air treatment technologies via enhanced adsorption and reactivity of target volatile organic compounds (VOCs). In this study, a bench-top photocatalytic flow reactor was used to evaluate the efficiency of hectorite-TiO2 and kaolinite-TiO2, two novel composite materials synthesized in our laboratory. Toluene, a model hydrophobic VOC and a common indoor air pollutant, was introduced in the air stream at realistic concentrations, and reacted under UVA (gamma max = 365 nm) or UVC (gamma max = 254 nm) irradiation. The UVC lamp generated secondary emission at 185 nm, leading to the formation of ozone and other short-lived reactive species. Performance of clay-TiO2 composites was compared with that of pure TiO2 (Degussa P25), and with UV irradiation in the absence of photocatalyst under identical conditions. Films of clay-TiO2 composites and of P25 were prepared by a dip-coating method on the surface of Raschig rings, which were placed inside the flow reactor. An upstream toluene concentration of ~;;170 ppbv was generated by diluting a constant flow of toluene vapor from a diffusion source with dry air, or with humid air at 10, 33 and 66percent relative humidity (RH). Toluene concentrations were determined by collecting Tenax-TA (R) sorbent tubes downstream of the reactor, with subsequent thermal desorption -- GC/MS analysis. The fraction of toluene removed, percentR, and the reaction rate, Tr, were calculated for each experimental condition from the concentration changes measured with and without UV irradiation. Use of UVC light (UV/TiO2/O3) led to overall higher reactivity, which can be partially attributed to the contribution of gas phase reactions by short-lived radical species. When the reaction rate was normalized to the light irradiance, Tr/I gamma, the UV/TiO2 reaction under UVA irradiation was more efficient for samples with a higher content of TiO2 (P25 and Hecto-TiO2), but not for Kao-TiO2. In all cases, reaction rates peaked at 10percent RH, with Tr values between 10 and 50percent higher than those measured under dry air. However, a net inhibition was observed as RH increased to 33percent and 66percent, indicating that water molecules competed effectively with toluene for reactive surface sites and limited the overall photocatalytic conversion. Compared to P25, inhibition by co-adsorbed water was less significant for Kao-TiO2 samples, but was more dramatic for Hecto-TiO2 due to the high water uptake capacity of hectorite.

  7. Molecular-Level Insights into Photocatalysis from Scanning Probe Microscopy Studies on TiO2(110)

    SciTech Connect (OSTI)

    Henderson, Michael A.; Lyubinetsky, Igor

    2013-06-12

    The field of heterogeneous photocatalysis has grown considerably in the decades since Fujishima and Honda's ground-breaking publications of photoelectrochemistry on TiO2. Numerous review articles continue to point to both progress made in the use of heterogeneous materials (such as TiO2) to perform photoconversion processes, and the many opportunities and challenges in heterogeneous photocatalysis research such as solar energy conversion and environmental remediation. The past decade has also seen an increase in the use of molecular-level approaches applied to model single crystal surfaces in an effort to obtain new insights into photocatalytic phenomena. In particular, scanning probe techniques (SPM) have enabled researchers to take a nanoscale approach to photocatalysis that includes interrogation of the reactivities of specific sites and adsorbates on a model photocatalyst surface. The rutile TiO2(110) surface has become the prototypical oxide single crystal surface for fundamental studies of many interfacial phenomena. In particular, TiO2(110) has become an excellent model surface for probing photochemical and photocatalytic reactions at the molecular level. A variety of experimental approaches have emerged as being ideally suited for studying photochemical reactions on TiO2(110), including desorption-oriented approaches and electronic spectroscopies, but perhaps the most promising techniques for evaluating site-specific properties are those of SPM. In this review, we highlight the growing use of SPM techniques in providing molecular-level insights into surface photochemistry on the model photocatalyst surface of rutile TiO2(110). Our objective is to both illustrate the unique knowledge that scanning probe techniques have already provided the field of photocatalysis, and also to motivate a new generation of effort into the use of such approaches to obtain new insights into the molecular level details of photochemical events occurring at interfaces. Discussion will start with an examination of how scanning probe techniques are being used to characterize the TiO2(110) surface in ways that are relevant to photocatalysis. We will then discuss specific classes of photochemical reaction on TiO2(110) for which SPM has proven indispensible in providing unique molecular-level insights, and conclude with discussion of future areas in which SPM studies may prove valuable to photocatalysis on TiO2. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. I.L. was partially supported by a Pacific Northwest National Laboratory (PNNL) Chemical Imaging Initiative project. PNNL is a multiprogram national laboratory operated for DOE by Battelle.

  8. Structure of epitaxial (Fe,N) codoped rutile TiO2 thin films by x-ray absorption

    SciTech Connect (OSTI)

    Kaspar, Tiffany C.; Ney, A.; Mangham, Andrew N.; Heald, Steve M.; Joly, Yves; Ney, V.; Wilhelm, F.; Rogalev, A.; Yakou, Flora; Chambers, Scott A.

    2012-07-23

    Homoepitaxial thin films of Fe:TiO2 and (Fe,N):TiO2 were deposited on rutile(110) by molecular beam epitaxy. X-ray absorption near edge spectroscopy (XANES) spectra were collected at the Ti L-edge, Fe L-edge, O K-edge, N K-edge, and Ti K-edge. No evidence of structural disorder associated with a high concentration of oxygen vacancies is observed. Substitution of Fe for Ti could not be confirmed, although secondary phase Fe2O3 and metallic Fe can be ruled out. The similarity of the N K-edge spectra to O, and the presence of a strong x-ray linear dichroism (XLD) signal for the N K-edge, indicates that N is substitutional for O in the rutile lattice, and is not present as a secondary phase such as TiN. Simulations of the XANES spectra qualitatively confirm substitution, although N appears to be present in more than one local environment. Neither Fe:TiO2 nor (Fe,N):TiO2 exhibit intrinsic room temperature ferromagnetism, despite the presence of mixed valence Fe(II)/Fe(III) in the reduced (Fe,N):TiO2 film.

  9. Interaction of cesium adatoms with free-standing graphene and graphene-veiled SiO2 surfaces

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Weck, Philippe F.; Kim, Eunja; Biedermann, Grant W.

    2015-04-21

    The interaction of Cs adatoms with mono- or bi-layered graphene (MLG and BLG), either free-standing or on a SiO2 substrate, was investigated using density functional theory. The most stable adsorption sites for Cs are found to be hollow sites on both graphene sheets and graphene-veiled SiO2(0001). In addition, larger dipole moments are created when a MLG-veiled SiO2(0001) substrate is used for adsorption of Cs atoms compared to the adsorption on free-standing MLG, due to charge transfer occurring between the MLG and the SiO2 substrate. For the adsorption of Cs on BLG-veiled SiO2(0001) substrate, these differences are smoothed out and themore » binding energies corresponding to different sites are nearly degenerate; smaller dipole moments created by the Cs adatoms on BLG compared to MLG are also predicted.« less

  10. Imaging Hindered Rotations of Alkoxy Species on TiO2(110)

    SciTech Connect (OSTI)

    Zhang, Zhenrong; Rousseau, Roger J.; Gong, Jinlong; Kay, Bruce D.; Dohnalek, Zdenek

    2009-12-16

    We present the first study of the rotational dynamics of organic species on any oxide surface. Specifically, variable-temperature scanning tunneling microscopy (STM) and dispersion-corrected density functional theory are used to study the alkyl chain conformational disorder and dynamics of 1-, 2-, 3- and 4-octoxy on rutile TiO2(110). Initially, the geminate pairs of the octoxy and bridging hydroxyl species are created via octanol dissociation on bridging-oxygen (Ob) vacancy defects. The STM images provide time averaged snapshots of octoxy species rotating among multiple energetically nearly-degenerate configurations accessible at a given temperature. In the calculations we find that the underlying corrugated potential energy surface is a result of the interplay between attractive Van der Waals dispersion forces leading to weak attractive C...Ti and repulsive C...Ob interactions which lead to large barriers of 50-70kJmol-1 for the rotation of the octoxy alkyl chains across the Ob rows. In the presence of the germinal hydroxyl groups we find that the relative populations of the various conformations as well as the rotational barriers are perturbed by the presence of geminate hydroxyl due to additional C...hydroxyl repulsions.

  11. Level Alignment of a Prototypical Photocatalytic System: Methanol on TiO2(110)

    SciTech Connect (OSTI)

    Migani, Annapaola; Mowbray, Duncan J.; Iacomino, Amilcare; Zhao, Jin; Petek, Hrvoje

    2013-08-07

    Photocatalytic activity depends on the optimal alignment of electronic levels at the molecule? semiconductor interface. Establishing the level alignment experimentally is complicated by the uncertain chemical identity of the surface species. We address the assignment of the occupied and empty electronic levels for the prototypical photocatalytic system consisting of methanol on a rutile TiO2(110) surface. Using many-body quasiparticle (QP) techniques, we show that the frontier levels measured in UV photoelectron and two-photon photoemission spectroscopy experiments can be assigned to molecularly chemisorbed methanol rather than its dissociated product, the methoxy species. We find that the highest occupied molecular orbital of the methoxy species is much closer to the valence band maximum, suggesting why it is more photocatalytically active than the methanol molecule. We develop a general semiquantitative model for predicting many-body QP energies based on the electronic screening within the bulk, molecular, or vacuum regions of the wave functions at molecule?semiconductor interfaces.

  12. Ternary Pt/Rh/SnO2 Electrocatalysts for Oxidizing Ethanol to CO2

    SciTech Connect (OSTI)

    Kowal, A.; Li, M; Shao, M; Sasaki, K; Vukmirovic, M; Zhang, J; Marinkovic, N; Liu, P; Frenkel, A; Adzic, R

    2009-01-01

    Ethanol, with its high energy density, likely production from renewable sources and ease of storage and transportation, is almost the ideal combustible for fuel cells wherein its chemical energy can be converted directly into electrical energy. However, commercialization of direct ethanol fuel cells has been impeded by ethanol's slow, inefficient oxidation even at the best electrocatalysts1, 2. We synthesized a ternary PtRhSnO2/C electrocatalyst by depositing platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles that is capable of oxidizing ethanol with high efficiency and holds great promise for resolving the impediments to developing practical direct ethanol fuel cells. This electrocatalyst effectively splits the C-C bond in ethanol at room temperature in acid solutions, facilitating its oxidation at low potentials to CO2, which has not been achieved with existing catalysts. Our experiments and density functional theory calculations indicate that the electrocatalyst's activity is due to the specific property of each of its constituents, induced by their interactions. These findings help explain the high activity of Pt-Ru for methanol oxidation and the lack of it for ethanol oxidation, and point to the way to accomplishing the C-C bond splitting in other catalytic processes.

  13. Nanostructured Metal Carbides for Aprotic Li-O2 Batteries. New Insights into Interfacial Reactions and Cathode Stability

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kundu, Dipan; Black, Robert; Adams, Brian; Harrison, Katharine; Zavadil, Kevin R.; Nazar, Linda F.

    2015-05-01

    The development of nonaqueous Li–oxygen batteries, which relies on the reversible reaction of Li + O2 to give lithium peroxide (Li2O2), is challenged by several factors, not the least being the high charging voltage that results when carbon is typically employed as the cathode host. We report here on the remarkably low 3.2 V potential for Li2O2 oxidation on a passivated nanostructured metallic carbide (Mo2C), carbon-free cathode host. Furthermore, online mass spectrometry coupled with X-ray photoelectron spectroscopy unequivocally demonstrates that lithium peroxide is simultaneously oxidized together with the LixMoO3-passivated conductive interface formed on the carbide, owing to their close redoxmore » potentials. We found that the process rejuvenates the surface on each cycle upon electrochemical charge by releasing LixMoO3 into the electrolyte, explaining the low charging potential.« less

  14. Surface-structure sensitivity of CeO2 nanocrystals in photocatalysis and enhancing the reactivity with nanogold

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lei, Wanying; Zhang, Tingting; Gu, Lin; Liu, Ping; Rodriguez, José A.; Liu, Gang; Liu, Minghua

    2015-06-19

    Structure–function correlations are a central theme in heterogeneous (photo)catalysis. In this research, using aberration-corrected scanning transmission electron microscopy (STEM), the atomic surface structures of well-defined one-dimensional (1D) CeO2 nanorods (NRs) and 3D nanocubes (NCs) are directly visualized at subangstrom resolution. CeO2 NCs predominantly expose the {100} facet, with {110} and {111} as minor cutoff facets at the respective edges and corners. Notably, the outermost surface layer of the {100} facet is nearly O-terminated. Neither surface relaxations nor reconstructions on {100} are observed, indicating unusual polarity compensation, which is primarily mediated by near-surface oxygen vacancies. The surface of CeO2 NRs ismore » highly stepped, with the enclosed {110} facet exposing Ce cations and O anions on terraces. On the basis of STEM profile-view imaging and electronic structure analysis, the photoreactivity of CeO2 nanocrystals toward aqueous methyl orange degradation under UV is revealed to be surface-structure-sensitive, following the order: {110} >> {100}. The underlying surface-structure sensitivity can be attributed to the variation in low-coordinate surface cerium cations between {110} and {100} facets. To further enhance light absorption, Au nanoparticles (NPs) are deposited on CeO2 NRs to form Au/CeO2 plasmonic nanocomposites, which dramatically promotes the photoreactivity that is Au particle size- and excitation light wavelength-dependent. The mechanisms responsible for the enhancement of photocatalytic activity are discussed, highlighting the crucial role of photoexcited charge carrier transfer.« less

  15. Determination of the Surface Structure of CeO2(111) by Low-Energy Electron

    Office of Scientific and Technical Information (OSTI)

    Diffraction. (Journal Article) | SciTech Connect Determination of the Surface Structure of CeO2(111) by Low-Energy Electron Diffraction. Citation Details In-Document Search Title: Determination of the Surface Structure of CeO2(111) by Low-Energy Electron Diffraction. Abstract not provided. Authors: McCarty, Kevin F. ; Siegel, David A ; El Gabaly Marquez, Farid ; Chueh, William ; de la Figuera, Juan ; Blanco-Rey, Maria Publication Date: 2013-06-01 OSTI Identifier: 1113313 Report Number(s):

  16. The effect of f[subscript O2] on the partitioning and valence of V and Cr

    Office of Scientific and Technical Information (OSTI)

    in garnet/melt pairs and the relation to terrestrial mantle V and Cr content (Journal Article) | SciTech Connect Journal Article: The effect of f[subscript O2] on the partitioning and valence of V and Cr in garnet/melt pairs and the relation to terrestrial mantle V and Cr content Citation Details In-Document Search Title: The effect of f[subscript O2] on the partitioning and valence of V and Cr in garnet/melt pairs and the relation to terrestrial mantle V and Cr content Chromium and vanadium

  17. Reactivity Screening of Anatase TiO2 Nanotube Arrays and Anatase Thin Films: A Surface Chemistry Point of View

    SciTech Connect (OSTI)

    Funk, S.; Hokkanen, B.; Nurkic, T.; Goering, J.; Kadossov, E.; Burghaus, Uwe; Ghicov, A.; Schmuki, P.; Yu, Zhongqing; Thevuthasan, Suntharampillai; Saraf, Laxmikant V.

    2008-09-19

    As a reactivity screening we collected thermal desorption spectroscopy (TDS) data of iso-butane, O2, CO2, and CO adsorbed on ordered TiO2 nanotube (TiNTs) arrays. As a reference system iso-butane adsorption on an anatase TiO2 thin film has been considered as well. The as-grown TiNTs are vertically aligned and amorphous. Polycrystalline (poly.) anatase or poly. anatase/rutile mixed nanotubes are formed by annealing confirmed by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The anatase thin film was grown on SrTiO3(001) and characterized by XRD and atomic force microscopy (AFM). Surprisingly, oxygen distinctly interacts with the TiNTs whereas this process is not observed on fully oxidized single crystal rutile TiO2(110). Desorption temperatures of 110-150 K and 100-120 K were observed for CO2 and CO, respectively, on the TiNTs. Variations in the binding energies of the alkanes on TiNTs and anatase thin films also were present, i.e., a structure-activity relationship (SAR) is evident.

  18. Constructing hierarchical interfaces: TiO2-supported PtFe-FeOx nanowires for room temperature CO oxidation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhu, Huiyuan; Wu, Zili; Dong, Su; Veith, Gabriel M.; Lu, Hanfeng; Zhang, Pengfei; Chai, Song -Hai; Dai, Sheng

    2015-08-05

    This is a report of a facile approach to constructing catalytic active hierarchical interfaces in one-dimensional (1D) nanostructure, exemplified by the synthesis of TiO2-supported PtFe–FeOx nanowires (NWs). The hierarchical interface, constituting atomic level interactions between PtFe and FeOx within each NW and the interactions between NWs and support (TiO2), enables CO oxidation with 100% conversion at room temperature. We identify the role of the two interfaces by probing the CO oxidation reaction with isotopic labeling experiments. Both the oxygen atoms (Os) in FeOx and TiO2 participate in the initial CO oxidation, facilitating the reaction through a redox pathway. Moreover, themore » intact 1D structure leads to the high stability of the catalyst. After 30 h in the reaction stream, the PtFe–FeOx/TiO2 catalyst exhibits no activity decay. These results provide a general approach and new insights into the construction of hierarchical interfaces for advanced catalysis.« less

  19. TiO2 nanotube arrays grown in ionic liquids: high-efficiency in photocatalysis and pore-widening

    SciTech Connect (OSTI)

    Li, Huaqing; Qu, Jun; Cui, Qingzhou; Xu, Hanbing; Luo, Huimin; Chi, Miaofang; Meisner, Roberta Ann; Wang, Wei; Dai, Sheng

    2011-01-01

    Debris-free, long, well-separated TiO2 nanotube arrays were obtained using an ionic liquid (IL) as electrolyte. The high conductivity of IL resulted in fast pore widening and few contaminants from electrolyte decomposition leading to high photocatalytic efficiency in water splitting.

  20. Highly Active TiO2-Based Visible-Light Photocatalyst with Nonmetal Doping and Plasmonic Metal Decoration

    SciTech Connect (OSTI)

    Zhang, Qiao; Lima, Diana Q.; Chi, Miaofang; Yin, Yadong

    2011-01-01

    A sandwich-structured photocatalyst shows an excellent performance in degradation reactions of a number of organic compounds under UV, visible light, and direct sunlight (see picture). The catalyst was synthesized by a combination of nonmetal doping and plasmonic metal decoration of TiO2 nanocrystals, which improves visible-light activity and enhances light harvesting and charge separation, respectively.

  1. Successes and failures of Hubbard-corrected density functional theory. The case of Mg doped LiCoO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Santana Palacio, Juan A.; Kim, Jeongnim; Kent, Paul R.; Reboredo, Fernando A.

    2014-10-28

    We have evaluated the successes and failures of the Hubbard-corrected density functional theory approach to study Mg doping of LiCoO2. We computed the effect of the U parameter on the energetic, geometric, and electronic properties of two possible doping mechanisms: (1) substitution of Mg onto a Co (or Li) site with an associated impurity state and (2) formation of impurity-state-free complexes of substitutional Mg and point defects in LiCoO2. We find that formation of impurity states results in changes on the valency of Co in LiCoO2. Variation of the Co U shifts the energy of the impurity state, resulting inmore » energetic, geometric, and electronic properties that depend significantly on the specific value of U. In contrast, the properties of the impurity-state-free complexes are insensitive to U. These results identify reasons for the strong dependence on the doping properties on the chosen value of U and for the overall difficulty of achieving agreement with the experimentally known energetic and electronic properties of doped transition metal oxides such as LiCoO2.« less

  2. Multi-Timescale Investigation of Radiation Damage near TiO2 Rutile Grain Boundaries

    SciTech Connect (OSTI)

    Xian-Ming Bai; Blas P. Uberuaga

    2012-04-01

    Although grain boundaries (GBs) have been experimentally demonstrated to serve as sinks for absorbing radiation induced defects and improving the radiation tolerance of materials, the detailed atomistic interactions between defects and GBs leading to this enhanced tolerance are not well understood. In oxide ceramics the interactions are further complicated as defects can be charged and grain boundaries may exhibit space charge and charge dipole effects. Here, we use two atomistic modeling methods to examine the role of GBs in a model oxide system, rutile TiO2, in modifying defect production during irradiation events. The GB studied is a symmetric tilt GB with a rotation axis of [100] and a rotation angle of 15.25{sup o}. We use molecular dynamics to investigate defect production near the GB at both 300K and 1000 K and find that the damage production is sensitive to the initial distance of the primary knock-on atom (PKA) from the GB. We find three distinct regimes in which GBs have different effects on modifying defect production. Similar to GBs in metals, the GB absorbs more interstitials than vacancies at certain distances while this behavior of biased loading of interstitials diminishes at other distances. Further, we obtain the statistics of both interstitial and vacancy clusters 2 produced in collision cascades in terms of their compositions at two temperatures. We find that perfectly stoichiometric defect clusters (Schottky and anti-Schottky clusters) represent a small fraction of the total defect clusters produced. Moreover, a significant reduction in the number of interstitial clusters at 1000 K compared to 300 K is thought to be a consequence of enhanced migration of interstitials towards the GB. Finally the kinetic properties of certain defect clusters are investigated with temperature accelerated dynamics, without any priori assumptions of migration mechanisms. We find that small interstitial clusters become mobile at high temperatures while small vacancy clusters do not. Multiple migration pathways exist and are typically complex and non-intuitive. We use this kinetic information to explain experimental observations and predict their long-time migration behavior near GBs.

  3. Influence of particle size and water coverage on the thermodynamic properties of water confined on the surface of SnO2 cassiterite nanoparticles

    SciTech Connect (OSTI)

    Spencer, Elinor; Ross, Dr. Nancy; Parker, Stewart F.; Kolesnikov, Alexander I; Woodfield, Brian; Woodfield, K; Rytting, M; Boerio-Goates, Juliana; Navrotsky, Alexandra

    2011-01-01

    Inelastic neutron scattering (INS) data for SnO2 nanoparticles of three different sizes and varying hydration levels are presented. Data were recorded on five nanoparticle samples that had the following compositions: 2 nm SnO2*0.82H2O, 6 nm SnO2*0.055H2O, 6 nm SnO2*0.095H2O, 20 nm SnO2*0.072H2O, and 20 nm SnO2*0.092H2O. The isochoric heat capacity and vibrational entropy values at 298 K for the water confined on the surface of these nanoparticles were calculated from the vibrational density of states that were extracted from the INS data. This study has shown that the hydration level of the SnO2 nanoparticles influences the thermodynamic properties of the water layers and, most importantly, that there appears to be a critical size limit for SnO2 between 2 and 6 nm below which the particle size also affects these properties and above which it does not. These results have been compared with those for isostructural rutile-TiO2 nanoparticles [TiO2*0.22H2O and TiO2*0.37H2O], which indicated that water on the surface of TiO2 nanoparticles is more tightly bound and experiences a greater degree of restricted motion with respect to water on the surface of SnO2 nanoparticles. This is believed to be a consequence of the difference in chemical composition, and hence surface properties, of these metal oxide nanoparticles.

  4. Photo-catalytic oxidation of acetone on a TiO2 powder: An in situ FTIR investigation

    SciTech Connect (OSTI)

    Szanyi, Janos; Kwak, Ja Hun

    2015-09-01

    In situ transmission infrared spectroscopy was used to investigate the photo-oxidation of acetone on a commercial, oxidized TiO2 (P25) powder catalyst under UV irradiation at ambient temperature, in the absence and presence of gas phase O2. The photochemistry of a number of organic molecules (1-butanone, methanol and acetic acid,) under the same conditions was also studied in order to identify reaction intermediates and products formed in the photo-oxidation of acetone. Under anaerobic conditions (in the absence of gas phase oxygen) limited extent of photo-oxidation of acetone took place on the oxidized TiO2 sample. In the presence of O2 in the gas phase, however, acetone was completely converted to acetates and formates, and ultimately CO2. The initial step in the sequence of photo-induced reactions is the ejection of a methyl radical, resulting in the formation of surface acetates (from the acetyl group) and formates (from the methyl radicals). Acetate ions are also converted to formates, that, in turn, photo-oxidized to CO2. Under the experimental conditions applied the accumulation of carbonates and bicarbonates were observed on the TiO2 surface as the photo-oxidation of acetone proceeded (this was also observed during the course of photo-oxidation of all the other organics studied here). When the initial radical ejection step produced hydrocarbons containing more than one C atoms (as in the case in 2-butanone and mesytil oxide), the formation of aldehydes on the catalyst surface was also observed as a result of secondary reactions. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. JHK also acknowledges the support of this work by the 2014 Research Fund of UNIST (Ulsan National Institute of Science and Technology, Ulsan, Korea). The authors thank M.A. Henderson for the fruitful discussions on the photo-oxidation of organic molecules on TiO2.

  5. Epitaxial single-crystal thin films of MnxTi1-xO2-? grown on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory

    SciTech Connect (OSTI)

    Ilton, Eugene S.; Droubay, Timothy C.; Chaka, Anne M.; Kovarik, Libor; Varga, Tamas; Arey, Bruce W.; Kerisit, Sebastien N.

    2015-02-01

    Epitaxial rutile-structured single-crystal MnxTi1-xO2-? films were synthesized on rutile- (110) and -(001) substrates using pulsed laser deposition. The films were characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and aberration-corrected transmission electron microscopy (ACTEM). Under the present conditions, 400oC and PO2 = 20 mTorr, single crystal epitaxial thin films were grown for x = 0.13, where x is the nominal average mole fraction of Mn. In fact, arbitrarily thick films could be grown with near invariant Mn/Ti concentration profiles from the substrate/film interface to the film surface. In contrast, at x = 0.25, Mn became enriched towards the surface and a secondary nano-scale phase formed which appeared to maintain the basic rutile structure but with enhanced z-contrast in the tunnels, or tetrahedral interstitial sites. Ab initio thermodynamic calculations provided quantitative estimates for the destabilizing effect of expanding the ?-MnO2 lattice parameters to those of TiO2-rutile, the stabilizing effect of diluting Mn with increasing Ti concentration, and competing reaction pathways.

  6. The effects of zirconia morphology on methanol synthesis from COand H2 over Cu/ZrO2 catalysts: Part I -- Steady-State Studies

    SciTech Connect (OSTI)

    Rhodes, Michael J.; Bell, Alexis T.

    2005-03-21

    The effect of zirconia phase on the activity and selectivityof Cu/ZrO2 for the hydrogenation of CO has been investigated. Relativelypure t-ZrO2 and m-ZrO2 were prepared with high surface areas (~; 145m2/g). Copper was then deposited onto the surface of these materials byeither incipient-wetness impregnation or deposition-precipitation. For afixed Cu surface area, Cu/m-ZrO2 was tenfold more active for methanolsynthesis than Cu/t-ZrO2 from a feed of 3/1 H2/CO at 3.0 MPa andtemperatures between 473 and 523 K. Cu/m-ZrO2 also exhibited a higherselectivity to methanol. Increasing the Cu surface area on m-ZrO2resulted in further improvement in activity with minimal change inselectivity. Methanol productivity increased linearly for both Cu/t-ZrO2and Cu/m-ZrO2 with increasing Cu surface area. The difference in inherentactivity of each phase paralleled the stronger and larger CO adsorptioncapacity of the Cu/m-ZrO2 as quantified by CO-TPD. The higher COadsorption capacity of Cu/m-ZrO2 is attributed to the presence of a highconcentration of anionic vacancies on the surface of m-ZrO2. Suchvacancies expose cus-Zr4+ cations, which act as Lewis acid centers andenhance the Bronsted acidity of adjacent Zr-OH groups. The presence ofcus-Zr4+ sites and adjacent Bronsted acidic Zr-OH groups contributes tothe adsorption of CO as HCOO-Zr groups, which are the initial precursorsto methanol.

  7. Large-Scale Synthesis of Transition-Metal-Doped TiO2 Nanowires with Controllable Overpotential

    SciTech Connect (OSTI)

    Liu, Bin; Chen, HaoMing; Liu, Chong; Andrews, Sean; Han, Chris; Yang, Peidong

    2013-03-13

    Practical implementation of one-dimensional semiconductors into devices capable of exploiting their novel properties is often hindered by low product yields, poor material quality, high production cost, or overall lack of synthetic control. Here, we show that a molten-salt flux scheme can be used to synthesize large quantities of high-quality, single-crystalline TiO2 nanowires with controllable dimensions. Furthermore, in situ dopant incorporation of various transition metals allows for the tuning of optical, electrical, and catalytic properties. With this combination of control, robustness, and scalability, the molten-salt flux scheme can provide high-quality TiO2 nanowires to satisfy a broad range of application needs from photovoltaics to photocatalysis.

  8. Identification of the Active Species in Photochemical Hole Scavenging Reactions of Methanol on TiO2

    SciTech Connect (OSTI)

    Shen, Mingmin; Henderson, Michael A.

    2011-11-03

    Molecular and dissociative methanol adsorption species were prepared on rutile TiO2(110) surfaces to study photocatalytic oxidation of methanol in ultrahigh vacuum (UHV) using temperature-programmed desorption (TPD). Adsorbed methoxy groups (CH3O-) were found to be the photoactive form of adsorbed methanol converted to adsorbed formaldehyde and a surface OH group by hole-mediated C-H bond cleavage. These results suggest that adsorbed methoxy is the effective hole scavenger in photochemical reactions involving methanol.

  9. Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yang, Sang Mo; Lee, Shinbuhm; Jian, Jie; Zhang, Wenrui; Lu, Ping; Jia, Quanxi; Wang, Haiyan; Won Noh, Tae; Kalinin, Sergei V.; MacManus‐Driscoll, Judith L.

    2015-10-08

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2films. Then bymore » using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. Furthermore, this work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness.« less

  10. Site Competition During Coadsorption of Acetone with Methanol and Water on TiO2(110)

    SciTech Connect (OSTI)

    Shen, Mingmin; Henderson, Michael A.

    2011-08-02

    The competitive interaction between acetone and two solvent molecules (methanol and water) for surface sites on rutile TiO2(110) was studied using temperature programmed desorption (TPD). On a vacuum reduced TiO2(110) surface, which possessed ~5% oxygen vacancy sites, excess methanol displaced preadsorbed acetone molecules to weakly bound and physisorbed desorption states below 200 K, whereas acetone was stabilized to 250 K against displacement by methanol on an oxidized surface through formation of an acetone-diolate species. These behaviors of acetone differ from the competitive interactions between acetone and water in that acetone is less susceptible to displacement by water. Examination of acetone+methanol and acetone+water multilayer combinations shows that acetone is more compatible in water-ice films than in methanol-ice films, presumably because water has greater potential as a hydrogen-bond donor than does methanol. Acetone molecules displaced from the TiO2(110) surface by water are more likely to be retained in the near-surface region, having a greater opportunity to revisit the surface, than when methanol is used as a coadsorbate. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  11. A VUV photoionization measurement and ab-initio calculation of the ionization energy of gas phase SiO2

    SciTech Connect (OSTI)

    Kostko, Oleg; Ahmed, Musahid; Metz, Ricardo B.

    2008-12-05

    In this work we report on the detection and vacuum-ultraviolet (VUV) photoionization of gas phase SiO2 generated in situ via laser ablation of silicon in a CO2 molecular beam. The resulting species are investigated by single photon ionization with tunable VUV synchrotron radiation and mass analyzed using reflectron mass spectrometry. Photoionization efficiency (PIE) curves are recorded for SiO and SiO2 and ionization energy estimates are revealed from such measurements. A state-to-state ionizationenergy of 12.60 (+-0.05) eV is recorded by fitting two prominent peaks in the PIE curve for the following process: 1SUM O-Si-O --> 2PRODg [O-Si-O]+. Electronic structure calculations aid in the interpretation of the photoionization process and allow for identification of the symmetric stretch of 2PRODg [O-Si-O]+ which is observed in the PIE spectrum to be 0.11 eV (890 cm-1) above the ground state of the cation and agrees with the 892 cm-1 symmetric stretch frequency calculated at the CCSD(T)/aug-cc-pVTZ level.

  12. Compatibility of Lithium Salts with Solvent of the Non-Aqueous Electrolyte in LiO2 Batteries

    SciTech Connect (OSTI)

    Du, Peng; Lu, Jun; Lau, Kah Chun; Luo, Xiangyi; Bareno, Javier; Zhang, Xiaoyi; Ren, Yang; Zhang, Zhengcheng; Curtiss, Larry A.; Sun, Yang-Kook; Amine, Khalil

    2013-02-20

    The stability of lithium salts, especially in the presence of reduced oxygen species, O2 and H2O (even in a small amount), plays an important role in the cyclability and capacity of LiO2 cells. This combined experimental and computational study provides evidence that the stability of the electrolyte used in LiO2 cells strongly depends on the compatibility of lithium salts with solvent. In the case of the LiPF61NM3 electrolyte, the decomposition of LiPF6 occurs in the cell as evidenced by in situ XRD, FT-IR and XPS analysis, which triggers the decomposition of 1NM3 solvent due to formation of HF from the decomposition of LiPF6. These reactions lead to degradation of the electrolyte and cause poor cyclability of the cell. The same reactions are not observed when LiTFSI and LiCF3SO3 are used as the lithium salts in 1NM3 solvent, or LiPF6 is used in TEGDME solvent.

  13. Modeling of selected ceramic processing parameters employed in the fabrication of 238PuO2 fuel pellets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Brockman, R. A.; Kramer, D. P.; Barklay, C. D.; Cairns-Gallimore, D.; Brown, J. L.; Huling, J. C.; Van Pelt, C. E.

    2011-10-01

    Recent deep space missions utilize the thermal output of the radioisotope plutonium-238 as the fuel in the thermal to electrical power system. Since the application of plutonium in its elemental state has several disadvantages, the fuel employed in these deep space power systems is typically in the oxide form such as plutonium-238 dioxide (238PuO2). As an oxide, the processing of the plutonium dioxide into fuel pellets is performed via ''classical'' ceramic processing unit operations such as sieving of the powder, pressing, sintering, etc. Modeling of these unit operations can be beneficial in the understanding and control of processing parameters withmore » the goal of further enhancing the desired characteristics of the 238PuO2 fuel pellets. A finite element model has been used to help identify the time-temperature-stress profile within a pellet during a furnace operation taking into account that 238PuO2 itself has a significant thermal output. The results of the modeling efforts will be discussed.« less

  14. Remediation of Organic and Inorganic Arsenic Contaminated Groundwater using a Nonocrystalline TiO2 Based Adsorbent

    SciTech Connect (OSTI)

    Jing, C.; Meng, X; Calvache, E; Jiang, G

    2009-01-01

    A nanocrystalline TiO2-based adsorbent was evaluated for the simultaneous removal of As(V), As(III), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in contaminated groundwater. Batch experimental results show that As adsorption followed pseudo-second order rate kinetics. The competitive adsorption was described with the charge distribution multi-site surface complexation model (CD-MUSIC). The groundwater containing an average of 329 ?g L-1 As(III), 246 ?g L-1 As(V), 151 ?g L-1 MMA, and 202 ?g L-1 DMA was continuously passed through a TiO2 filter at an empty bed contact time of 6 min for 4 months. Approximately 11 000, 14 000, and 9900 bed volumes of water had been treated before the As(III), As(V), and MMA concentration in the effluent increased to 10 ?g L-1. However, very little DMA was removed. The EXAFS results demonstrate the existence of a bidentate binuclear As(V) surface complex on spent adsorbent, indicating the oxidation of adsorbed As(III). A nanocrystalline TiO2-based adsorbent could be used for the simultaneous removal of As(V), As(III), MMA, and DMA in contaminated groundwater.

  15. Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yang, Sangmo; Lee, Shinbuhm; Jian, Jie; Zhang, Wenrui; Lu, Ping; Jia, Quanxi; Wang, Haiyan; Noh, Tae Won; Kalinin, Sergei V.; MacManus-Driscoll, Judith L.

    2015-10-08

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2 films. Bymore » using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness.« less

  16. Effect of Oxygen Defects on the Catalytic Performance of VOx/CeO2 Catalysts for Oxidative Dehydrogenation of Methanol

    SciTech Connect (OSTI)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Baylon, Rebecca A.; Peden, Charles HF; Wang, Yong

    2015-05-01

    In this work, CeO2 nanocubes with controlled particle size and dominating (100) facets are synthesized as supports for VOx catalysts. Combined TEM, SEM, XRD, and Raman study reveals that the oxygen vacancy density of CeO2 supports can be tuned by tailoring the particle sizes without altering the dominating facets, where smaller particle sizes result in larger oxygen vacancy densities. At the same vanadium coverage, the VOx catalysts supported on small-sized CeO2 supports with higher oxygen defect densities exhibit promoted redox property and lower activation energy for methoxyl group decomposition, as evidenced by H2-TPR and methanol TPD study. These results further confirm that the presence of oxygen vacancies plays an important role in promoting the activity of VOx species in methanol oxidation. We gratefully acknowledge financial support from the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Part of this work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogram national laboratory operated for the DOE by Battelle.

  17. High-Tc superconductivity at the interface between the CaCuO2 and SrTiO3 insulating oxides

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Di Castro, D.; Cantoni, C.; Ridolfi, F.; Aruta, C.; Tebano, A.; Yang, N.; Balestrino, G.

    2015-09-28

    At interfaces between complex oxides it is possible to generate electronic systems with unusual electronic properties, which are not present in the isolated oxides. One important example is the appearance of superconductivity at the interface between insulating oxides, although, until now, with very low Tc. We report the occurrence of high Tc superconductivity in the bilayer CaCuO2/SrTiO3, where both the constituent oxides are insulating. In order to obtain a superconducting state, the CaCuO2/SrTiO3 interface must be realized between the Ca plane of CaCuO2 and the TiO2 plane of SrTiO3. Only in this case can oxygen ions be incorporated in themore » interface Ca plane, acting as apical oxygen for Cu and providing holes to the CuO2 planes. In addition, a detailed hole doping spatial profile can be obtained by scanning transmission electron microscopy and electron-energy-loss spectroscopy at the O K edge, clearly showing that the (super)conductivity is confined to about 1–2 CaCuO2 unit cells close to the interface with SrTiO3. The results obtained for the CaCuO2/SrTiO3 interface can be extended to multilayered high Tc cuprates, contributing to explaining the dependence of Tc on the number of CuO2 planes in these systems.« less

  18. Spontaneous formation of suboxidic coordination around Co in ferromagnetic rutile Ti0.95Co0.5O2 film

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hu, Wen; Hayaski, Kouichi; Fukumura, Tomoteru; Akagi, Kazuto; Tsukada, Masaru; Happo, Naohisa; Hosokawa, Shinya; Ohwada, Kenji; Takahasi, Masamitu; Suzuki, Motohiro; et al

    2015-06-02

    To evaluate local atomic structures around Co in high temperature diluted ferromagnetic semiconductor Co-doped TiO2, x-ray fluorescence holography and x-ray absorption fine structure experiments were carried out on rutile paramagnetic Ti0.99Co0.01O2 and ferromagnetic Ti0.95Co0.05O2 films. The Co atoms in the Ti0.99Co0.01O2 simply substituted for Ti sites in the rutile structure, whereas a suboxidic arrangement of CoO2Ti4 formed around Co in the Ti0.95Co0.05O2 films. A theoretical investigation based on a series of first-principles calculations indicated the stability of the aggregated suboxidic clusters in the rutile TiO2, supporting our hypothesis for the formation of suboxidic coordination in the highly Co-doped sample. Asmore » a result, the suboxidic coordination may be the source of strong exchange interaction, resulting in the high Curie temperature in Co-doped TiO2.« less

  19. Investigation of the Decomposition Mechanism of Lithium Bis(oxalate)borate (LiBOB) Salt in the Electrolyte of an Aprotic LiO2 Battery

    SciTech Connect (OSTI)

    Lau, Kah Chun; Lu, Jun; Low, John; Peng, Du; Wu, Huiming; Albishri, Hassan M.; Al-Hady, D. Abd; Curtiss, Larry A.; Amine, Khalil

    2014-04-01

    The stability of the lithium bis(oxalate) borate (LiBOB) salt against lithium peroxide (Li2O2) formation in an aprotic LiO2 (Liair) battery is investigated. From theoretical and experimental findings, we find that the chemical decomposition of LiBOB in electrolytes leads to the formation lithium oxalate during the discharge of a LiO2 cell. According to density functional theory (DFT) calculations, the formation of lithium oxalate as the reaction product is exothermic and therefore is thermodynamically feasible. This reaction seems to be independent of solvents used in the LiO2 cell, and therefore LiBOB is probably not suitable to be used as the salt in LiO2 cell electrolytes.

  20. Selective Binding of O2 over N2 in a Redox-Active Metal-Organic Framework

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with Open Iron(II) Coordination Sites | Center for Gas SeparationsRelevant to Clean Energy Technologies | Blandine Jerome Selective Binding of O2 over N2 in a Redox-Active Metal-Organic Framework with Open Iron(II) Coordination Sites Previous Next List E. D. Bloch, L. J. Murray, W. L. Queen, S. Chavan, S. N. Maximoff, J. P. Bigi, R. Krishna, V. K. Peterson, F. Grandjean, G. J. Long, B. Smit, S. Bordiga, C. M. Brown, and J. R. Long, J. Am. Chem. Soc. 133 (37), 14814 (2011) DOI:

  1. Radiation damage in cubic-ZrO2 and yttria-stabilized zirconia from molecular dynamics simulations

    SciTech Connect (OSTI)

    Aidhy, Dilpuneet S; Zhang, Yanwen; Weber, William J

    2015-01-01

    We perform molecular dynamics simulation on cubic ZrO2 and yttria-stabilized zirconia (YSZ) to elucidate defect cluster formation resulting from radiation damage, and evaluate the impact of Y-dopants. Interstitial clusters composed of split-interstitial building blocks, i.e., Zr-Zr or Y-Zr are formed. Oxygen vacancies control cation defect migration; in their presence, Zr interstitials aggregate to form split-interstitials whereas in their absence Zr interstitials remain immobile, as isolated single-interstitials. Y-doping prevents interstitial cluster formation due to sequestration of oxygen vacancies.

  2. Ab Initio Simulation of Charge Transfer at the Semiconductor Quantum Dot/TiO 2 Interface in Quantum Dot-Sensitized Solar Cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xin, Xukai; Li, Bo; Jung, Jaehan; Yoon, Young Jun; Biswas, Rana; Lin, Zhiqun

    2014-07-24

    Quantum dot-sensitized solar cells (QDSSCs) have emerged as a promising solar architecture for next-generation solar cells. The QDSSCs exhibit a remarkably fast electron transfer from the quantum dot (QD) donor to the TiO2 acceptor with size quantization properties of QDs that allows for the modulation of band energies to control photoresponse and photoconversion efficiency of solar cells. In order to understand the mechanisms that underpin this rapid charge transfer, the electronic properties of CdSe and PbSe QDs with different sizes on the TiO2 substrate are simulated using a rigorous ab initio density functional method. Our method capitalizes on localized orbitalmore » basis set, which is computationally less intensive. Quite intriguingly, a remarkable set of electron bridging states between QDs and TiO2 occurring via the strong bonding between the conduction bands of QDs and TiO2 is revealed. Such bridging states account for the fast adiabatic charge transfer from the QD donor to the TiO2 acceptor, and may be a general feature for strongly coupled donor/acceptor systems. All the QDs/TiO2 systems exhibit type II band alignments, with conduction band offsets that increase with the decrease in QD size. This facilitates the charge transfer from QDs donors to TiO2 acceptors and explains the dependence of the increased charge transfer rate with the decreased QD size.« less

  3. Impedance spectroscopy study of SiO2-Li2O:Nd2O3 glasses

    SciTech Connect (OSTI)

    Pereia, R.; Gozzo, C B; Guedes, I.; Boatner, Lynn A; Terezo, A J; Costa, M M

    2014-01-01

    In the present study, neodymium-doped lithium silicate glasses have been prepared by the conventional melt-quenching technique. The dielectric properties, electric modulus and electrical conductivity of SiO2-Li2O (SiLi-0Nd) and SiO2-Li2O:Nd2O3 (SiLi-1.35Nd) have been studied from 1 Hz to 1 MHz in the 333 423 K temperature range. At a given temperature and frequency, we observe that the resistivity increases while the conductivity accordingly decreases when neodymium ions are added to the glass matrix. The activation energy of two distinct regions was evaluated from the ln( dc)=f(1/T) plot and was found to be E1(T<363K)=0.61(0.66)eV and E2(T>363K)=1.26(1.09)eV for SiLi-0Nd (SiLi-1,35Nd). The dielectric constant ( Re) decreases while the dielectric loss (tan ( )) increases under Nd2O3 doping. We also observe that for both glasses, Re and tan ( ) tend to increase with increasing temperature and decrease with increasing frequency.

  4. Effects of Aging on PuO2?xH2O Particle Size in Alkaline Solution

    SciTech Connect (OSTI)

    Delegard, Calvin H.

    2013-05-01

    Between 1944 and 1989, 54.5 metric tons of the United States weapons-grade plutonium and an additional 12.9 metric tons of fuel-grade plutonium were produced and separated from irradiated fuel at the Hanford Site. Acidic high-activity wastes containing around 600 kg of plutonium were made alkaline and discharged to underground storage tanks from separations, isolation, and recycle processes to yield average plutonium concentration of about 0.003 grams per liter (or ~0.0002 wt%) in the ~200 million liter tank waste volume. The plutonium is largely associated with low-solubility metal hydroxide/oxide sludges where its low concentration and intimate mixture with neutron-absorbing elements (e.g., iron) are credited in nuclear criticality safety. However, concerns have been expressed that plutonium, in the form of plutonium hydrous oxide, PuO2?xH2O, could undergo sufficient crystal growth through dissolution and reprecipitation in the alkaline tank waste to potentially become separable from neutron absorbing constituents by settling or sedimentation. Thermodynamic considerations and laboratory studies of systems chemically analogous to tank waste show that the plutonium formed in the alkaline tank waste by precipitation through neutralization from acid solution probably entered as 24-nm PuO2?xH2O crystallite particles that, because of their low solubility and opposition from radiolytic processes, grow from that point at exceedingly slow rates, thus posing no risk of physical segregation.

  5. Modeling Excited States in TiO2 Nanoparticles: On the Accuracy of a TD-DFT Based Description

    SciTech Connect (OSTI)

    Berardo, Enrico; Hu, Hanshi; Shevlin, S. A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

    2014-03-11

    We have investigated the suitability of Time-Dependent Density Functional Theory (TD-DFT) to describe vertical low-energy excitations in naked and hydrated titanium dioxide nanoparticles through a comparison with results from Equation-of-Motion Coupled Cluster (EOM-CC) quantum chemistry methods. We demonstrate that for most TiO2 nanoparticles TD-DFT calculations with commonly used exchange-correlation (XC-)potentials (e.g. B3LYP) and EOM-CC methods give qualitatively similar results. Importantly, however, we also show that for an important subset of structures, TD-DFT gives qualitatively different results depending upon the XC-potential used and that in this case only TD-CAM-B3LYP and TD-BHLYP calculations yield results that are consistent with those obtained using EOM-CC theory. Moreover, we demonstrate that the discrepancies for such structures arise from a particular combination of defects, excitations involving which are charge-transfer excitations and hence are poorly described by XC-potentials that contain no or low fractions of Hartree-Fock like exchange. Finally, we discuss that such defects are readily healed in the presence of ubiquitously present water and that as a result the description of vertical low-energy excitations for hydrated TiO2 nanoparticles is hence non-problematic.

  6. Multifunctional Properties of Cyanate Ester Composites with SiO2 Coated Fe3O4 Fillers

    SciTech Connect (OSTI)

    Sun, Weixing; Sun, Wuzhu; Kessler, Michael R.; Bowler, Nicola; Dennis, Kevin W.; McCallum, R. William; Li, Qi; Tan, Xiaoli

    2013-02-22

    SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E cyanate ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat cyanate ester polymer is largely preserved up to 160 ?C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamic mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent magnetization in these composites.

  7. Effect of cerium incorporation into zirconia on the activity ofCu/ZrO2 for methanol synthesis via CO hydrogenation

    SciTech Connect (OSTI)

    Pokrovski, Konstantin A.; Rhodes, Michael D.; Bell, Alexis T.

    2005-08-24

    The effects of Ce incorporation into ZrO2 on the catalyticperformance of Cu/ZrO2 for the hydrogenation of CO have beeninvestigated. A Ce0.3Zr0.7O2 solid solution was synthesized by forcedhydrolysis at low pH. After calcination at 873 K, XRD and Ramanspectroscopy characterization indicated that the Ce0.3Zr0.7O2 had a t''crystal structure. 1.2 wt percent Cu/Ce0.3Zr0.7O2 exhibited H2consumption peaks at low temperature (<473 K) during H2-TPRindicating a significant fraction (~; 70 percent) of Ce4+ is reduced toCe3+. 1.2 wt percent Cu/Ce0.3Zr0.7O2 is 2.7 times more active formethanol synthesis than 1.2 wt percent Cu/m-ZrO2 at 3.0 MPa attemperatures between 473 and 523 K and exhibits a higher selectivity tomethanol. In-situ infrared spectroscopy shows that, analogous toCu/m-ZrO2, the primary surface species on Cu/Ce0.3Zr0.7O2 during COhydrogenation are formate and methoxide species. A shift in the bandposition of the bridged methoxide species indicated that some of thesegroups were bonded to both Zr4+ and Ce3+ cations. For both catalysts, therate-limiting step for methanol synthesis is the reductive elimination ofmethoxide species. The higher rate of methanol synthesis onCu/Ce0.3Zr0.7O2 relative to Cu/m-ZrO2 was primarily due to a ~; 2.4 timeshigher apparent rate constant, kapp, for methoxide hydrogenation, whichis attributed to the higher surface concentration of H atoms on theformer catalyst. The increased capacity of the Ce-containing catalyst isattributed to interactions of H atoms with Ce-O pairs present at thesurface of the oxide phase.

  8. Lithium Salts for Advanced Lithium Batteries: Li-metal, Li-O2, and Li-S

    SciTech Connect (OSTI)

    Younesi, Reza; Veith, Gabriel M; Johansson, Patrik; Edstrom, Kristina; Vegge, Tejs

    2015-01-01

    Presently lithium hexafluorophosphate (LiPF6) is the dominant Li-salt used in commercial rechargeable lithium-ion batteries (LIBs) based on a graphite anode and a 3-4 V cathode material. While LiPF6 is not the ideal Li-salt for every important electrolyte property, it has a uniquely suitable combination of properties (temperature range, passivation, conductivity, etc.) rendering it the overall best Li-salt for LIBs. However, this may not necessarily be true for other types of Li-based batteries. Indeed, next generation batteries, for example lithium-metal (Li-metal), lithium-oxygen (Li-O2), and lithium sulphur (Li-S), require a re-evaluation of Li-salts due to the different electrochemical and chemical reactions and conditions within such cells. This review explores the critical role Li-salts play in ensuring in these batteries viability.

  9. Alternation of the Pd Lattice in Nano-Sized-Pd/ZrO2 Composite during Hydrogen Absorption

    SciTech Connect (OSTI)

    Arachi, Yoshinori; Asai, Takeshi; Emura, Shuichi; Omura, Akira; Nunogaki, Masanobu; Yamaura, Shunichi; Inoue, Akihisa; Arata, Yoshiaki

    2007-02-02

    Structural analysis of high Deuterium absorbed 5 nm Pd particles in dispersed ZrO2 has been carried out using XAFS techniques. X-ray absorption spectra around the Pd K-absorption edge were observed and analyzed. The Pd-Pd bonding distance in the fcc Pd lattice was enlarged by 0.08 {approx} 0.09 A during absorption of deuterium, and it completely reverted to its original state with the release of deuterium while maintaining the crystal lattice symmetry. These changes provide evidence that deuterium locates not on the surface of the Pd particle, but rather within the Pd crystal lattice. XANES spectra clearly indicate that any change in the oxidation state of Pd are not observed, resulting in no reaction of the absorbed Deuterium atoms with Pd atoms. This paper reports the alternation of Pd lattice in nano-sized composite during hydrogen absorption. The possible models of deuterium position in the Pd lattice are also discussed.

  10. Photochemical Grafting of Organic Alkenes to Single-Crystal TiO2 Surfaces: A Mechanistic Study

    SciTech Connect (OSTI)

    Franking, Ryan A.; Kim, Heesuk; Chambers, Scott A.; Mangham, Andrew N.; Hamers, Robert J.

    2012-08-21

    The UV-induced photochemical grafting of terminal alkenes has emerged as a versatile way to form molecular layers on semiconductor surfaces. Recent studies have shown that grafting reactions can be initiated by photoelectron emission into the reactant liquid as well as by excitation across the semiconductor bandgap, but the relative importance of these two processes is expected to depend on the nature of the semiconductor and the reactant alkene and the excitation wavelength. Here we report a study of the wavelength-dependent photochemical grafting of alkenes onto single-crystal TiO2 samples. Trifluoroacetamide-protected 10-aminododec-1-ene (TFAAD), 10-N-BOC-aminodec-1-ene (t-BOC) and 1-dodecene were used as model alkenes. On rutile(110), photons with energy above the bandgap but below the expected work function are not effective at inducing grafting, while photons with energy sufficient to induce electronic transitions from the TiO2 Fermi level to electronic acceptor states of the reactant molecules induce grafting. A comparison of rutile (110), rutile(001), anatase (001), and anatase(101) samples shows slightly enhanced grafting for rutile but no difference between crystal faces for a given crystal phase. Hydroxylation of the surface increases the reaction rate by lowering the work function and thereby facilitating photoelectron ejection into the adjacent alkene. These results demonstrate that photoelectron emission is the dominant mechanism responsible for grafting when using short-wavelength (~254 nm) light and suggest that photoemission events beginning on mid-gap states may play a crucial role.

  11. Comparison of the high-pressure behavior of the cerium oxides Ce2O3 and CeO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lipp, M. J.; Jeffries, J. R.; Cynn, H.; Park Klepeis, J. -H.; Evans, W. J.; Mortensen, D. R.; Seidler, G. T.; Xiao, Y.; Chow, P.

    2016-02-09

    We studied the high-pressure behavior of Ce2O3 using angle-dispersive x-ray diffraction to 70 GPa and compared with that of CeO2. Up to the highest pressure Ce2O3 remains in the hexagonal phase (space group 164, P ¯32/m1) typical for the lanthanide sesquioxides. We did not observe a theoretically predicted phase instability for 30 GPa. The isothermal bulk modulus and its pressure derivative for the quasihydrostatic case are B0 = 111 ± 2 GPa, B'0 = 4.7 ± 0.3, and for the case without pressure-transmitting medium B0 = 104 ±4 GPa, B'0 = 6.5 ± 0.4. Starting from ambient-pressure magnetic susceptibility measurementsmore » for both oxides in highly purified form,we find that the Ce atom in Ce2O3 behaves like a trivalent Ce3+ ion (2.57μB per Ce atom) in contrast to previously published data. Since x-ray emission spectroscopy of the Lγ (4d3/2 → 2p1/2) transition is sensitive to the 4f -electron occupancy, we also followed the high-pressure dependence of this line for both oxides up to 50 GPa. We observed no change of the respective line shape, indicating that the 4f -electron configuration is stable for both materials. We posit from this data that the 4f electrons do not drive the volume collapse of CeO2 from the high-symmetry, low-pressure fluorite structure to the lower-symmetry orthorhombic phase.« less

  12. Hydrodechlorination of 1,2-Dichloroethane Catalyzedby Dendrimer-Derived Pt-Cu/SiO2 Catalysts

    SciTech Connect (OSTI)

    Xie, Hong; Howe, Jane Y; Schwartz, Viviane; Monnier, J. R.; Williams, Christopher T.; Ploehn, Harry J.

    2008-01-01

    Dendrimer-metal-nanocomposites (DMNs) were used as precursors to prepare SiO2 supported monometallic Pt, Cu and bimetallic Pt-Cu catalysts with Pt/Cu atomic ratios of 1:1 (Pt50Cu50) and 1:3 (Pt25Cu75). After impregnation of these DMNs onto the support, the catalysts were thermally treated and activated following an optimized protocol. Scanning transmission electron microscopy (STEM) shows that the metal nanoparticles in dendrimer-derived SiO2-supported catalysts are smaller and have a more narrow size distribution than those in conventional catalysts prepared using corresponding metal salts via the wet impregnation method. Slow deactivation was observed for hydrodechlorination of 1,2-dichloroethane over monometallic Cu catalysts, which showed an activity about one to two orders of magnitude lower than that of the Pt-containing catalysts. Hydrodechlorination of 1,2-dichloroethane over Pt and Pt50Cu50 catalysts mainly produces ethane and the selectivity towards ethane increases with temperature. For Pt25Cu75 catalyst, the selectivity towards ethane decreases in favor of ethylene. The overall activity decreases with increasing Cu loading in the catalysts. Activity based on surface Pt sites suggests the formation of bi-functional surfaces in Pt25Cu75 catalyst favoring C-Cl bond scission on Cu sites and hydrogenation of intermediate .CH2CH2. on Pt sites. Furthermore, kinetic analyses suggest different reaction mechanisms for hydrodechlorination of 1,2-dichloroethane over Pt and Cu-enriched surfaces in the Pt-Cu bimetallic catalysts.

  13. Hydrolysis of ZrCl4 and HfCl4: The Initial Steps in the High-Temperature Oxidation of Metal Chlorides to Produce ZrO2 and HfO2

    SciTech Connect (OSTI)

    Fang, Zongtang; Dixon, David A.

    2013-03-08

    The gas-phase hydrolysis of MCl4 (M = Zr, Hf) to produce the initial particles on the way to zirconia and hafnia nanoparticles has been studied with electronic structure theory. The potential energy surfaces, the themochemistry of the reaction species, and the reaction paths for the initial steps of MCl4 reacting with H2O have been calculated. The hydrolysis of MCl4 at higher temperatures begins with the formation of oxychlorohydroxides followed by the elimination of HCl instead of the direct production of MOCl2 and HCl or MO2 and HCl due to the substantial endothermicities associated with the formation of gas-phase MO2. The structural properties and heats of formation of the reactants and products are consistent with the available experimental results. A number of metal oxychlorides (oxychlorohydroxides) intermediate clusters have been studied to assess their role in the production of MO2 nanoparticles. The calculated clustering reaction energies of those intermediates are highly exothermic, so they could be readily formed in the hydrolysis process. These intermediate clusters can be formed exothermically from metal oxychlorohydroxides by the elimination of one HCl or H2O molecule. Our calculations show that the mechanisms leading to the formation of MO2 nanoparticles are complicated and are accompanied by the potential production of a wide range of intermediates, as found for the production of TiO2 particles from the high-temperature oxidation of TiCl4.

  14. Charging Properties of Cassiterite (alpha-SnO2) surfaces in NaCl and RbCl Ionic Media.

    SciTech Connect (OSTI)

    Rosenqvist, Jorgen K; Machesky, Michael L.; Vlcek, Lukas; Wesolowski, David J

    2009-09-01

    The acid-base properties of cassiterite (alpha-SnO2) surfaces at 10-50 degrees C were studied using potentiometric titrations of powder suspensions in aqueous NaCl and RbCl media. The proton sorption isotherms exhibited common intersection points in the pH range of 4.0-4.5 under all conditions, and the magnitude of charging was similar but not identical in NaCl and RbCl. The hydrogen bonding configuration at the oxide-water interface, obtained from classical molecular dynamics (MD) simulations, was analyzed in detail, and the results were explicitly incorporated in calculations of protonation constants for the reactive surface sites using the revised MUSIC model. The calculations indicated that the terminal SnOH2 group is more acidic than the bridging Sn2OH group, with protonation constants (log KH) of 3.60 and 5.13 at 25 degrees C, respectively. This is contrary to the situation on the isostructural alpha-TiO2 (rutile), apparently because of the difference in electronegativity between Ti and Sn. MD simulations and speciation calculations indicated considerable differences in the speciation of Na+ and Rb+, despite the similarities in overall charging. Adsorbed sodium ions are almost exclusively found in bidentate surface complexes, whereas adsorbed rubidium ions form comparable numbers of bidentate and tetradentate complexes. Also, the distribution of adsorbed Na+ between the different complexes shows a considerable dependence on the surface charge density (pH), whereas the distribution of adsorbed Rb+ is almost independent of pH. A surface complexation model (SCM) capable of accurately describing both the measured surface charge and the MD-predicted speciation of adsorbed Na+/Rb+ was formulated. According to the SCM, the deprotonated terminal group (SnOH(-0.40)) and the protonated bridging group (Sn2OH+0.36) dominate the surface speciation over the entire pH range of this study (2.7-10). The complexation of medium cations increases significantly with increasing negative surface charge, and at pH 10, roughly 40% of the terminal sites are predicted to form cation complexes, whereas anion complexation is minor throughout the studied pH range.

  15. Site-Specific Imaging of Elemental Steps in Dehydration of Diols on TiO2(110)

    SciTech Connect (OSTI)

    Acharya, Danda P.; Yoon, Yeohoon; Li, Zhenjun; Zhang, Zhenrong; Lin, Xiao; Mu, Rentao; Chen, Long; Kay, Bruce D.; Rousseau, Roger J.; Dohnalek, Zdenek

    2013-11-26

    The conversion of diols on partially reduced TiO2(110) at low coverage was studied using variable-temperature scanning tunneling microscopy, temperature programmed desorption and density functional theory calculations. We find, that below ~230 K, ethane-1,2-diol and propane-1,3-diol molecules adsorb predominantly on five-fold coordinated Ti5c atoms. The dynamic equilibrium between molecularly bound and dissociated species resulting from O-H bond scission and reformation is observed. As the diols start to diffuse on the Ti5c rows above ~230 K, they dissociate irreversibly upon encountering bridging oxygen (Ob) vacancy (VOs) defects. Two dissociation pathways, one via O-H and the other via C-O bond scission leading to identical surface intermediates, hydroxyalkoxy, Ob-(CH2)n-OH (n = 2, 3) and bridging hydroxyl, HOb, are seen. For O-H bond scission, the Ob-(CH2)n-OH is found on the position of the original VO, while for C-O scission it is found on the adjacent Ob site. Theoretical calculations suggest that the observed mixture of C-O/O-H bond breaking processes are a result of the steric factors enforced upon the diols by the second OH group that is bound to a Ti5c site. At room temperature, rich dissociation/reformation dynamics of the second, Ti5c-bound O-H leads to the formation of dioxo, Ob-(CH2)n-OTi, species. Above ~400 K, both Ob-(CH2)n-OH and Ob-(CH2)n-OTi species convert into a new intermediate, that is centered on Ob row. Combined experimental and theoretical evidence shows that this intermediate is most likely a new dioxo, Ob-(CH2)2-Ob, species. Further annealing leads to sequential C-Ob bond cleavage and alkene desorption above ~ 500 K. Simulations find that the sequential C-O bond breaking process follows a homolytic diradical pathway with the first C-O bond breaking event accompanied by a non-adiabatic electron transfer within the TiO2(110) substrate.

  16. TiO2 Nanotubes/MWCNTs Nanocomposite Photocatalysts: Synthesis, Characterization and Photocatalytic Hydrogen Evolution Under UV-Vis Light Illumination

    SciTech Connect (OSTI)

    Li, Hao-Peng; Zhang, Xiao-Yan; Cui, Xiao-Li; Lin, Yuehe

    2012-03-01

    Nanocomposite of TiO2 nanotubes (TiO2NTs) and multiwalled carbon nanotubes (MWCNTs) has been synthesized by a hydrothermal method and firstly used in photocatalytic hydrogen production. The obtained TiO2 NTs/MWCNTs composites were characterized by X-ray diffraction, transmission electron microscopy, Raman spectrum and ultraviolet-visible diffuse reflectance spectroscopy. The experimental results revealed that the MWCNTs were decorated with well dispersed anatase TiO2 nanotubes with a diameter of 8-15 nm. A slight blue shift and weak symmetry was observed for the strongest Raman peak which resulted from strain gradients originating from interface integration between TiO2 nanotubes and MWCNTs. The photocatalytic activity of the as-prepared samples was evaluated by hydrogen evolution from water splitting using Na2S and Na2SO3 as sacrificial reagents under UV-vis light irradiation. Enhanced photocatalytic activity compared with P25 has been observed for the resulted samples. The nanocomposite with optimized MWCNTs content of 1% displayed a hydrogen production rate of 161 u mol/h/g. Good photocatalytic stability of the as-synthesized samples was observed as well.

  17. Synthesis, Structure, and Electrochemical Performance of High Capacity Li2Cu0.5Ni0.5O2 Cathodes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ruther, Rose E; Zhou, Hui; Dhital, Chetan; Saravanan, Kuppan; Kercher, Andrew K.; Chen, Guoying; Huq, Ashfia; Delnick, Frank M.; Nanda, Jagjit

    2015-09-08

    Orthorhombic Li2NiO2, Li2CuO2, and solid solutions thereof have been studied as potential cathode materials for lithium-ion batteries due to their high theoretical capacity and relatively low cost. While neither endmember shows good cycling stability, the intermediate composition, Li2Cu0.5Ni0.5O2, yields reasonably high reversible capacities. A new synthetic approach and detailed characterization of this phase and the parent Li2CuO2 are presented. The cycle life of Li2Cu0.5Ni0.5O2 is shown to depend critically on the voltage window. The formation of Cu1+ at low voltage and oxygen evolution at high voltage limit the electrochemical reversibility. In situ X-ray absorption spectroscopy (XAS), in situ Raman spectroscopy,more » and gas evolution measurements are used to follow the chemical and structural changes that occur as a function of cell voltage.« less

  18. Deprotonated Water Dimers: The Building Blocks of Segmented Water Chains on Rutile RuO2(110)

    SciTech Connect (OSTI)

    Mu, Rentao; Cantu Cantu, David; Glezakou, Vassiliki Alexandra; Lyubinetsky, Igor; Rousseau, Roger J.; Dohnalek, Zdenek

    2015-10-15

    Despite the importance of RuO2 in photocatalytic water splitting and catalysis in general, the interactions of water with even its most stable (110) surface are not well-understood. In this study we employ a combination of high-resolution scanning tunneling microscopy imaging with density functional theory based ab initio molecular dynamics, and we follow the formation and binding of linear water clusters on coordinatively unsaturated ruthenium rows. We find that clusters of all sizes (dimers, trimers, tetramers, extended chains) are stabilized by donating one proton per every two water molecules to the surface bridge bonded oxygen sites, in contrast with water monomers that do not show a significant propensity for dissociation. The clusters with odd number of water molecules are less stable than the clusters with even number, and are generally not observed under thermal equilibrium. For all clusters with even numbers, the dissociated dimers represent the fundamental building blocks with strong intra-dimer hydrogen bonds and only very weak inter-dimer interactions resulting in segmented water chains.

  19. Hydrogen Reactivity on Highly-hydroxylated TiO2(110) Surfaces Prepared via Carboxylic Acid Adsorption and Photolysis

    SciTech Connect (OSTI)

    Du, Yingge; Petrik, Nikolay G.; Deskins, N. Aaron; Wang, Zhitao; Henderson, Michael A.; Kimmel, Gregory A.; Lyubinetsky, Igor

    2012-02-27

    Combined scanning tunneling microscopy, temperature-programmed desorption, photo stimulated desorption, and density functional theory studies have probed the formation and reactivity of highly-hydroxylated rutile TiO2(110) surfaces, which were prepared via a novel, photochemical route using trimethyl acetic acid (TMAA) dissociative adsorption and subsequent photolysis at 300 K. Deprotonation of TMAA molecules upon adsorption produces both surface bridging hydroxyls (OHb) and bidentate trimethyl acetate (TMA) species with a saturation coverage of near 0.5 monolayer (ML). Ultra-violet light irradiation selectively removes TMA species, producing a highly-hydroxylated surface with up to ~0.5 ML OHb coverage. At high coverages, the OHb species typically occupy second-nearest neighbor sites along the bridging oxygen row locally forming linear (21) structures of different lengths, although the surface is less ordered on a long scale. The annealing of the highly-hydroxylated surface leads to hydroxyl recombination and H2O desorption with ~100% yield, thus ruling out the diffusion of H into the bulk that has been suggested in the literature. In agreement with experimental data, theoretical results show that the recombinative H2O desorption is preferred over both H bulk diffusion and H2 desorption processes.

  20. Effect of Doping on Surface Reactivity and Conduction Mechanism in Sm-doped CeO2 Thin Films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yang, Nan; Belianinov, Alex; Strelcov, Evgheni; Tebano, Antonello; Daniele, Dr. Di Castro; Schlueter, Dr. Christoph; Lee, Dr. Tien-Lin; Baddorf, Arthur P; Wisinger, Nina; Jesse, Stephen; et al

    2014-01-01

    Scanning probe microscopy measurements show irreversible surface electrochemistry in Sm-doped CeO2 thin films, which depends on humidity, temperature and doping concentration. A systematic study by electrochemical strain microscopy (ESM) in samples with two different Sm content and in several working conditions allows disclosing the microscopic mechanism underlying the difference in water adsorption and splitting with subsequent proton liberation. We measure the behavior of the hysteresis loops by changing temperature and humidity, both in standard ESM configuration and using the first order reversal curve (FORC) method. Complementing our study with spectroscopic measurements by hard x-ray photoemission spectroscopy we find that watermore » incorporation is favored until the doping with Sm is too high to allow the presence of Ce3+. The influence of doping on the surface reactivity and conduction mechanism clearly emerges from all of our experimental results. We find that at lower Sm concentration proton conduction is prevalent, featured by lower activation energy and higher mobility. Defect concentrations determine the type of the prevalent charge carrier in a doping dependent manner.« less

  1. Multishell Au/Ag/SiO2 nanorods with tunable optical properties as single particle orientation and rotational tracking probes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chen, Kuangcai; Lin, Chia -Cheng; Vela, Javier; Fang, Ning

    2015-04-07

    In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of the hybridmore » nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.« less

  2. Ag Out-surface Diffusion In Crystalline SiC With An Effective SiO2 Diffusion Barrier

    SciTech Connect (OSTI)

    Xue, H.; Xiao, Haiyan Y.; Zhu, Zihua; Shutthanandan, V.; Snead, Lance L.; Boatner, Lynn A.; Weber, William J.; Zhang, Y.

    2015-09-01

    For applications of tristructural isotropic (TRISO) fuel particles in high temperature reactors, release of radioactive Ag isotope (110mAg) through the SiC coating layer is a safety concern. To understand the diffusion mechanism, Ag ion implantations near the surface and in the bulk were performed by utilizing different ion energies and energy-degrader foils. High temperature annealing was carried out on the as-irradiated samples to study the possible out-surface diffusion. Before and after annealing, Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) measurements were employed to obtain the elemental profiles of the implanted samples. The results suggest little migration of buried Ag in the bulk, and an out-diffusion of the implanted Ag in the near-surface region of single crystal SiC. It is also found that a SiO2 layer, which was formed during annealing, may serve as an effective barrier to reduce or prevent Ag out diffusion through the SiC coating layer.

  3. Applying ICT and IoT to Multifamily Buildings

    Broader source: Energy.gov (indexed) [DOE]

    peak demand costs Utility Approved Revenue Grade Web Accessible Data Install Wireless HVAC Load Control Empower management with 247 control Mobile alerts...

  4. Reducing Configuration Complexity with Next Gen IoT Networks

    Energy Savers [EERE]

    Custom zones Sensor per zone or fixture Local light controls Intelligent Learning SW Secure Authentication MANAGEMENT * Auto Scheduling * SW upgrades * Reports...

  5. Ti-substituted tunnel-type Na0.44MnO2 oxide as a negative electrode for aqueous sodium-ion batteries

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Yuesheng; Liu, Jue; Lee, Byungju; Qiao, Ruimin; Yang, Zhenzhong; Xu, Shuyin; Yu, Xiqian; Gu, Lin; Hu, Yong-Sheng; Yang, Wanli; et al

    2015-03-25

    The aqueous sodium-ion battery system is a safe and low-cost solution for large-scale energy storage, due to the abundance of sodium and inexpensive aqueous electrolytes. Although several positive electrode materials, e.g., Na0.44MnO2, were proposed, few negative electrode materials, e.g., activated carbon and NaTi2(PO4)3, are available. Here we show that Ti-substituted Na0.44MnO2 (Na0.44[Mn1-xTix]O2) with tunnel structure can be used as a negative electrode material for aqueous sodium-ion batteries. This material exhibits superior cyclability even without the special treatment of oxygen removal from the aqueous solution. Atomic-scale characterizations based on spherical aberration-corrected electron microscopy and ab initio calculations are utilized to accuratelymore » identify the Ti substitution sites and sodium storage mechanism. Ti substitution tunes the charge ordering property and reaction pathway, significantly smoothing the discharge/charge profiles and lowering the storage voltage. Both the fundamental understanding and practical demonstrations suggest that Na0.44[Mn1-xTix]O2 is a promising negative electrode material for aqueous sodium-ion batteries.« less

  6. Magnetic Fe3O4@TiO2 Nanoparticles-based Test Strip Immunosensing Device for Rapid Detection of Phosphorylated Butyrylcholinesterase

    SciTech Connect (OSTI)

    Ge, Xiaoxiao; Zhang, Weiying; Lin, Yuehe; Du, Dan

    2013-12-15

    An integrated magnetic nanoparticles-based test-strip immunosensing device was developed for rapid and sensitive quantification of phosphorylated butyrylcholinesterase (BChE), the biomarker of exposure to organophosphous pesticides (OP), in human plasma. In order to overcome the difficulty in scarce availability of OP-specific antibody, here magnetic Fe3O4@TiO2 nanoparticles were used and adsorbed on the test strip through a small magnet inserted in the device to capture target OP-BChE through selective binding between TiO2 and OP moiety. Further recognition was completed by horseradish peroxidase (HRP) and anti-BChE antibody (Ab) co-immobilized gold nanoparticles (GNPs). Their strong affinities among Fe3O4@TiO2, OP-BChE and HRP/Ab-GNPs were characterized by quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and square wave voltammetry (SWV) measurements. After cutting off from test strip, the resulted immunocomplex (HRP/Ab-GNPs/OP-BChE/Fe3O4@TiO2) was measured by SWV using a screen printed electrode under the test zone. Greatly enhanced sensitivity was achieved by introduction of GNPs to link enzyme and antibody at high ratio, which amplifies electrocatalytic signal significantly. Moreover, the use of test strip for fast immunoreactions reduces analytical time remarkably. Coupling with a portable electrochemical detector, the integrated device with advanced nanotechnology displays great promise for sensitive, rapid and in-filed on-site evaluation of OP poisoning.

  7. High Catalytic Activity of Au/CeOx/TiO2(110) Controlled by the Nature of the Mixed Metal Oxide at the Nanometer Level

    SciTech Connect (OSTI)

    Park, J.; Graciani, J; Evans, J; Stacchiola, D; Ma, S; Liu, P; Nambu, A; Sanz, J; Hrbek, J; et. al.

    2009-01-01

    Mixed-metal oxides play a very important role in many areas of chemistry, physics, materials science, and geochemistry. Recently, there has been a strong interest in understanding phenomena associated with the deposition of oxide nanoparticles on the surface of a second (host) oxide. Here, scanning tunneling microscopy, photoemission, and density-functional calculations are used to study the behavior of ceria nanoparticles deposited on a TiO2(110) surface. The titania substrate imposes nontypical coordination modes on the ceria nanoparticles. In the CeOx/TiO2(110) systems, the Ce cations adopt an structural geometry and an oxidation state (+3) that are quite different from those seen in bulk ceria or for ceria nanoparticles deposited on metal substrates. The increase in the stability of the Ce3+ oxidation state leads to an enhancement in the chemical and catalytic activity of the ceria nanoparticles. The codeposition of ceria and gold nanoparticles on a TiO2(110) substrate generates catalysts with an extremely high activity for the production of hydrogen through the water-gas shift reaction (H2O + CO ? H2 + CO2) or for the oxidation of carbon monoxide (2CO + O2 ? 2CO2). The enhanced stability of the Ce3+ state is an example of structural promotion in catalysis described here on the atomic level. The exploration of mixed-metal oxides at the nanometer level may open avenues for optimizing catalysts through stabilization of unconventional surface structures with special chemical activity.

  8. Conversion of CH4 into H2 at 300 C using Pd/MnO2 catalyst made with an effect of water oxidation

    SciTech Connect (OSTI)

    Koyanaka, Hideki; Takeuchi, K; Kolesnikov, Alexander I

    2014-01-01

    A novel electricity-free deposition of palladium on the surface of manganese dioxide, which has a crystal structure of ramsdellite, was studied. Using the Pd deposition, a nano-particle of Pd/MnO2 was prepared, and it was used for a catalytic performance for reforming methane into hydrogen at 300 C.

  9. Dual Phase Li4 Ti5O12TiO2 Nanowire Arrays As Integrated Anodes For High-rate Lithium-ion Batteries

    SciTech Connect (OSTI)

    Liao, Jin; Chabot, Victor; Gu, Meng; Wang, Chong M.; Xiao, Xingcheng; Chen, Zhongwei

    2014-08-19

    Lithium titanate (Li4Ti5O12) is well known as a zero strain material inherently, which provides excellent long cycle stability as a negative electrode for lithium ion batteries. However, the low specific capacity (175 mA h g?1) limits it to power batteries although the low electrical conductivity is another intrinsic issue need to be solved. In this work, we developed a facile hydrothermal and ion-exchange route to synthesize the self-supported dual-phase Li4Ti5O12TiO2 nanowire arrays to further improve its capacity as well as rate capability. The ratio of Li4Ti5O12 to TiO2 in the dual phase Li4Ti5O12TiO2 nanowire is around 2:1. The introduction of TiO2 into Li4Ti5O12 increases the specific capacity. More importantly, by interface design, it creates a dual-phase nanostructure with high grain boundary density that facilitates both electron and Li ion transport. Compared with phase-pure nanowire Li4Ti5O12 and TiO2 nanaowire arrays, the dual-phase nanowire electrode yielded superior rate capability (135.5 at 5 C, 129.4 at 10 C, 120.2 at 20 C and 115.5 mA h g?1 at 30 C). In-situ transmission electron microscope clearly shows the near zero deformation of the dual phase structure, which explains its excellent cycle stability.

  10. Preparation, characterization of Fe3O4 at TiO2 magnetic nanoparticles and their application for immunoassay of biomarker of exposure to organophosphorus pesticides

    SciTech Connect (OSTI)

    Zhang, Xiao; Wang, Hongbo; Yang, Chunming; Du, Dan; Lin, Yuehe

    2013-03-15

    Novel Fe3O4 at TiO2 magnetic nanoparticles were prepared and developed for a new nanoparticle-based immunosensor for electrochemical quantification of organophosphorylated butyrylcholinesterase (BChE) in plasma, a specific biomarker of exposure to organophosphorus (OP) agents. The Fe3O4 at TiO2 nanoparticles were synthesized by hydrolysis of tetrabutyltitanate on the surface of Fe3O4 magnetic nanospheres, and characterized by attenuated total reflection Fourier-transform infrared spectra, transmission electron microscope and X-ray diffraction. The functional Fe3O4 at TiO2 nanoparticles were performed as capture antibody to selectively enrich phosphorylated moiety instead of phosphoserine antibody in the traditional sandwich immunoassays. The secondary recognition was served by quantum dots (QDs)-tagged anti-BChE antibody (QDs-anti-BChE). With the help of a magnet, the resulting sandwich-like complex, Fe3O4 at TiO2/OP-BChE/QDs-anti-BChE, was easily isolated from sample solutions and the released cadmium ions were detected on a disposable screen-printed electrode (SPE). The binding affinities were investigated by both surface plasmon resonance (SPR) and square wave voltammetry (SWV). This method not only avoids the drawback of unavailability of commercial OP-specific antibody but also amplifies detection signal by QDs-tags together with easy separation of samples by magnetic forces. The proposed immunosensor yields a linear response over a broad OP-BChE concentrations range from 0.02 to 10 nM, with detection limit of 0.01 nM. Moreover, the disposable nanoparticle-based immunosensor has been validated with human plasma samples. It offers a new method for rapid, sensitive, selective and inexpensive screening/evaluating exposure to OP pesticides.

  11. Structure-activity relationship of Au-ZrO2 catalyst on formation of hydroxyl groups and its influence on CO oxidation

    SciTech Connect (OSTI)

    Karwacki, Christopher J; Ganesh, Panchapakesan; Kent, P. R. C.; Gordon, Wesley O; Peterson, Gregory W; Niu, Jun Jie; Gogotsi, Yury G.

    2013-01-01

    The effect of changes in morphology and surface hydroxyl species upon thermal treatment of zirconia on the oxidation activity of Au/ZrO2 catalyst was studied. We observed using transmission Fourier transform infrared (FTIR) spectroscopy progressive changes in the presence of monodentate (type I), bidentate (type II) and hydrogen bridged species (type III) for each of the thermally treated (85 to 500 C) supports consisting of bare zirconia and Au/ZrO2 catalysts. Furthermore, structural changes in zirconia were accompanied by an increase in crystal size (7 to 58 nm) and contraction of the supports porosity (SSA 532 to 7 m2 g 1) with increasing thermal treatment. Deposition of gold nanoparticles under similar preparation conditions on different thermally treated zirconia resulted in changes in the mean gold cluster size, ranging from 3.7 to 5.6 nm. Changes in the surface hydroxyl species, support structure and size of the gold centers are important parameters responsible for the observed decrease (>90%) in CO conversion activity for the Au/ZrO2 catalysts. Density functional theory calculations provide evidence of increased CO binding to Au nanoclusters in the presence of surface hydroxyls on zirconia, which increases charge transfer at the perimeter of the gold nanocluster on zirconia support. This further helps in reducing a model CO-oxidation reaction barrier in the presence of surface hydroxyls. This work demonstrates the need to understand the structure activity relationship of both the support and active particles for the design of catalytic materials.

  12. Structure-Activity Relationship of Au/ZrO2 Catalyst on Formation of Hydroxyl Groups and Its Influence on CO Oxidation

    SciTech Connect (OSTI)

    Karwacki, Christopher J; Ganesh, Panchapakesan; Gordon, Wesley O; Peterson, Gregory W; Niu, Jun Jie; Gogotsi, Yury G.

    2013-01-01

    The effect of changes in morphology and surface hydroxyl species upon thermal treatment of zirconia on the oxidation activity of Au/ZrO2 catalyst was studied. We observed using transmission fourier transform infrared (FTIR) spectroscopy progressive changes in the presence of monodentate (type I), bidentate (type II) and hydrogen bridged species (type III) for each of the thermally treated (85 to 500 C) supports consisting of bare zirconia and Au/ZrO2 catalysts. Furthermore, structural changes in zirconia were accompanied by an increase in crystal size (7 to 58 nm) and contraction of the supports porosity (SSA 532 to 7 m2/g) with increasing thermal treatment. Deposition of gold nanoparticles under similar preparation conditions on different thermally treated zirconia resulted in changes in the mean gold cluster size, ranging from 3.7 to 5.6 nm. Changes in the surface hydroxyl species, support structure and size of the gold centers are important parameters responsible for the observed decrease (> 90 %) in CO conversion activity for the Au/ZrO2 catalysts. Density functional theory calculations provide evidence of increased CO binding to Au nanoclusters in the presence of surface hydroxyls on zirconia, which increases charge transfer at the perimeter of the gold nanocluster on zirconia support. This further helps in reducing a model CO-oxidation reaction barrier in the presence of surface hydroxyls. This work demonstrates the need to understand the structure-activity relationship of both the support and active particles for the design of catalytic materials.

  13. Impact of Solvent on Photocatalytic Mechanisms: Reactions of Photodesorption Products with Ice Overlayers on the TiO2(110) Surface

    SciTech Connect (OSTI)

    Shen, Mingmin; Henderson, Michael A.

    2011-04-07

    The effects of water and methanol ice overlayers on the photodecomposition of acetone on rutile TiO2(110) were evaluated in ultrahigh vacuum (UHV) using photon stimulated desorption (PSD) and temperature programmed desorption (TPD). In the absence of ice overlayers, acetone photodecomposed on TiO2(110) at 95 K by ejection of a methyl radical into the gas phase and formation of acetate on the surface. With ice overlayers, the methyl radicals are trapped at the interface between TiO2(110) and the ice. When water ice was present, these trapped methyl radicals reacted either with each other to form ethane or with other molecules in the ice (e.g., water or displaced acetone) to form methane (CH4), ethane (CH3CH3) and other products (e.g., methanol), with all of these products trapped in the ice. The new products were free to revisit the surface or depart during desorption of the ice. When methanol ice was present, methane formation came about only from reaction of trapped methyl radicals with the methanol ice. Methane and ethane slowly leaked through methanol ice overlayers into vacuum at 95 K, but not through water ice overlayers. Different degrees of site competition between water and acetone, and between methanol and acetone led to different hydrogen abstraction pathways in the two ices. These results provide new insights into product formation routes and solution-phase radical formation mechanisms that are important in heterogeneous photocatalysis.

  14. Quantitative Phase Composition of TiO2-Coated Nanoporous-Au Monoliths by X-ray Absorption Spectroscopy and Correlations to Catalytic

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bagge-Hansen, Michael; Wichmann, Andre; Wittstock, Arne; Lee, Jonathan R. I.; Ye, Jianchao; Willey, Trevor M.; Kuntz, Joshua D.; van Buuren, Tony; Biener, Juergen; Baumer, Marcus; et al

    2014-02-03

    Porous titania/metal composite materials have many potential applications in the fields of green catalysis, energy harvesting, and storage in which both the overall morphology of the nanoporous host material and the crystallographic phase of the titania (TiO 2) guest determine the material’s performance. New insights into the structure–function relationships of these materials were obtained by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy that, for example, provides quantitative crystallographic phase composition from ultrathin, nanostructured titania films, including sensitivity to amorphous components. We demonstrate that crystallographic phase, morphology, and catalytic activity of TiO 2-functionalized nanoporous gold (np-Au) can be controlled by amore » simple annealing procedure (T < 1300 K). The material was prepared by atomic layer deposition of ~2 nm thick TiO2 on millimeter-sized samples of np-Au (40–50 nm mean ligament size) and catalytically investigated with respect to aerobic CO oxidation. Moreover, the annealing-induced changes in catalytic activity are correlated with concurrent morphology and phase changes as provided by cross-sectional scanning electron microscopy, transmission electron microscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy.« less

  15. Near-resonance enhanced O2 detection for dual-broadband pure rotational coherent anti-Stokes Raman scattering with an ultraviolet-visible setup at 266 nm

    SciTech Connect (OSTI)

    Schenk, Martin; Seeger, Thomas; Leipertz, Alfred

    2005-07-01

    Broadband and dual-broadband coherent anti-Stokes Raman scattering (CARS) are widely established tools for nonintrusive gas diagnostics. Up to now the investigations have been mainly performed for electronic nonresonant conditions of the gas species of interest. We report on the enhancement of the O2-N2 detection limit of dual-broadband pure rotational CARS by shifting the wavelength of the narrowband pump laser from the commonly used 532-266 nm. This enhancement is caused when the Schumann-Runge absorption band is approached near 176 nm. The principal concept of this experiment, i.e., covering the Raman resonance with a single- or dual-broadband combination of lasers in the visible range and moving only the narrowband probe laser near or directly into electronic resonant conditions in the UV range, should also be applicable to broadband CARS experiments to directly exploit electronic resonance effects for the purpose of single-shot concentration measurements of minority species. To quantify the enhancement in O2 sensitivity, comparative measurements at both a 266 and a 532 nm narrowband pump laser wavelength are presented, employing a 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyram (DCM) dye laser as a broadband laser source at 635 nm. An increase of approximately 13% in the ratio of the rotational CARS cross sections of O2 and N2 was obtained. The broad spectral width of the CARS excitation profile was approximately equal for both setups. Further enhancement should be achievable by shifting the narrowband pump laser closer toward 176 nm, for example, with a frequency-doubled optical parametric oscillator or an excimer laser. The principal concept of this experiment should also be applicable to broadband CARS experiments to directly exploit electronic resonance effects of the narrowband pump laser with electronic transitions of minority species for the purpose of single-shot concentration measurements of those species.

  16. Co-operativity among defect sites in AnO2+ and An4O9 (An = U, Np or Pu)

    SciTech Connect (OSTI)

    Andersson, Anders David; Lezama Pacheco, Juan; Uberuaga, Blas P; Conradson, Steven D

    2008-01-01

    Actinide dioxides derived from the AnO{sub 2} fluorite lattice are of high technological relevance due to their application in nuclear reactor fuels. Oxidation of AnO{sub 2} compounds emerges as a central theme in fuel fabrication, reactor operation, long-term storage forms for both spent fuels and surplus weapons materials, and environmental actinide migration. In this paper, we use density functional theory calculations to study the oxidation of uranium, neptunium and plutonium dioxides, AnO{sub 2} (An = U, Np or Pu), in O{sub 2} and O{sub 2}/H{sub 2}O environments. We pay particular attention to the formation of oxygen clusters (co-operativity) in AnO{sub 2+x} and how this phenomenon govern oxidation thermodynamics and the development of ordered An{sub 4}O{sub 9} compounds. The so-called split di-interstitial, which is composed of two nearest neighbor octahedral oxygen interstitials that are distorted in such a way that they dislocate one regular fluorite lattice oxygen ion to form a cluster of triangular geometry, is predicted to be the fundamental building block of the most stable cluster configurations. We also identify how the formation of oxygen defect clusters and the degree of oxidation in AnO{sub 2+x} are both governed by the characer of the An-5f to excess O-2p charger transfer, i.e. the charge transfer to the O-2p orbitals of the interstitial-like (+x) ions, and the ability of the excess O-2p orbitals to hybridize with regular fluorite lattice ions.

  17. REFERENCE NO. OF DOCUMENT BEING CONTINUED AEO CONTINUATION SHEET DE-AC27-08RV14800/039 2AG O2

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    OTHER REFERENCE NO. OF DOCUMENT BEING CONTINUED AEO CONTINUATION SHEET DE-AC27-08RV14800/039 2AG O2 NAME OF OFFEROR OR CONTRACTOR WASHINGTON RIVER PROTECTION SOLUTIONS LLC QATT I NTPIEAON ITEM NO. SUPPLIESISERVICESQUNIYNT UITPCEAOT (A) (B) (C) (D) (E) (F) Fund 01050 Appr Year 2010 Allottee 34 Reporting Entity 421301 Amount: $43,752,060.00 Account code: P&B Rocky Flats Post Retirement Benefits Fund 01050 Appr Year 2010 Allottee 34 Reporting Entity 421301 Amount: $51,480,000.00 Account,_code:

  18. Excellent Passivation and Low Reflectivity Al2O3/TiO2 Bilayer Coatings for n-Wafer Silicon Solar Cells: Preprint

    SciTech Connect (OSTI)

    Lee, B. G.; Skarp, J.; Malinen, V.; Li, S.; Choi, S.; Branz, H. M.

    2012-06-01

    A bilayer coating of Al2O3 and TiO2 is used to simultaneously achieve excellent passivation and low reflectivity on p-type silicon. This coating is targeted for achieving high efficiency n-wafer Si solar cells, where both passivation and anti-reflection (AR) are needed at the front-side p-type emitter. It could also be valuable for front-side passivation and AR of rear-emitter and interdigitated back contact p-wafer cells. We achieve high minority carrier lifetimes {approx}1 ms, as well as a nearly 2% decrease in absolute reflectivity, as compared to a standard silicon nitride AR coating.

  19. Experimental oxygen potentials of U 1-y Pr y O 2 x and thermodynamic assessment of the U-Pr-O system

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    McMurray, Jake W.; Silva, Chinthaka M.

    2015-12-09

    Thermogravimetric analysis (TGA) was used to determine the oxygen potentials of fluorite urania-praseodymia (U 1-y Pr y O 2 x) solid solutions for y = 0.10 and 0.20 between 1000 and 1500 C. A thermodynamic assessment of U-Pr-O system was performed using the CALPHAD (CALculation of PHAse Diagrams) method. The models well reproduce the TGA measurements and the computed phase relations are in good agreement with those proposed from an X-ray diffraction investigation.

  20. Experimental oxygen potentials of U1-yPryO2± x and thermodynamic assessment of the U-Pr-O system

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    McMurray, Jake W.; Silva, Chinthaka M.

    2015-12-09

    Thermogravimetric analysis (TGA) was used to determine the oxygen potentials of fluorite urania-praseodymia (U1-yPryO2± x) solid solutions for y = 0.10 and 0.20 between 1000 and 1500 °C. A thermodynamic assessment of U-Pr-O system was performed using the CALPHAD (CALculation of PHAse Diagrams) method. Furthermore, the models well reproduce the TGA measurements and the computed phase relations are in good agreement with those proposed from an X-ray diffraction investigation.

  1. Photochemical Properties, Composition, and Structure in Molecular Beam Epitaxy Grown Fe Doped and (Fe,N) Codoped Rutile TiO2(110)

    SciTech Connect (OSTI)

    Mangham, Andrew N.; Govind, Niranjan; Bowden, Mark E.; Shutthanandan, V.; Joly, Alan G.; Henderson, Michael A.; Chambers, Scott A.

    2011-08-11

    We have investigated the surface photochemical properties of Fe "doped" and (Fe,N) co-doped homoepitaxial rutile TiO2 (110) films grown by plasma assisted molecular beam epitaxy. Fe does not incorporate as an electronic dopant in the rutile lattice, but rather segregates to the film surface. However, co-deposition of Fe with N enhances the solubility of Fe, and DFT calculations suggest that co-dopant complex formation is the driving force behind the enhanced solubility. The co-doped films, in which a few atomic percent of Ti (O) are replaced with Fe (N), exhibit significant disorder compared to undoped films grown under the same conditions, presumably due to dopant-induced strain. Co-doping redshifts the rutile bandgap into the visible. However, the film surfaces are photochemically inert with respect to hole-mediated decomposition of adsorbed trimethyl acetate. The absence of photochemical activity may result from dopant-induced trap and/or recombination sites within the film. This study indicates that enhanced visible light absorptivity in TiO2 does not necessarily result in visible light initiated surface photochemistry.

  2. In-situ imaging of the nucleation and growth of epitaxial anatase TiO2(001) films on SrTiO3(001)

    SciTech Connect (OSTI)

    Du, Yingge; Kim, Dong Jun; Kaspar, Tiffany C.; Chamberlin, Sara E.; Lyubinetsky, Igor; Chambers, Scott A.

    2012-09-30

    The growth of TiO2 anatase films on Nb doped SrTiO3(001) by oxygen-assisted molecular beam epitaxy has been studied in-situ by scanning tunneling microscopy. We show that the initial growth follows the Stranski-Krastanov mode, where islands form on top of a wetting layer consisting of two monolayers (ML) of TiO2. The epitaxial islands subsequently nucleate and coalescence into large commonly-oriented crystallites. The (4x4) reconstruction observed by reflection high-energy electron diffraction (RHEED) is shown to result from the coexistence of individual (4x1) and (1x4) reconstructions present on different crystallite surfaces. The anatase grows in units of bilayers, resulting in a step height of 2 ML (~0.5 nm). This result explains the fact that the measured period of the RHEED specular-beam intensity oscillations corresponds to the time required for deposition of 2 ML. Ar ion sputtering and UHV annealing results in a transformation to coexisting (4x1) and (1x4) reconstructed terraces on individual crystallites, as commonly observed by ex-situ STM studies.

  3. Fluorocarbon assisted atomic layer etching of SiO2 and Si using cyclic Ar/C4F8 and Ar/CHF3 plasma

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-11

    The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C4F8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C4F8 injection and synchronized plasma-based low energy Ar+ ion bombardment has been established for SiO2.1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF3 as a precursor is examined and compared to C4F8. CHF3 is shown to enable selective SiO2/Si etching using a fluorocarbon (FC) film build up. Othermore » critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

  4. Local magnetism in the molecule-based metamagnet [Ru2(O2CMe)4]3[Cr(CN)6] probed with implanted muons

    SciTech Connect (OSTI)

    Lancaster, T.; Pratt, F. L.; Blundell, S. J.; Steele, Andrew J.; Baker, Peter J.; Wright, Jack D.; Fishman, Randy Scott; Miller, Joel S.

    2011-01-01

    We present a muon-spin relaxation study of local magnetism in the molecule-based metamagnet [Ru2(O2CMe)4]3[Cr(CN)6]. We observe magnetic order with TN = 33 K, although above 25 K the sublattice spins become less rigid and a degree of static magnetic disorder is observed. The comparison of measurements in applied magnetic field with simulations allows us to understand the origin of the muon response across the metamagnetic transition and to map out the phase diagram of the material. Applied hydrostatic pressures of up to 6 kbar lead to an increase in the local magnetic field along with a complex change in the internal magnetic field distribution.

  5. 15N2 formation and fast oxygen isotope exchange during pulsed 15N18O exposure of MnOx/CeO2

    SciTech Connect (OSTI)

    Kwak, Ja Hun; Szanyi, Janos

    2014-12-23

    Pulsing 15N18O onto an annealed 1% Mn16Ox/Ce16O2 catalyst resulted in very fast oxygen isotope exchange and 15N2 formation at 295 K. In the 1st 15N18O pulse, due to the presence of large number of surface oxygen defects, extensive 15N218O and 15N2 formations were observed. In subsequent pulses oxygen isotope exchange dominated as a result of highly labile oxygen in the oxide. We gratefully acknowledge the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy/Vehicle Technologies Program for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOEs Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

  6. Influence of the Electronic Structure and Optical Properties of CeO2 and UO2 for Characterization with UV-Laser Assisted Atom Probe Tomography

    SciTech Connect (OSTI)

    Billy Valderrama; H.B. Henderson; C. Yablinsky; J. Gan; T.R. Allen; M.V. Manuel

    2015-09-01

    Oxide materials are used in numerous applications such as thermal barrier coatings, nuclear fuels, and electrical conductors and sensors, all applications where nanometer-scale stoichiometric changes can affect functional properties. Atom probe tomography can be used to characterize the precise chemical distribution of individual species and spatially quantify the oxygen to metal ratio at the nanometer scale. However, atom probe analysis of oxides can be accompanied by measurement artifacts caused by laser-material interactions. In this investigation, two technologically relevant oxide materials with the same crystal structure and an anion to cation ratio of 2.00, pure cerium oxide (CeO2) and uranium oxide (UO2) are studied. It was determined that electronic structure, optical properties, heat transfer properties, and oxide stability strongly affect their evaporation behavior, thus altering their measured stoichiometry, with thermal conductance and thermodynamic stability being strong factors.

  7. LiCoO2

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs Advanced Nuclear Energy Nuclear

  8. Mathematical Analysis of High-Temperature Co-electrolysis of CO2 and O2 Production in a Closed-Loop Atmosphere Revitalization System

    SciTech Connect (OSTI)

    Michael G. McKellar; Manohar S. Sohal; Lila Mulloth; Bernadette Luna; Morgan B. Abney

    2010-03-01

    NASA has been evaluating two closed-loop atmosphere revitalization architectures based on Sabatier and Bosch carbon dioxide, CO2, reduction technologies. The CO2 and steam, H2O, co-electrolysis process is another option that NASA has investigated. Utilizing recent advances in the fuel cell technology sector, the Idaho National Laboratory, INL, has developed a CO2 and H2O co-electrolysis process to produce oxygen and syngas (carbon monoxide, CO and hydrogen, H2 mixture) for terrestrial (energy production) application. The technology is a combined process that involves steam electrolysis, CO2 electrolysis, and the reverse water gas shift (RWGS) reaction. A number of process models have been developed and analyzed to determine the theoretical power required to recover oxygen, O2, in each case. These models include the current Sabatier and Bosch technologies and combinations of those processes with high-temperature co-electrolysis. The cases of constant CO2 supply and constant O2 production were evaluated. In addition, a process model of the hydrogenation process with co-electrolysis was developed and compared. Sabatier processes require the least amount of energy input per kg of oxygen produced. If co-electrolysis replaces solid polymer electrolyte (SPE) electrolysis within the Sabatier architecture, the power requirement is reduced by over 10%, but only if heat recuperation is used. Sabatier processes, however, require external water to achieve the lower power results. Under conditions of constant incoming carbon dioxide flow, the Sabatier architectures require more power than the other architectures. The Bosch, Boudouard with co-electrolysis, and the hydrogenation with co-electrolysis processes require little or no external water. The Bosch and hydrogenation processes produce water within their reactors, which aids in reducing the power requirement for electrolysis. The Boudouard with co-electrolysis process has a higher electrolysis power requirement because carbon dioxide is split instead of water, which has a lower heat of formation. Hydrogenation with co-electrolysis offers the best overall power performance for two reasons: it requires no external water, and it produces its own water, which reduces the power requirement for co-electrolysis.

  9. Auxiliary Ligand-Dependent Assembly of Several Ni/Ni-Cd Compounds with N2O2 Donor Tetradentate Symmetrical Schiff Base Ligand

    SciTech Connect (OSTI)

    Ge, Ying Ying; Li, Guo-Bi; Fang, Hua-Cai; Zhan, Xu Lin; Gu, Zhi-Gang; Chen, Jin Hao; Sun, Feng; Cai, Yue-Peng; Thallapally, Praveen K.

    2010-09-18

    Several low-dimensional Ni/Ni-Cd complexes containing N2O2 donor tetradentate symmetrical Schiff base ligand bis(acetylacetone)ethylene-diamine (sy-H2L2), namely, [Ni(sy-L2)]2?HLa?ClO4 (2), (HLa)2?(ClO4)?(NO3) (3), [Ni(sy-L2)X]2](4,4-bipy) (where La = 5,7-dimethyl-3,6-dihydro-2H-1,4-diazepine, X = ClO4 (4), X=NO3 (5), [Ni(sy-L2)Cd(SCN)2]n (6) and [Ni(sy-L2)?Cd(N3)2]n (7) have been synthesized from [Ni(sy-L2)]2?H2O (1). Complex 2, is three component discrete assembly generated from (HLa)+ moiety bridged with [Ni(sy-L2)] unit and ClO4- anion. A solution containing complex 2 and Cd(NO3)2 results in a mixture of 1 and 3. Further re-crystallization of 1 and 3 with various auxiliary ligands, provides coordination complexes 4 7 stabilized by weak hydrogen bonds in which 6 and 7 represent the first 1D heteronuclear complexes based on symmetric acacen-base Schiff base ligand.

  10. Probing The Electrode/Electrolyte Interface in The Lithium Excess Layered Oxide Li1.2Ni0.2Mn0.6O2

    SciTech Connect (OSTI)

    Carroll, Kyler J; Qian, Danna; Fell, Chris; Calvin, Scott; Veith, Gabriel M; Chi, Miaofang; Dudney, Nancy J; Meng, Ying Shirley

    2013-01-01

    A detailed surface investigation of the lithium-excess nickel manganese layered oxide Li1.2Ni0.2Mn0.6O2 structure was carried out using x-ray photoelectron spectroscopy (XPS), total electron yield and transmission x-ray absorption spectroscopy (XAS), and electron energy loss spectroscopy (EELS) during the first two electrochemical cycles. All spectroscopy techniques consistently showed the presence of Mn4+ in the pristine material and a surprising reduction of Mn at the voltage plateau during the first charge. The Mn reduction is accompanied by the oxygen loss revealed by EELS. Upon the first discharge, the Mn at the surface never fully returns back to Mn4+. The electrode/electrolyte interface of this compound consists of the reduced Mn at the crystalline defect-spinel inner layer and an oxidized Mn species simultaneously with the presence of a superoxide species in amorphous outer layer. This proposed model signifies that oxygen vacancy formation and lithium removal result in electrolyte decomposition and superoxide formation, leading to Mn activation/dissolution and surface layer-spinel phase transformation. The results also indicate that the role of oxygen is complex and significant in contributing to the extra capacity of this class of high energy density cathode materials.

  11. Energy efficient microwave synthesis of mesoporous Ce0.5M0.5O2 (Ti, Zr, Hf) nanoparticles for low temperature CO oxidation in an ionic liquid – a comparative study

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Alammar, Tarek; Chow, Ying -Kit; Mudring, Anja -Verena

    2014-11-19

    Ce0.5M0.5O2 (M = Ti, Zr, Hf) nanoparticles have been successfully synthesized by microwave irradiation in the ionic liquid [C4mim][Tf2N] (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide). The morphology, crystallinity, and chemical composition of the obtained materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and N2–adsorption measurements. XRD and Raman spectroscopy analyses confirmed the formation of solid solutions with cubic fluorite structure. The catalytic activities of the Ce0.5M0.5O2 (M = Ti, Zr, Hf) nanoparticles were investigated in the low-temperature oxidation of CO. Ce0.5Zr0.5O2 nanospheres exhibit the best performance (100% conversion at 350 °C), followed by Ce0.5Hf0.5O2more » (55% conversion at 360 °C) and Ce0.5Ti0.5O2 (11% conversion at 350 °C). Heating the as-prepared Ce0.5Zr0.5O2 to 600 °C for extended time leads to a decrease in surface area and, as expected decreased catalytic activity. Depending on the ionic liquid the obtained Ce0.5Zr0.5O2 exhibits different morphologies, varying from nano-spheres in [C4mim][Tf2N] and [P66614][Tf2N] (P66614 = trishexyltetradecylphosphonium) to sheet-like assemblies in [C3mimOH][Tf2N] (C3mimOH = 1-(3-hydroxypropyl)-3-methylimidazolium). As a result, the microwave synthesis superiority to other heating methods like sonochemical synthesis and conventional heating was proven by comparative experiments where the catalytic activity of Ce0.5Zr0.5O2 obtained by alternate methods such as conventional heating was found to be poorer than that of the microwave-synthesised material.« less

  12. Structural changes and thermal stability of charged LiNixMnyCozO2 cathode materials studied by combined in situ time-resolved XRD and mass spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bak, Seong -Min; Hu, Enyuan; Zhou, Yongning; Yu, Xiqian; Senanayake, Sanjaya D.; Cho, Sung -Jin; Kim, Kwang -Bum; Chung, Kyung Yoon; Yang, Xiao -Qing; Nam, Kyung -Wan

    2014-11-24

    Thermal stability of charged LiNixMnyCozO2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time- resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygenmore » release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co, and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of a layered structure (R3¯m) but Co ions prefer to migrate to the 8a tetrahedral sites of a spinel structure (Fd3¯m) during the thermal decomposition. Such element-dependent cation migration plays a very important role in the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of nickel content to manganese and cobalt contents. As a result, this systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.« less

  13. Nanoscale Phase Separation, Cation Ordering, and Surface Oxygen Chemistry in Pristine Li1.2Ni0.2Mn0.6O2 for Li-Ion Batteries

    SciTech Connect (OSTI)

    Gu, Meng; Genc, Arda; Belharouak, Ilias; Wang, Dapeng; Amine, Khalil; Thevuthasan, Suntharampillai; Baer, Donald R.; Zhang, Jiguang; Browning, Nigel D.; Liu, Jun; Wang, Chong M.

    2013-05-14

    Li-rich layered material Li1.2Ni0.2Mn0.6O2 possesses high voltage and high specific capacity, which makes it an attractive candidate for the transportation industry and sustainable energy storage systems. The rechargeable capacity of the Li-ion battery is linked largely to the structural stability of the cathode materials during the charge-discharge cycles. However, the structure and cation distribution in pristine (un-cycled) Li1.2Ni0.2Mn0.6O2 have not yet been fully characterized. Using a combination of aberration-corrected scanning/transmission electron microscopy, X-ray dispersive energy spectroscopy (XEDS), electron energy loss spectroscopy (EELS), and complementary multislice image simulation, we have probed the crystal structure, cation/anion distribution, and electronic structure of Li1.2Ni0.2Mn0.6O2 nanoparticle. We discovered that the electronic structure and valence state of transition metal ions show significant variations, which have been identified to be attributed to the oxygen deficiency near the particle surfaces. Characterization of the nanoscale phase separation and cation ordering in the pristine material are critical for understanding the capacity and voltage fading of this material for battery application.

  14. The Impact of Aluminum and Iron Substitution on the Structure and Electrochemistry of Li[Ni0.4Co0.2-yMyMn0.4]O2 Materials

    SciTech Connect (OSTI)

    WIlcox, James D.; Rodriguez, Efrain E.; Doeff, Marca M.

    2009-07-23

    Li[Ni0.4Co0.2-yMyMn0.4]O2 (0<_y<_0.2) (M=Al) and Li[Ni0.4Co0.15Fe0.05Mn0.4]O2 compounds were prepared in order to investigate the effect of replacement of all or part of the cobalt on the structural and electrochemical properties. The impact of substitution on the structure has been examined by both x-ray and neutron diffraction experiments. The incorporation of aluminum has minimal effect on the anti-site defect concentration, but leads to structural changes that affect electrochemical performance. The most important effect is an opening of the lithium slab dimension upon substitution, which results in improved rate performance compared to the parent compound. In contrast, the lithium slab dimension is not affected by iron substitution and no rate enhancement effect is observed. The cycling stability of aluminum containing materials is superior to both the parent material and iron-substituted materials.

  15. Structure and Electrochemistry of LiNi1/3Co1/3-yMyMn1/3O2 (M=Ti, Al, Fe) Positive Electrode Materials

    SciTech Connect (OSTI)

    Wilcox, James; Patoux, Sebastien; Doeff, Marca

    2009-01-14

    A series of materials based on the LiNi1/3Co1/3-yMyMn1/3O2 (M = Ti,Al,Fe) system has been synthesized and examined structurally and electrochemically. It is found that the changes in electrochemical performance depend highly on the nature of the substituting atom and its effect on the crystal structure. Substitution with small amounts of Ti4+ (y = 1/12) leads to the formation of a high-capacity and high-rate positive electrode material. Iron substituted materials suffer from an increased antisite defect concentration and exhibit lower capacities and poor rate capabilities. Single-phase materials are found for LiNi1/3Co1/3-yAlyMn1/3O2 when y<_ 1/4 and all exhibit decreased capacities when cycled to 4.3 V. However, an increase in rate performance and cycle stability upon aluminum substitution is correlated with an improved lamellar structure.

  16. Eliminating Voltage Decay of Lithium-Rich Li1.14Mn0.54Ni0.14Co0.14O2 Cathodes by Controlling the Electrochemical Process

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wei, Z.; Zhu, Y.; Zhang, W.; Wang, F.; Zhang, Q.; Qiu, B.; Han, S.; Xia, Y.; Liu, Z.

    2015-03-27

    Lithium-rich material owns a particularly high capacity owing to the activation of electrochemical inactive Li2MnO3 phase. But at the same time, MnO2 phase formed after Li2MnO3 activation confronts a severe problem of converting to spinel phase, and resulting in voltage decay. To our knowledge, this phenomenon is inherent property of layered manganese oxide materials and can hardly be overcome. Based on this, unlike previous reports, herein we design a method for the first time to accelerate the phase transformation by tuning the charge upper-limit voltage at a high value, so the phase transformation process can be finished in a fewmore » cycles. Then material structure remains stable while cycling at a low upper-limit voltage. By this novel method voltage decay is eliminated significantly.« less

  17. Characterization and Electrochemical Performance of SubstitutedLiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) Cathode Materials

    SciTech Connect (OSTI)

    Wilcox, James D.; Doeff, Marca M.

    2007-11-28

    A complete series of LiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) materials have been synthesized and investigated as cathode materials for lithium ion batteries. When cycled between 2.0 and 4.3 V vs. Li/Li+ at a current density of 0.1 mA/cm2, stable capacities of ~;;160 mAh/g for y=0 to ~;;110 mAh/g for y=0.2 are achieved. Upon increasing the current density, it is found that all materials containing aluminum show reduced polarization and improved rate performance. The optimal performance at all current densities was found for the compound with y=0.05. The effect of aluminumsubstitution on the crystal structure of the host is discussed.

  18. O3-type layered transition metal oxide Na(NiCoFeTi)1/4O2 as a high rate and long cycle life cathode material for sodium ion batteries

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yue, Ji -Li; Yang, Xiao -Qing; Zhou, Yong -Ning; Yu, Xiqian; Bak, Seong -Min; Fu, Zheng -Wen

    2015-10-09

    High rate capability and long cycle life are challenging goals for the development of room temperature sodium-ion batteries. Here we report a new single phase quaternary O3-type layer-structured transition metal oxide Na(NiCoFeTi)1/4O2 synthesized by a simple solid-state reaction as a new cathode material for sodium-ion batteries. It can deliver a reversible capacity of 90.6 mA h g–1 at a rate as high as 20C. At 5C, 75.0% of the initial specific capacity can be retained after 400 cycles with a capacity-decay rate of 0.07% per cycle, demonstrating a superior long-term cyclability at high current density. X-ray diffraction and absorption characterizationmore » revealed reversible phase transformations and electronic structural changes during the Na+ deintercalation/intercalation process. Ni, Co and Fe ions contribute to charge compensation during charge and discharge. Although Ti ions do not contribute to the charge transfer, they play a very important role in stabilizing the structure during charge and discharge by suppressing the Fe migration. Additionally, Ti substitution can also smooth the charge–discharge plateaus effectively, which provides a potential advantage for the commercialization of this material for room temperature sodium-ion batteries.« less

  19. Using real-time electron microscopy to explore the effects of transition-metal composition on the local thermal stability in charged LixNiyMnzCo1-y-zO2 cathode materials

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hwang, Sooyeon; Kim, Seung Min; Bak, Seong -Min; Kim, Se Young; Cho, Byung -Won; Chung, Kyung Yoon; Lee, Jeong Yong; Stach, Eric A.; Chang, Wonyoung

    2015-05-08

    In this study, we use in-situ transmission electron microcopy (TEM) to investigate the thermal decomposition that occurs at the surface of charged LixNiyMnzCo1-y-zO2 (NMC) cathode materials of different composition (with y, z=0.8, 0.1 and 0.6, 0.2 and 0.4, 0.3), after they have been charged to their practical upper limit voltage (4.3V). By heating these materials inside the TEM, we are able to directly characterize near surface changes in both their electronic structure (using electron energy loss spectroscopy) and crystal structure and morphology (using electron diffraction and bright-field imaging). The most Ni-rich material (y, z = 0.8, 0.1) is found tomore » be thermally unstable at significantly lower temperatures than the other compositions – this is manifested by changes in both the electronic structure and the onset of phase transitions at temperatures as low as 100°C. Electron energy loss spectroscopy indicates that the thermally induced reduction of Ni ions drives these changes, and that this is exacerbated by the presence of an additional redox reaction that occurs at 4.2V in the y, z = 0.8, 0.1 material. Exploration of individual particles shows that there are substantial variations in the onset temperatures and overall extent of these changes. Of the compositions studied, the composition of y, z = 0.6, 0.2 has the optimal combination of high energy density and reasonable thermal stability. The observations herein demonstrate that real time electron microscopy provide direct insight into the changes that occur in cathode materials with temperature, allowing optimization of different alloy concentrations to maximize overall performance.« less

  20. Structural Changes and Thermal Stability of Charged LiNix Mny CozO2 Cathode Materials Studied by Combined In Situ Time-Resolved XRD and Mass Spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bak, Seong-Min; Hu, Enyuan; Zhou, Yongning; Yu, Xiqian; Senanayake, Sanjaya D.; Cho, Sung-Jin; Kim, Kwang-Bum; Chung, Kyung Yoon; Yang, Xiao-Qing; Nam, Kyung-Wan

    2014-11-24

    Thermal stability of charged LiNixMnyCozO2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time- resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygenmorerelease. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co, and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of a layered structure (R3?-m) but Co ions prefer to migrate to the 8a tetrahedral sites of a spinel structure (Fd3-m) during the thermal decomposition. Such element-dependent cation migration plays a very important role in the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of nickel content to manganese and cobalt contents. This systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.less

  1. Nature of =~SiOCrO(2)CI And (=~SiO)(2)CrO(2) Sites Prepared By Grafting CrO(2)CI(2) Onto Silica

    SciTech Connect (OSTI)

    Demmelmaier, C.A.; White, R.E.; Bokhoven, J.A.van; Scott, S.L.

    2009-05-14

    The room-temperature reaction between chromyl chloride and Sylopol 952 silicas pretreated at 200, 450, and 800 C was investigated using IR, XANES, and EXAFS spectroscopy, as well as by DFT modeling. On the silicas pretreated at 200 and 450 C, the structurally uniform sites formed by the reaction with one surface hydroxyl group are described as {triple_bond}SiOCrO{sub 2}Cl. Unreacted silanols persist on these silicas even in the presence of excess CrO{sub 2}Cl{sub 2}, and on the silica pretreated at 200 C some participate in hydrogen bonding with the grafted monochlorochromate sites. On the silica pretreated at 800 C, both {triple_bond}SiOCrO{sub 2}Cl and ({triple_bond}SiO){sub 2}CrO{sub 2} sites are formed. The latter are produced despite the absence of hydrogen-bonded hydroxyl pairs on the support. The origin of the chromate sites is proposed to be the reaction between CrO{sub 2}Cl{sub 2} and hydroxyl-substituted siloxane 2-rings. These rings are likely formed at 800 C by condensation between a pair of vicinal silanols in which one of the silanols is also a member of a geminal pair.

  2. Photoinduced electron transfer in perylene-TiO2 nanoassemblies

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    nanoassemblies Authors: Llansola-Portols, M.J., Bergkamp, J.J., Tomlin, J., Moore, T.A., Kodis, G., Moore, A.L., Cosa, G., and Palacios, R.E. Title: Photoinduced...

  3. Small, Inexpensive Combined NOx Sensor and O2 Sensor

    SciTech Connect (OSTI)

    W. N. Lawless; C. F. Clark, Jr.

    2008-09-08

    It has been successfully demonstrated in this program that a zirconia multilayer structure with rhodium-based porous electrodes performs well as an amperometric NOx sensor. The sensitivity of the sensor bodies operating at 650 to 700 C is large, with demonstrated current outputs of 14 mA at 500 ppm NOx from sensors with 30 layers. The sensor bodies are small (4.5 x 4.2 x 3.1 mm), rugged, and inexpensive. It is projected the sensor bodies will cost $5 - $10 in production. This program has built on another successful development program for an oxygen sensor based on the same principles and sponsored by DOE. This oxygen sensor is not sensitive to NOx. A significant technical hurdle has been identified and solved. It was found that the 100% Rh electrodes oxidize rapidly at the preferred operating temperatures of 650 - 700 C, and this oxidation is accompanied by a volume change which delaminates the sensors. The problem was solved by using alloys of Rh and Pt. It was found that a 10%/90% Rh/Pt alloy dropped the oxidation rate of the electrodes by orders of magnitude without degrading the NOx sensitivity of the sensors, allowing long-term stable operation at the preferred operating temperatures. Degradation in the sensor output caused by temperature cycling was identified as a change in resistance at the junction between the sensor body and the external leads attached to the sensor body. The degradation was eliminated by providing strong mechanical anchors for the wire and processing the junctions to obtain good electrical bonds. The NOx sensors also detect oxygen and therefore the fully-packaged sensor needs to be enclosed with an oxygen sensor in a small, heated zirconia chamber exposed to test gas through a diffusion plug which limits the flow of gas from the outside. Oxygen is pumped from the interior of the chamber to lower the oxygen content and the combination of measurements from the NOx and oxygen sensors yields the NOx content of the gas. Two types of electronic control units were designed and built. One control unit provides independent constant voltages to the NOx and oxygen sensors and reads the current from them (that is, detects the amount of test gas present). The second controller holds the fully-assembled sensor at the desired operating temperature and controllably pumps excess oxygen from the test chamber. While the development of the sensor body was a complete success, the development of the packaging was only partially successful. All of the basic principles were demonstrated, but the packaging was too complex to optimize the operation within the resources of the program. Thus, no fully-assembled sensors were sent to outside labs for testing of cross-sensitivities, response times, etc. Near the end of the program, Sensata Technologies of Attleboro, MA tested the sensor bodies and confirmed the CeramPhysics measurements as indicated in the following attached letter. Sensata was in the process of designing their own packaging for the sensor and performing cross-sensitivity tests when they stopped all sensor development work due to the automotive industry downturn. Recently Ceramatec Inc. of Salt Lake City has expressed an interest in testing the sensor, and other licensing opportunities are being pursued.

  4. LiCoO2 cathode charging simulation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    cathode charging simulation - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs

  5. Small, Inexpensive Combined NOx and O2 Sensor

    SciTech Connect (OSTI)

    W. Lawless; C. Clark

    2008-09-01

    It has been successfully demonstrated in this program that a zirconia multilayer structure with rhodium-based porous electrodes performs well as an amperometric NO{sub x} sensor. The sensitivity of the sensor bodies operating at 650 to 700 C is large, with demonstrated current outputs of 14 mA at 500 ppm NO{sub x} from sensors with 30 layers. The sensor bodies are small (4.5 x 4.2 x 3.1 mm), rugged, and inexpensive. It is projected the sensor bodies will cost $5-$10 in production. This program has built on another successful development program for an oxygen sensor based on the same principles and sponsored by DOE. This oxygen sensor is not sensitive to NO{sub x}. A significant technical hurdle has been identified and solved. It was found that the 100% Rh electrodes oxidize rapidly at the preferred operating temperatures of 650-700 C, and this oxidation is accompanied by a volume change which delaminates the sensors. The problem was solved by using alloys of Rh and Pt. It was found that a 10%/90% Rh/Pt alloy dropped the oxidation rate of the electrodes by orders of magnitude without degrading the NO{sub x} sensitivity of the sensors, allowing long-term stable operation at the preferred operating temperatures. Degradation in the sensor output caused by temperature cycling was identified as a change in resistance at the junction between the sensor body and the external leads attached to the sensor body. The degradation was eliminated by providing strong mechanical anchors for the wire and processing the junctions to obtain good electrical bonds. The NO{sub x} sensors also detect oxygen and therefore the fully-packaged sensor needs to be enclosed with an oxygen sensor in a small, heated zirconia chamber exposed to test gas through a diffusion plug which limits the flow of gas from the outside. Oxygen is pumped from the interior of the chamber to lower the oxygen content and the combination of measurements from the NO{sub x} and oxygen sensors yields the NO{sub x} content of the gas. Two types of electronic control units were designed and built. One control unit provides independent constant voltages to the NOx and oxygen sensors and reads the current from them (that is, detects the amount of test gas present). The second controller holds the fully-assembled sensor at the desired operating temperature and controllably pumps excess oxygen from the test chamber. While the development of the sensor body was a complete success, the development of the packaging was only partially successful. All of the basic principles were demonstrated, but the packaging was too complex to optimize the operation within the resources of the program. Thus, no fully-assembled sensors were sent to outside labs for testing of cross-sensitivities, response times, etc. Near the end of the program, Sensata Technologies of Attleboro, MA tested the sensor bodies and confirmed the CeramPhysics measurements as indicated in the following attached letter. Sensata was in the process of designing their own packaging for the sensor and performing cross-sensitivity tests when they stopped all sensor development work due to the automotive industry downturn. Recently Ceramatec Inc. of Salt Lake City has expressed an interest in testing the sensor, and other licensing opportunities are being pursued.

  6. The DMSO-Li2O2 Interface in the Rechargeable Li-O2 Battery Cathode...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Energy Frontier Research Centers (EFRC); Nanostructures for Electrical Energy Storage (NEES) Sponsoring Org: USDOE SC Office of Basic Energy Sciences (SC-22)...

  7. A Comparative Study of the Water Gas Shift Reaction Over Platinum Catalysts Supported on CeO2, TiO2 and Ce-Modified TiO2

    SciTech Connect (OSTI)

    Gonzalez, I.; Navarro, R; Wen, W; Marinkovic, N; Rodriguez, J; Rosa, F; Fierro, J

    2010-01-01

    WGS reaction has been investigated on catalysts based on platinum supported over CeO{sub 2}, TiO{sub 2} and Ce-modified TiO{sub 2}. XPS and XANES analyses performed on calcined catalysts revealed a close contact between Pt precursors and cerium species on CeO{sub 2} and Ce-modified TiO{sub 2} supports. TPR results corroborate the intimate contact between Pt and cerium entities in the Pt/Ce-TiO{sub 2} catalyst that facilitates the reducibility of the support at low temperatures while the Ce-O-Ti surface interactions established in the Ce-modified TiO{sub 2} support decreases the reduction of TiO{sub 2} at high temperature. The changes in the support reducibility leads to significant differences in the WGS activity of the studied catalysts. Pt supported on Ce-modified TiO{sub 2} support exhibits better activity than those corresponding to individual CeO{sub 2} and TiO{sub 2}-supported catalysts. Additionally, the Ce-TiO{sub 2}-supported catalyst displays better stability at reaction temperatures higher than 573 K that observed on pure TiO{sub 2}-supported counterpart. Activity measurements, when coupled with the physicochemical characterization of catalysts suggest that the modifications in the surface reducibility of the support play an essential role in the enhancement of activity and stability observed when Pt is supported on the Ce-modified TiO{sub 2} substrate.

  8. Design and Fabrication of In-Reactor Experiment to Measure Tritium Release and Speciation from LiAlO2 and LiAlO2/Zr Cermets

    Broader source: Energy.gov [DOE]

    Presentation from the 32nd Tritium Focus Group Meeting held in Germantown, Maryland on April 23-25, 2013.

  9. Preparation and Characterization of Au-ZrO2-SiO2 Nanocomposite Spheres and Their Application in Enrichment and Detection of Organophosphorus Agents

    SciTech Connect (OSTI)

    Yang, Yuqi; Tu, Haiyang; Zhang, Aidong; Du, Dan; Lin, Yuehe

    2012-03-01

    Au-ZrO{sub 2}-SiO{sub 2} nanocomposite spheres were synthesized and used as selective sorbents for the solid-phase extraction (SPE) of orananophosphorous agents. A non-enzymatic electrochemical sensor based on an Au-ZrO{sub 2}-SiO{sub 2} modified electrode was developed for selective detection of orananophosphorous pesticides (OPs). The Au-ZrO{sub 2}-SiO{sub 2} nanocomposite spheres were synthesized by hydrolysis and condensation of zirconia n-butoxide (TBOZ) on the surface of SiO{sub 2} spheres and then introduction of gold nanoparticles on the surface. Transmission electron microscope and X-ray photoelectron spectroscopy were performed to characterize the formation of the nanocomposite sphere. Fast extraction of OP was achieved by Au-ZrO{sub 2}-SiO{sub 2} modified electrode within 5 min via the specific affinity between zirconia and phosphoric group. The assay yields a broad concentration range of paraoxon-ethyl from 1.0 to 500 ng/mL{sup -1} with a detection limit 0.5 ng/mL{sup -1}. This selective and sensitive method holds great promise for the enrichment and detection of OPs.

  10. Radiation induced cavity formation and gold precipitation at the interfaces of a ZrO2/SiO2/Si heterostructure

    SciTech Connect (OSTI)

    Edmondson, Philip D; Wang, Chongmin; Zhu, Zihua; Namavar, Fereydoon; Weber, William J; Zhang, Yanwen

    2011-01-01

    Thin films nano-crystalline zirconia of ~ 300 nm thick were deposited on Si substrate, and the samples were irradiated with 2 MeV Au+ ions at temperatures of 160 and 400 K, up to fluences of 35 displacements per atom. The films were then studied using glancing incidence x-ray diffraction, Rutherford backscattering, secondary ion mass spectroscopy and transmission electron microscopy. During the irradiation, cavities were observed to form at the zirconia/silicon interface. The morphology of the cavities was found to be related to the damage state of the underlying Si substrate. Elongated cavities were observed when the substrate is heavily damaged but not amorphized; however, when the substrate is rendered amorphous, the cavities become spherical. As the ion dose increases, the cavities then act as efficient gettering sites for the Au. The concentration of oxygen within the cavities determines the order in which the cavities getter. Following complete filling of the cavities, the interface acts as the secondary gettering site for the Au. The Au precipitates are determined to be elemental in nature due to the high binding free energy for the formation of Au-silicides.

  11. Phases in ceria-zirconia binary oxide (1-x)CeO2-xZrO2 nanoparticles: the size effects

    SciTech Connect (OSTI)

    Zhang,F.; Chen, C.; Hanson, J.; Herman, I.; Chan, S.

    2006-01-01

    The phases of ceria-zirconia nanoparticles observed in air are studied as a function of particle size and composition by X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The emergence of two tetragonal phases t{prime}{prime} and t monotonically moves toward higher zirconia concentrations with decreasing particle size. A smaller particle size increases the solubility of zirconia in cubic ceria, while higher zirconia content in ceria stabilizes against coarsening. In particular, the cubic Ce{sub 1-x}Zr{sub x}O{sub 2-y} is persistent and is 8% in phase amount even at 90% zirconia with 33 nm crystal size. Neither the monoclinic phase m nor the tetragonal phase t{prime} is observed in the present nanoparticles (<40 nm). The effectiveness of these nanoparticles as oxygen source-and-sink in catalytic support is largely due to the persistence of the cubic and the t{prime}{prime} phases.

  12. Materials Data on W(ClO)2 (SG:26) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Mechanisms of Oriented Attachment of TiO2 Nanocrystals in Vacuum...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Oak Ridge National Laboratory (ORNL) Sponsoring Org: SC USDOE - Office of Science (SC) Country of Publication: United States Language: English Word Cloud More Like ...

  14. Materials Data on LiAlO2 (SG:115) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Materials Data on Zn(FeO2)2 (SG:160) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on PaO2 (SG:225) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Fabrication of 3D Core-Shell Multiwalled Carbon Nanotube@RuO2...

    Office of Scientific and Technical Information (OSTI)

    Number: SC0001160 Resource Type: Journal Article Resource Relation: Journal Name: ACS Nano; Journal Volume: 9(1); Related Information: NEES partners with University of Maryland...

  18. Materials Data on KClO2 (SG:63) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Materials Data on K2CoO2 (SG:14) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on K3CoO2 (SG:62) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Materials Data on KCuO2 (SG:63) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Materials Data on K3(NiO2)2 (SG:63) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Materials Data on K3FeO2 (SG:92) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Ultrafast visualization of crystallization and grain growth in shock-compressed SiO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gleason, A. E.; Bolme, C. A.; Lee, H. J.; Nagler, B.; Galtier, E.; Milathianaki, D.; Hawreliak, J.; Kraus, R. G.; Eggert, J. H.; Fratanduono, D. E.; et al

    2015-09-04

    Pressure- and temperature-induced phase transitions have been studied for more than a century but very little is known about the non-equilibrium processes by which the atoms rearrange. Shock compression generates a nearly instantaneous propagating high-pressure/temperature condition while in situ X-ray diffraction (XRD) probes the time-dependent atomic arrangement. Here we present in situ pump–probe XRD measurements on shock-compressed fused silica, revealing an amorphous to crystalline high-pressure stishovite phase transition. Using the size broadening of the diffraction peaks, the growth of nanocrystalline stishovite grains is resolved on the nanosecond timescale just after shock compression. At applied pressures above 18 GPa the nuclueationmore » of stishovite appears to be kinetically limited to 1.4±0.4 ns. The functional form of this grain growth suggests homogeneous nucleation and attachment as the growth mechanism. As a result, these are the first observations of crystalline grain growth in the shock front between low- and high-pressure states via XRD.« less

  5. Ostwald Ripening and Its Effect on PuO2 Particle Size in Hanford Tank Waste

    SciTech Connect (OSTI)

    Delegard, Calvin H.

    2011-09-29

    Between 1944 and 1989, the Hanford Site produced 60 percent (54.5 metric tons) of the United States weapons plutonium and produced an additional 12.9 metric tons of fuels-grade plutonium. High activity wastes, including plutonium lost from the separations processes used to isolate the plutonium, were discharged to underground storage tanks during these operations. Plutonium in the Hanford tank farms is estimated to be {approx}700 kg but may be up to {approx}1000 kg. Despite these apparent large quantities, the average plutonium concentration in the {approx}200 million liter tank waste volume is only about 0.003 grams per liter ({approx}0.0002 wt%). The plutonium is largely associated with low solubility metal hydroxide/oxide sludges where its low concentration and intimate mixture with neutron-absorbing elements (e.g., iron) are credited in nuclear criticality safety. However, concerns have been expressed that plutonium, in the form of plutonium hydrous oxide, PuO{sub 2} {center_dot} xH{sub 2}O, could undergo sufficient crystal growth through Ostwald ripening in the alkaline tank waste to potentially be separable from neutron absorbing constituents by settling or sedimentation. It was found that plutonium that entered the alkaline tank waste by precipitation through neutralization from acid solution is initially present as 2- to 3-nm (0.002- to 0.003-{mu}m) scale PuO{sub 2} {center_dot} xH{sub 2}O crystallite particles and grows from that point at exceedingly slow rates, posing no risk to physical segregation. These conclusions are reached by both general considerations of Ostwald ripening and specific observations of the behaviors of PuO{sub 2} and PuO{sub 2} {center_dot} xH{sub 2}O upon aging in alkaline solution.

  6. Atomic structure of nanometer-sized amorphous TiO2

    SciTech Connect (OSTI)

    Zhang, H.; Chen, B.; Banfield, J.F.; Waychunas, G.A.

    2008-10-15

    Amorphous titania (TiO{sub 2}) is an important precursor for synthesis of single-phase nanocrystalline anatase. We synthesized x-ray amorphous titania by hydrolysis of titanium ethoxide at the ice point. Transmission electron microscopy examination and nitrogen gas adsorption indicated the particle size of the synthesized titania is {approx} 2 nm. Synchrotron wide-angle x-ray scattering (WAXS) was used to probe the atomic correlations in this amorphous sample. Atomic pair-distribution function (PDF) derived from Fourier transform of the WAXS data was used for reverse Monte Carlo (RMC) simulations of the atomic structure of the amorphous TiO{sub 2} nanoparticles. Molecular dynamics simulations were used to generate input structures for the RMC. X-ray absorption spectroscopy (XAS) simulations were used to screen candidate structures obtained from the RMC by comparing with experimental XAS data. The structure model that best describes both the WAXS and XAS data shows that an amorphous TiO{sub 2} particle consists of a highly distorted shell and a small strained anatase-like crystalline core. The average coordination number of Ti is 5.3 and most Ti-O bonds are populated around 1.940 {angstrom}. Relative to bulk TiO{sub 2}, the reduction of the coordination number is primarily due to the truncation of the Ti-O octahedra at the amorphous nanoparticle surface and the shortening of the Ti-O bond length to the bond contraction in the distorted shell. The preexistence of the anatase-like core may be critical to the formation of single-phase nanocrystalline anatase in crystallization of amorphous TiO{sub 2} upon heating.

  7. Growth Kinetics and Modeling of Direct Oxynitride Growth with NO-O2 Gas Mixtures

    SciTech Connect (OSTI)

    Everist, Sarah; Nelson, Jerry; Sharangpani, Rahul; Smith, Paul Martin; Tay, Sing-Pin; Thakur, Randhir

    1999-05-03

    We have modeled growth kinetics of oxynitrides grown in NO-O2 gas mixtures from first principles using modified Deal-Grove equations. Retardation of oxygen diffusion through the nitrided dielectric was assumed to be the dominant growth-limiting step. The model was validated against experimentally obtained curves with good agreement. Excellent uniformity, which exceeded expected walues, was observed.

  8. Chemistry of Tantalum Clusters in Solution And on SiO(2) Supports: Analogies And Contrasts

    SciTech Connect (OSTI)

    Nemana, S.; Okamoto, N.L.; Browning, N.D.; Gates, B.C.

    2009-06-03

    Tantalum clusters have been synthesized from Ta(CH{sub 2}Ph){sub 5} on the surface of porous fumed SiO{sub 2}. When these clusters are small, incorporating, on average, several Ta atoms, their chemistry is similar to that of molecular tantalum clusters (and other early transition-metal) clusters. For example, The Ta-Ta bonds in these small supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS), IR, and UV-vis spectroscopy, being similar to those in molecular analogues. The redox reactions of the supported clusters, characterized by X-ray absorption near-edge structure, are analogous to those of early transition-metal clusters in solution. In contrast to the largest of these clusters in solution and in the solid state, those supported on SiO{sub 2} are raftlike, facilitating the substantial metal-support-oxygen bonding that is evident in the EXAFS spectra. Samples consisting of tantalum clusters on SiO{sub 2} catalyze alkane disproportionation and the conversion of methane with n-butane to give other alkanes, but catalytic properties of analogous clusters in solution have barely been explored.

  9. Materials Data on GeO2 (SG:154) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  10. Materials Data on GeO2 (SG:152) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  11. Materials Data on TiO2 (SG:15) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Materials Data on TiO2 (SG:61) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Materials Data on TiO2 (SG:227) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Materials Data on TiO2 (SG:166) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Materials Data on TiO2 (SG:60) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on TiO2 (SG:141) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Materials Data on TiO2 (SG:136) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Materials Data on TiO2 (SG:14) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Surface-structure sensitivity of CeO2 nanocrystals in photocatalysis...

    Office of Scientific and Technical Information (OSTI)

    heterogeneous (photo)catalysis. In this study, using aberration-corrected scanning transmission electron microscopy (STEM), the atomic surface structures of well-defined...

  20. Materials Data on U2Cl5O2 (SG:65) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Materials Data on U2TeO2 (SG:139) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-01-21

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Oriented conductive oxide electrodes on SiO2/Si and glass

    DOE Patents [OSTI]

    Jia, Quanxi; Arendt, Paul N.

    2001-01-01

    A thin film structure is provided including a silicon substrate with a layer of silicon dioxide on a surface thereof, and a layer of cubic oxide material deposited upon the layer of silicon dioxide by ion-beam-assisted-deposition, said layer of cubic oxide material characterized as biaxially oriented. Preferably, the cubic oxide material is yttria-stabilized zirconia. Additional thin layers of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide are deposited upon the layer of yttria-stabilized zirconia. An intermediate layer of cerium oxide is employed between the yttria-stabilized zirconia layer and the lanthanum strontium cobalt oxide layer. Also, a layer of barium strontium titanium oxide can be upon the layer of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide. Also, a method of forming such thin film structures, including a low temperature deposition of a layer of a biaxially oriented cubic oxide material upon the silicon dioxide surface of a silicon dioxide/silicon substrate is provided.

  3. Activation of a MnO2 cathode by water-stimulated Mg2+ insertion...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Energy Frontier Research Centers (EFRC); Nanostructures for Electrical Energy Storage (NEES) Sponsoring Org: USDOE SC Office of Basic Energy Sciences (SC-22)...

  4. Materials Data on SiO2 (SG:136) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. SESAME 96170, a solid-liquid equation of state for CeO2

    SciTech Connect (OSTI)

    Chisolm, Eric D.

    2014-05-02

    I describe an equation of state (EOS) for the low-pressure solid phase and liquid phase of cerium (IV) oxide, CeO2. The models and parameters used to calculate the EOS are presented in detail, and I compare with data for the full-density crystal. Hugoniot data are available only for high-porosity powders, and I discuss difficulties in comparing with such data. I have constructed SESAME 96170, an EOS for cerium (IV) oxide that includes the ambient solid and liquid phases. The EOS extends over the full standard SESAME range, but should not be used at low temperatures and high densities because of the lack of a high-pressure solid phase. I have described the models used to compute the three terms of the EOS (cold curve, nuclear, and thermal electronic), and I have given the parameters used in the models. They were determined by comparison with experimental data at P = 1 atm, including the constant-pressure specific heat, coefficient of thermal expansion, and melting and boiling points. The EOS compares well with data in its intended range of validity, but the presence of high-frequency optical modes in its phonon spectrum limits the agreement of our models with thermal data. The next step is to construct a multiphase EOS that includes the low- and high-pressure solid phases and the liquid. The DAC data from Duclos will most strongly constrain the parameters of the high-pressure solid. A remaining issue is the comparison of the crystal-density EOS with experimental Hugoniot data, which are taken at much lower initial data because the samples are porous powders. A satisfactory means of modeling porosity, allowing comparison of theory and experiment, has not yet been produced.

  6. The low energy spectrum of TeO2 bolometers: results and perspectives...

    Office of Scientific and Technical Information (OSTI)

    K. M. ; Huang, H. Z. ; Kadel, R. ; Kazkaz, K. ; Keppel, G. ; Kogler, L. ; Kolomensky, Yu. G. ; Lenz, D. ; Li, Y. L. ; Ligi, C. ; Liu, X. ; Ma, Y. G. ; Maiano, C. ; Maino, M. ;...

  7. Structure of n-alkyltrichlorosilane mono layers on Si(100)/SiO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    H. -G. Steinruck; Ocko, B.; Will, J.; Magerl, A.

    2015-10-05

    The structure of n-alkyltrichlorosilane self-assembled monolayers (SAMs) of alkyl chain lengths n = 12, 14, 18, and 22 formed on the amorphous native oxide of silicon (100) has been investigated via angstrom-resolution surface X-ray scattering techniques, with particular focus on the proliferation of lateral order along the molecules’ long axis. Grazing incidence diffraction shows that the monolayer is composed of hexagonally packed crystalline-like domains for n = 14, 18, and 22 with a lateral size of about 60 Å. However, Bragg rod analysis shows that ~12 of the CH2 units are not included in the crystalline-like domains. We assign this,more » and the limited lateral crystallites’ size, to strain induced by the size mismatch between the optimal chain–chain and headgroup–headgroup spacings. Lastly, analysis of X-ray reflectivity profiles for n = 12, 14, and 22 shows that the density profile used to successfully model n = 18 provides an excellent fit where the analysis-derived parameters provide complementary structural information to the grazing incidence results.« less

  8. Conversion of 1,2-Propylene Glycol on Rutile TiO2(110) (Journal...

    Office of Scientific and Technical Information (OSTI)

    observed product at the expense of D2O formation. Authors: Chen, Long ; Li, Zhenjun ; Smith, R. Scott ; Kay, Bruce D. ; Dohnalek, Zdenek Publication Date: 2014-07-17 OSTI...

  9. Production and properties of Si-SiO2-In Sb structures

    SciTech Connect (OSTI)

    Padalko, A.G.; Kotov, B.A.; Lazarev, V.B.; Sukharev, V.I.; Volkov, V.V.

    1985-10-01

    When MIS structures are formed by pyrolysis of silane with subsequent thermal oxidation of the film of polycrystalline silicon on sapphire and with oriented crystallization of thin layers of an indium antimonide melt on the produced structures, the highly doped silicon-silicon dioxide-InSb has a concentration of majority charge carriers of (2-5) . 10/sup 15/ cm/sup -9/ with a density of surface states of (2-8) . 10/sup 11/ ev/sup -1/ . cm/sup -2/.

  10. The low energy spectrum of TeO2 bolometers: results and perspectives...

    Office of Scientific and Technical Information (OSTI)

    Tomei, C. ; Trentalange, S. ; Ventura, G. ; Vignati, M. ; Wang, B. S. ; Wang, H. W. ; Whitten Jr., C. A. ; Wise, T. ; Woodcraft, A. ; Zanotti, L. ; Zarra, C. ; Zhu, B. X. ;...

  11. Mechanism of Methane Chemical Looping Combustion with Hematite Promoted with CeO2

    SciTech Connect (OSTI)

    Miller, Duane D.; Siriwardane, Ranjani

    2013-08-01

    Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion that produces sequestration-ready CO{sub 2} stream, reducing the energy penalty of CO{sub 2} separation from flue gases. An effective oxygen carrier for CLC will readily react with the fuel gas and will be reoxidized upon contact with oxygen. This study investigated the development of a CeO{sub 2}-promoted Fe{sub 2}O{sub 3}?hematite oxygen carrier suitable for the methane CLC process. Composition of CeO{sub 2} is between 5 and 25 wt % and is lower than what is generally used for supports in Fe{sub 2}O{sub 3} carrier preparations. The incorporation of CeO{sub 2} to the natural ore hematite strongly modifies the reduction behavior in comparison to that of CeO{sub 2} and hematite alone. Temperature-programmed reaction studies revealed that the addition of even 5 wt % CeO{sub 2} enhances the reaction capacity of the Fe{sub 2}O{sub 3} oxygen carrier by promoting the decomposition and partial oxidation of methane. Fixed-bed reactor data showed that the 5 wt % cerium oxides with 95 wt % iron oxide produce 2 times as much carbon dioxide in comparison to the sum of carbon dioxide produced when the oxides were tested separately. This effect is likely due to the reaction of CeO{sub 2} with methane forming intermediates, which are reactive for extracting oxygen from Fe{sub 2}O{sub 3} at a considerably faster rate than the rate of the direct reaction of Fe{sub 2}O{sub 3} with methane. These studies reveal that 5 wt % CeO{sub 2}/Fe{sub 2}O{sub 3} gives stable conversions over 15 reduction/oxidation cycles. Lab-scale reactor studies (pulsed mode) suggest the methane reacts initially with CeO{sub 2} lattice oxygen to form partial oxidation products (CO + H{sub 2}), which continue to react with oxygen from neighboring Fe{sub 2}O{sub 3}, leading to its complete oxidation to form CO{sub 2}. The reduced cerium oxide promotes the methane decomposition reaction to form C + H{sub 2}, which continue to react with Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} to form CO/CO{sub 2} and H{sub 2}O. This mechanism is supported by the characterization studies, which also suggest that the formation of carbonaceous intermediates may affect the reaction rate and selectivity of the oxygen carrier.

  12. FinalTechnicalReport_15U5O2I-11_RPSEA.docx

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    depth in the GOM: 1. Paired Column (PC) semi-submersible developed by Houston Offshore Engineering (HOE) 2. Deepwater Dry Tree Semi-submersible (DWDTS) developed by Kvaerner...

  13. Materials Data on S(ClO)2 (SG:43) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. SiO2 Fracture: Chemomechanics with a Machine Learning Hybrid QM/MM Scheme |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Argonne Leadership Computing Facility Crack propagation in a two-dimensional bilayer of amorphous silicon dioxide modeled with a polarizable interatomic potential Crack propagation in a two-dimensional bilayer of amorphous silicon dioxide modeled with a polarizable interatomic potential. Atoms are colored by their local potential energy on a scale normalized from dark blue, lowest energy, to yellow, highest energy. Marco Caccin and Alessandro De Vita, King's College London; James Kermode,

  15. Materials Data on LiMoO2 (SG:58) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on Na(CoO2)3 (SG:1) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Arrays of SiO(2) Substrate-Free Micromechanical Uncooled THz...

    Office of Scientific and Technical Information (OSTI)

    process flow that involved three photolithography steps and no wet etching. The noise equivalent temperature difference intrinsic to the detectors fabricated during this...

  18. Materials Data on Ti(CoO2)2 (SG:74) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Materials Data on Ni(RhO2)2 (SG:227) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on Ni(AgO)2 (SG:166) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-01-27

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Polycrystalline TiO2(B) Nanosheet Films Deposited via Langmuir...

    Office of Scientific and Technical Information (OSTI)

    Authors: Biedermann, Laura ; Kotula, Paul Gabriel ; Beechem Iii, Thomas Edwin ; Chan, Calvin ; Dylla, Anthony ; Stevenson, Keith Publication Date: 2014-03-01 OSTI Identifier: ...

  2. Materials Data on LiCuO2 (SG:166) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-04-29

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Materials Data on Li4(CuO2)3 (SG:12) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-05-16

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Materials Data on NbO2 (SG:194) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-04-29

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Materials Data on Li(FeO2)2 (SG:227) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-05-16

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Materials Data on CuO2 (SG:227) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-04-29

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Materials Data on Li(CuO2)2 (SG:227) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-04-29

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  8. Materials Data on Bi(PdO2)2 (SG:129) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-04-29

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  9. Materials Data on FeO2 (SG:141) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-04-29

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  10. Materials Data on FeO2 (SG:166) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-04-29

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  11. Materials Data on CrO2 (SG:166) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-05-16

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Effect of Spin-Orbit Coupling on the Actinide Dioxides AnO2 ...

    Office of Scientific and Technical Information (OSTI)

    E. ; Rudin, Sven P. ; Batista, Enrique R. ; McCleskey, Thomas M. ; Scott, Brian L. ; Bauer, Eve ; Joyce, John J. ; Durakiewicz, Tomasz Publication Date: 2012-10-21 OSTI...

  13. Materials Data on Ag2HgO2 (SG:96) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Materials Data on Ag2PbO2 (SG:15) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Determination of the Surface Structure of CeO2(111) by Low-Energy...

    Office of Scientific and Technical Information (OSTI)

    Resource Type: Journal Article Resource Relation: Journal Name: Journal of Chemical Physics; Related Information: Proposed for publication in Journal of Chemical Physics...

  16. TiO2 nanotube arrays for photocatalysis: Effects of crystallinity, local order, and electronic structure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Jing; Hosseinpour, Pegah M.; Luo, Si; Heiman, Don; Menon, Latika; Arena, Dario A.; Lewis, Laura H.

    2014-11-19

    To furnish insight into correlations of electronic and local structure and photoactivity, arrays of short and long TiO₂ nanotubes were synthesized by electrochemical anodization of Ti foil, followed by thermal treatment in O₂ (oxidizing), Ar (inert), and H₂ (reducing) environments. The physical and electronic structures of these nanotubes were probed with x-ray diffraction, scanning electron microscopy, and synchrotron-based x-ray absorption spectroscopy, and correlated with their photocatalytic properties. The photocatalytic activity of the nanotubes was evaluated by monitoring the degradation of methyl orange under UV-VIS light irradiation. Results show that upon annealing at 350 °C all as-anodized amorphous TiO₂ nanotube samplesmore » partially transform to the anatase structure, with variations in the degree of crystallinity and in the concentration of local defects near the nanotubes' surface (~5 nm) depending on the annealing conditions. Degradation of methyl orange was not detectable for the as-anodized TiO₂ nanotubes regardless of their length. The annealed long nanotubes demonstrated detectable catalytic activity, which was more significant with the H₂-annealed nanotubes than with the Ar- and O₂-annealed nanotube samples. This enhanced photocatalytic response of the H₂-annealed long nanotubes relative to the other samples is positively correlated with the presence of a larger concentration of lattice defects (such as Ti3+ and anticipated oxygen vacancies) and a slightly lower degree of crystallinity near the nanotube surface. These physical and electronic structural attributes impact the efficacy of visible light absorption; moreover, the increased concentration of surface defects is postulated to promote the generation of hydroxyl radicals and thus accelerate the photodegradation of the methyl orange. The information obtained from this study provides unique insight into the role of the near-surface electronic and defect structure, crystal structure, and the local chemical environment on the photocatalytic activity and may be employed for tailoring the materials' properties for photocatalysis and other energy-related applications.« less

  17. Materials Data on H9C3N3O2 (SG:19) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Tuning the Optical Properties of Mesoporous TiO2 Films by Nanoscale Engineering

    SciTech Connect (OSTI)

    Schwenzer, Birgit; Wang, Liang; Swensen, James S.; Padmaperuma, Asanga B.; Silverman, Gary; Korotkov, Roman; Gaspar, Daniel J.

    2012-07-03

    Introducing mesoscale pores into spincoated titanium dioxide films, prepared by spincoating different sol-gel precursor solutions on silicon substrates and subsequent annealing at 350 C, 400 C or 450 C, respectively, affects several optical properties of the material. The change in refractive index observed for different mesoporous anatase films directly correlates with changes in pore size, but is also in a more complex manner influenced by the film thickness and the density of pores within the films. Additionally, the band gap of the films is blueshifted by the stress the introduction of pores exerts on the inorganic matrix. The differently sized pores were templated by Pluronic{reg_sign} block copolymers in the solgel solutions and tuned by employing different annealing temperatures for the film preparation. This study focused on elucidating the effect different templating materials (F127 and P123) have on the pore size of the final mesoporous titania film, and on understanding the relation of varying polymer concentration (taking P123 as an example) in the sol-gel solution to the pore concentration and size in the resultant titania film. Titania thin film samples or corresponding titanium dioxide powders were characterized by X-ray diffraction, nitrogen adsorption, ellipsometery, UV/Vis spectrometry and other techniques to understand the interplay between mesoporosity and optical properties.

  19. Materials Data on HgO2 (SG:12) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on Na2HgO2 (SG:139) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Materials Data on BaHgO2 (SG:166) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. IR Imaging Using Arrays of SiO2 Micromechanical Detectors (Journal...

    Office of Scientific and Technical Information (OSTI)

    All the substrate material underneath the active area of each ... to a noise equivalent temperature difference (NETD) of 2.9 mK. In the present work the array was used to capture ...

  3. COAL PARTICLE FLOW PATTERNS FOR O2 ENRICHED, LOW NOx BURNERS

    SciTech Connect (OSTI)

    Jennifer L. Sinclair

    2001-09-30

    Over the past year, the hot flow studies have focused on the validation of a novel 2M near-flame combustion furnace. The 2M furnace was specifically designed to investigate burner aerodynamics and flame stability phenomena. Key accomplishments include completion of coal & oxygen mass balance calculations and derivation of emission conversion equations, upgrade of furnace equipment and flame safety systems, shakedown testing and partial completion of a parametric flame stability study. These activities are described in detail below along with a description of the 2M furnace and support systems.

  4. Coal Particle Flow Patterns for O2 Enriched, Low NOx Burners

    SciTech Connect (OSTI)

    Jennifer Sinclair Curtis

    2005-08-01

    This project involved a systematic investigation examining the effect of near-flame burner aerodynamics on standoff distance and stability of turbulent diffusion flames and the resultant NO{sub x} emissions from actual pulverized coal diffusion flames. Specifically, the scope of the project was to understand how changes in near-flame aerodynamics and transport air oxygen partial pressure can influence flame attachment and coal ignition, two properties essential to proper operation of low NO{sub x} burners. Results from this investigation utilized a new 2M tall, 0.5m in diameter combustor designed to evaluate near-flame combustion aerodynamics in terms of transport air oxygen partial pressure (Po{sub 2}), coal fines content, primary fuel and secondary air velocities, and furnace wall temperature furnish insight into fundamental processes that occur during combustion of pulverized coal in practical systems. Complementary cold flow studies were conducted in a geometrically similar chamber to analyze the detailed motion of the gas and particles using laser Doppler velocimetry. This final technical report summarizes the key findings from our investigation into coal particle flow patterns in burners. Specifically, we focused on the effects of oxygen enrichment, the effect of fines, and the effect of the nozzle velocity ratio on the resulting flow patterns. In the cold flow studies, detailed measurements using laser Doppler velocimetry (LDV) were made to determine the details of the flow. In the hot flow studies, observations of flame stability and measurements of NO{sub x} were made to determine the effects of the flow patterns on burner operation.

  5. Ion Segregation and Deliquescence of Alkali Halide Nanocrystals on SiO2

    SciTech Connect (OSTI)

    Arima, Kenta; Jiang, Peng; Lin, Deng-Sung; Verdaguer, Albert; Salmeron, Miquel

    2009-08-11

    The adsorption of water on alkali halide (KBr, KCl, KF, NaCl) nanocrystals on SiO{sub 2} and their deliquescence was investigated as a function of relative humidity (RH) from 8% to near saturation by scanning polarization force microscopy. At low humidity, water adsorption solvates ions at the surface of the crystals and increases their mobility. This results in a large increase in the dielectric constant, which is manifested in an increase in the electrostatic force and in an increase in the apparent height of the nanocrystals. Above 58% RH, the diffusion of ions leads to Ostwald ripening, where larger nanocrystals grow at the expense of the smaller ones. At the deliquescence point, droplets were formed. For KBr, KCl, and NaCl, the droplets exhibit a negative surface potential relative to the surrounding region, which is indicative of the preferential segregation of anions to the air/solution interface.

  6. Graphene oxide modified TiO2 nanotube arrays?enhanced visible light photoelectrochemical properties

    SciTech Connect (OSTI)

    Song, Peng; Zhang, Xiao-Yan; Sun, Mingxun; Cui, Xiao-Li; Lin, Yuehe

    2012-03-01

    Novel nanocomposite films based on graphene oxide (GO) and TiO{sub 2} nanotube arrays were synthesized by assembling GO on the surface of self-organized TiO{sub 2} nanotube arrays through a simple assembling method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and UV-vis diffuse reflectance spectroscopy. Photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO{sub 2} nanotube composite electrode compared with pristine TiO{sub 2} nanotube arrays. Sensitizing effect of GO on the photoelectrochemical response of TiO{sub 2} nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. Enhanced photocatalytic activity of TiO{sub 2} nanotube arrays towards degradation of methyl blue was also demonstrated after modification of GO. The results presented here demonstrate GO to be efficient for the improvement of utilization of visible light for TiO{sub 2} nanotube arrays.

  7. Thermoelectricity of Nanocomposites Containing TiO2CoO Coaxial Nanocables

    SciTech Connect (OSTI)

    Su, L.; Zhang, L.; Gana, Y.X.

    2011-04-01

    TiO{sub 2}-CoO coaxial nanocables were deposited into anodic aluminum oxide (AAO) nanoporous templates to form nanocomposite materials. Electron microscopic analysis was conducted to reveal their structures. Seebeck coefficients of the composites were measured. The highest absolute value of Seebeck coefficient is 393 {micro}V K{sup -1} for the TiO{sub 2} nanotube-filled AAO. The TiO{sub 2}-CoO coaxial nanocable-filled AAO has a lower absolute value of 300 {micro}V K{sup -1}. Both composites showed n-type behavior. The effect of Ag nanoparticles addition on the thermoelectric behavior was also examined.

  8. Large oriented arrays and continuous films of TiO2 based nanotubes.

    SciTech Connect (OSTI)

    Xu, Huifang; Liu, Jun; Voigt, James A.; Tian, Zhengrong Ryan; McKenzie, Bonnie Beth

    2003-08-01

    We report for the first time a one-step, templateless method to directly prepare large arrays of oriented TiO{sub 2}-based nanotubes and continuous films. These titania nanostructures can also be easily prepared as conformal coatings on a substrate. The nanostructured films were formed on a Ti substrate seeded with TiO{sub 2} nanoparticles. SEM and TEM results suggested that a folding mechanism of sheetlike structures was involved in the formation of the nanotubes. The oriented arrays of TiO{sub 2} nanotubes, continuous films, and coatings are expected to have potentials for applications in catalysis, filtration, sensing, photovoltaic cells, and high surface area electrodes.

  9. Pseudocapacitive Lithium-Ion Storage in Oriented Anatase TiO2 Nanotube Arrays

    SciTech Connect (OSTI)

    Zhu, K.; Wang, Q.; Kim, J. H.; Pesaran, A. A.; Frank, A. J.

    2012-06-07

    We report on the synthesis and electrochemical properties of oriented anatase TiO{sub 2} nanotube (NT) arrays as electrodes for Li-ion batteries. The TiO{sub 2} NT electrodes displayed both pseudocapacitive Li{sup +} storage associated with the NT surface and the Li{sup +} storage within the bulk material. The relative contribution of the pseudocapacitive and bulk storages depends strongly on the scan rate. While the charges are stored primarily in the bulk at low scan rates (<< 1 mV/s), the surface storage dominates the total storage capacity at higher scan rates (>1 mV/s). The storage capacity of the NT electrodes as a function of charge/discharge rates showed no dependence on the NT film thickness, suggesting that the Li{sup +} insertion/extraction processes occur homogeneously across the entire length of NT arrays. These results indicated that the electron conduction along the NT walls and the ion conduction within the electrolyte do not cause significant hindering of the charge/discharge kinetics for NT electrode architectures. As a result of the surface pseudocapacitive storage, the reversible Li{sup +} storage capacities for TiO{sub 2} NT electrodes were higher than the theoretical storage capacity for bulk anatase TiO{sub 2} materials.

  10. Applications of Tunable TiO2 Nanotubes as Nanotemplate and Photovoltaic Device

    SciTech Connect (OSTI)

    Li, Dongdong; Chang, Pai-Chun; Chien, Chung-Jen; Lu, Jia Grace

    2010-10-26

    Highly ordered anodic titanium oxide (ATO) TiO{sub 2} nanotube film has been synthesized via a typical two-step anodization method. Following a reductive doping approach, metallic materials (copper and nickel) can be efficiently electrodeposited into the nanotubes. This versatile process yields reproducible tubular structures in ATO membranes, because of the conductive nature of crystallized TiO{sub 2}, yielding promising potential for nanotemplate applications. In this paper, we present a dye-sensitized solar cell constructed by employing such ATO films. It is observed that the reductive doping treatment can also enhance the solar cells short current density and fill factor, resulting in an improved energy conversion efficiency.

  11. Interface Architecture Determined Electrocatalytic Activity of Pt on Vertically Oriented TiO2 Nanotubes

    SciTech Connect (OSTI)

    R Rettew; N Allam; F Alamgir

    2011-12-31

    The surface atomic structure and chemical state of Pt is consequential in a variety of surface-intensive devices. Herein we present the direct interrelationship between the growth scheme of Pt films, the resulting atomic and electronic structure of Pt species, and the consequent activity for methanol electro-oxidation in Pt/TiO{sub 2} nanotube hybrid electrodes. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements were performed to relate the observed electrocatalytic activity to the oxidation state and the atomic structure of the deposited Pt species. The atomic structure as well as the oxidation state of the deposited Pt was found to depend on the pretreatment of the TiO{sub 2} nanotube surfaces with electrodeposited Cu. Pt growth through Cu replacement increases Pt dispersion, and a separation of surface Pt atoms beyond a threshold distance from the TiO{sub 2} substrate renders them metallic, rather than cationic. The increased dispersion and the metallic character of Pt results in strongly enhanced electrocatalytic activity toward methanol oxidation. This study points to a general phenomenon whereby the growth scheme and the substrate-to-surface-Pt distance dictates the chemical state of the surface Pt atoms, and thereby, the performance of Pt-based surface-intensive devices.

  12. Materials Data on Y(FeO2)2 (SG:166) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Materials Data on Y(PdO2)2 (SG:88) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-03-07

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Materials Data on Y(CuO2)2 (SG:88) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Materials Data on Na2O2 (SG:189) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on H9C3N3O2 (SG:19) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Materials Data on CdO2 (SG:205) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Electrophoretic Study of the SnO2/Aqueous Solution Interface up to 260 degrees C.

    SciTech Connect (OSTI)

    Rodriguez-Santiago, V; Fedkin, Mark V.; Wesolowski, David J

    2009-07-01

    An electrophoresis cell developed in our laboratory was utilized to determine the zeta potential at the SnO{sub 2} (cassiterite)/aqueous solution (10{sup -3} mol kg{sup -1} NaCl) interface over the temperature range from 25 to 260 C. Experimental techniques and methods for the calculation of zeta potential at elevated temperature are described. From the obtained zeta potential data as a function of pH, the isoelectric points (IEPs) of SnO{sub 2} were obtained for the first time. From these IEP values, the standard thermodynamic functions were calculated for the protonation-deprotonation equilibrium at the SnO{sub 2} surface, using the 1-pK surface complexation model. It was found that the IEP values for SnO{sub 2} decrease with increasing temperature, and this behavior is compared to the predicted values by the multisite complexation (MUSIC) model and other semitheoretical treatments, and were found to be in excellent agreement.

  19. Materials Data on Cd(GaO2)2 (SG:227) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on Cd(RhO2)2 (SG:227) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Materials Data on Cd(FeO2)2 (SG:227) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Materials Data on K2CdO2 (SG:60) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Materials Data on NbO2F (SG:15) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Materials Data on TaO2F (SG:131) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Materials Data on BrO2F (SG:9) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Materials Data on In(FeO2)2 (SG:166) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-01-27

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination...

    Office of Scientific and Technical Information (OSTI)

    This content will become publicly available on September 14, 2016 Title: ... Publication Date: 2016-03-14 OSTI Identifier: 1241555 Type: Published Article Journal ...

  8. MULTIFUNCTIONAL (NOx/CO/O2) SOLID-STATE SENSORS FOR COAL COMBUSTION CONTROL

    SciTech Connect (OSTI)

    Eric D. Wachsman

    2005-05-29

    We have made great progress in both developing solid state sensors for coal combustion control and understanding the mechanism by which they operate. We have fabricated and tested numerous sensors and identified the role electrode microstructure plays in sensor response. We have developed both p-type (La{sub 2}CuO{sub 4}) and n-type (WO{sub 3}) semiconducting NO{sub x} sensing electrodes. We have demonstrated their respective sensing behavior (sensitivities and cross-sensitivities), related this behavior to their gas adsorption/desorption behavior and catalytic activity, and in so doing verified that our proposed Differential Electrode Equilibria is a more comprehensive sensing mechanism. These investigations and their results are summarized below. The composition and microstructure of the sensing electrode is the key parameters that influence the sensing performance. We investigated the effect of electrode microstructure on the NO{sub x} sensitivity and response time using a La{sub 2}CuO{sub 4}-based potentiometric sensor. Temperature dependence, cross-sensitivity and selectivities of a La{sub 2}CuO{sub 4}- and WO{sub 3}-based potentiometric NO{sub x} sensor were investigated both in N{sub 2} and in a simulated exhaust gas. We performed temperature programmed reaction (TPR) and desorption (TPD) experiments to determine the reaction and adsorption characteristics of O{sub 2}, NO{sub x}, CO, CO{sub 2}, and their mixtures on the electrodes, and related the results to sensor performance. In order to optimize the sensor electrode microstructure, powders were prepared using four different powder synthesis routes, resulting in different particle size distributions and BET surface areas. Different sintering conditions were also applied. The microstructure of electrodes, synthesized with the same composition, has a dramatic effect on both sensitivity and response time of potentiometric NO sensors, showing that large surface areas generate a porous morphology with smaller grain size, and that smaller grain size results in a sharper response and faster response time. The relative responses of the La{sub 2}CuO{sub 4}-based sensor under varied concentrations of NO, NO{sub 2}, CO, CO{sub 2} and O{sub 2} were studied. The results showed a very high sensitivity to NO, CO, and NO{sub 2} at 450 C in 3% O{sub 2}, whereas the response to O{sub 2} and CO{sub 2} gases was negligible. The NO response at 400-500 C agreed with the NO adsorption behavior. The high NO{sub 2} sensitivity at 450 C was probably related to heterogeneous catalytic activity of La{sub 2}CuO{sub 4}. The adsorption of NO was not affected by the change of O{sub 2} concentration and thus the sensor showed selective detection of NO over O{sub 2}. However, the NO sensitivity was strongly influenced by the existence of CO, H{sub 2}O, NO{sub 2}, and CO{sub 2}, as the adsorption behavior of NO was influenced by these gases. The WO{sub 3}-based sensor was able to selectively detect NO in the presence of CO{sub 2} in 3% O{sub 2} at 650 C. The NO sensitivity, however, was affected by the variation of the NO{sub 2}, CO, and H{sub 2}O concentration. No gas-solid reactions were observed using TPR in the NO-containing gas mixture, indicating that the NO response was not obtained by the conventionally accepted mixed-potential mechanism. At the same condition, the sensor had high sensitivity to {approx}10 ppm NO{sub 2} and selectivity in the presence of CO, CO{sub 2}, and H{sub 2}O, showing it to be applicable to the monitoring of NO{sub 2}. A lot different sensing properties of NO in simulated exhaust gas suggested the occurrence of gas composition change by the gas-phase and gas-solid reactions, and strong adsorption of water on the electrodes. The NO{sub 2} sensitivity in simulated exhaust gas was modified by O{sub 2} and H{sub 2}O, but not by CO and CO{sub 2}. A positive voltage response was obtained for NO{sub 2}, but negative for NO at 650 C with the n-type semiconducting WO{sub 3}-based sensor. In contrast, the opposite response direction for NO{sub x} was observed at 450 C with t

  9. MULTIFUNCTIONAL (NOx/CO/O2) SOLID-STATE SENSORS FOR COAL COMBUSTION CONTROL

    SciTech Connect (OSTI)

    Eric D. Wachsman

    2005-03-21

    Sensing properties of a La{sub 2}CuO{sub 4}- and WO{sub 3}-based potentiometric NO{sub x} sensor were investigated both in N{sub 2} and in a simulated exhaust gas. We performed temperature programmed reaction (TPR) and desorption (TPD) experiments to determine the reaction and adsorption characteristics of O{sub 2}, NO{sub x}, CO, CO{sub 2}, and their mixtures on the electrodes, and related the results to sensor performance. The relative responses of the La{sub 2}CuO{sub 4}-based sensor under varied concentrations of NO, NO{sub 2}, CO, CO{sub 2} and O{sub 2} were studied. The results showed a very high sensitivity to CO and NO{sub 2} at 450 C in 3% O{sub 2}, whereas the response to O{sub 2} and CO{sub 2} gases was negligible. The NO response at 400-500 C agreed with the NO adsorption behavior. The high NO{sub 2} sensitivity at 450 C was probably related to heterogeneous catalytic activity of La{sub 2}CuO{sub 4}. The adsorption of NO was not affected by the change of O{sub 2} concentration and thus the sensor showed selective detection of NO over O{sub 2}. However, the NO sensitivity was strongly influenced by the existence of CO, H{sub 2}O, NO{sub 2}, and CO{sub 2}, as the adsorption behavior of NO was influenced by these gases. The WO{sub 3}-based sensor was able to selectively detect NO in the presence of CO{sub 2} in 3% O{sub 2} and at 650 C. The NO sensitivity, however, was affected by the variation of the NO{sub 2}, CO, and H{sub 2}O concentration. No gas-solid reactions were observed using TPR in the NO containing gas mixture, indicating that the NO response was not obtained by the conventionally accepted mixed-potential mechanism. At the same condition the sensor had high sensitivity to {approx}10 ppm NO{sub 2} and selectivity in the presence of CO, CO{sub 2}, and H{sub 2}O, showing it to be applicable to the monitoring of NO{sub 2}. Significantly different sensing properties of NO in simulated exhaust gas suggested the occurrence of gas composition change by the gas-phase and gas-solid reactions, and strong adsorption of water on the electrodes. The NO{sub 2} sensitivity in simulated exhaust gas was modified by O{sub 2} and H{sub 2}O, but not by CO and CO{sub 2}. A positive voltage response was obtained for NO{sub 2} but negative for NO at 650 C with the n-type semiconducting WO{sub 3}-based sensor. In contrast the opposite response direction for NO{sub x} was observed at 450 C with the La{sub 2}CuO{sub 4} (p-type semiconductor).

  10. Controlling Atomic Layer Deposition of TiO2 in Aerogels through Surface Functionalization

    SciTech Connect (OSTI)

    Ghosal, S; Baumann, T F; King, J S; Kucheyev, S; Wang, Y; Worsley, M A; Biener, J; Bent, S F; Hamza, A V

    2009-03-09

    This report demonstrates a chemical functionalization method for controlling atomic layer deposition (ALD) of TiO{sub 2} in low-density nanoporous materials. Functionalization of silica aerogel with trimethylsilane is shown to strongly suppress TiO{sub 2} growth via ALD. Subsequent modification of the functionalization through selective removal of the hydrocarbon groups reactivates the aerogel towards TiO{sub 2} deposition. These results demonstrate the potential use of ALD as a selective tool for creating novel nanoporous materials. Nanoporous materials present significant technological advantage for a wide range of applications, including catalysis, energy storage and conversion, nanoelectronics to name just a few (1-4). Hence, there is considerable interest in developing synthetic pathways for the fabrication of nanoporous materials with tailored properties. Aerogels (AGs) are unique low-density, open-cell porous materials consisting of submicrometer pores and ligaments that can be used as a robust material platform for designing novel nanoporous materials. In recent years, a synthetic approach based on ALD on AG templates has emerged as a promising method for the directed growth of nanoporous materials (5-11, 18). This approach has been used successfully to prepare millimeter-sized high aspect ratio aerogels coated uniformly with zinc oxide (ZnO), tungsten (W) and alumina (Al{sub 2}O{sub 3}) (10, 11). The ALD process utilizes two sequential, self-limiting surface reactions resulting in a layer-by-layer growth mode. The self limiting nature of the surface reactions makes ALD a particularly suitable technique for uniform deposition onto high aspect ratio porous substrates. Additionally, chemical specificity of the surface reactions in ALD enables one to control the deposition process through selective functionalization of the substrate surface. In fact the functionalization of planar substrates such as silicon wafers with organosilane groups (R{sub n}SiX{sub 4-n} (n = 1-3)) has been shown to deactivate the substrate towards ZrO{sub 2}, HfO{sub 2}, ZnO, and TiO{sub 2} ALD processes (12-16). A possible mechanism for the deactivation effect is the blocking of surface functional groups, such as hydroxyl (OH) moieties, which serve as chemisorption sites for the ALD precursors and hence are essential for nucleating the deposition process. Henceforth, we shall refer to these surface functional groups as nucleation sites for the ALD process.

  11. Acidic dissolution behavior of U containing ZrO2MgO ceramics

    SciTech Connect (OSTI)

    Kiel Holliday; Nicholas Smith; Thomas Hartmann; Gary Cerefice; Ken Czerwinski

    2011-11-01

    This study explores the possibility of dissolving zirconia-magnesia inert matrix fuel containing uranium oxide as a fissile material and plutonium homolog and erbium oxide as a burnable poison with nitric and sulfuric acid as a potential first step in a reprocessing scheme. The progress of the dissolution is followed by monitoring the amount of material in solution by inductively coupled plasma-atomic emission spectroscopy, assessing the speciation of the material by time resolved laser fluorescence spectroscopy, and determining and quantifying the crystalline phases present in the remaining residue by X-ray diffraction. This study has shown a linear incongruent dissolution of the cubic zirconia phase in concentrated nitric acid under certain chemical compositions, while the magnesium oxide phase is completely soluble. In sulfuric acid uranium, erbium, and magnesium are soluble to different extents while zirconium forms a colloidal suspension that conglomerates and settles out of solution. The feasibility of the dissolution of zirconia-magnesia inert matrix fuel with nitric and sulfuric acid for reprocessing is discussed.

  12. Materials Data on ZrO2 (SG:14) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Materials Data on NaClO2 (SG:15) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Materials Data on Na2O2 (SG:189) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Materials Data on K(IrO2)4 (SG:12) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on KBiO2 (SG:15) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Materials Data on AlCuO2 (SG:194) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Materials Data on NaTlO2 (SG:166) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Materials Data on CdO2 (SG:205) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on Ba(FeO2)2 (SG:182) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Multifunctional (NOx/CO/O2) Solid-State Sensors For Coal Combustion Control

    SciTech Connect (OSTI)

    Eric D. Wachsman

    2006-12-31

    Solid-state sensors were developed for coal combustion control and the understanding of sensing mechanisms was advanced. Several semiconducting metal oxides (p-type and n-type) were used to fabricate sensor electrodes. The adsorption/desorption characteristics and catalytic activities of these materials were measured with Temperature Programmed Desorption (TPD) and Temperature Programmed Reaction (TPR) experiments. The sensitivity, selectivity, and response time of these sensors were measured for steps of NO, NO{sub 2}, CO, CO{sub 2}, O{sub 2}, and H{sub 2}O vapor in simple N{sub 2}-balanced and multi-component, simulated combustion-exhaust streams. The role of electrode microstructure and fabrication parameters on sensing performance was investigated. Proof for the proposed sensing mechanism, Differential Electrode Equilibria, was demonstrated by relating the sensing behavior (sensitivities and cross-sensitivities) of the various electrode materials to their gas adsorption/desorption behaviors and catalytic activities. A multifunctional sensor array consisting of three sensing electrodes and an integrated heater and temperature sensors was fabricated with tape-casting and screen-printing and its NO{sub x} sensing performance was measured. The multifunctional sensor demonstrated it was possible to measure NO{sub 2} independent of NO by locally heating one of the sensing electrodes. The sensor technology was licensed to Fuel FX International, Inc. Fuel FX has obtained investor funding and is developing prototype sensors as a first step in their commercialization strategy for this technology.

  2. Materials Data on VH12(ClO2)3 (SG:14) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Materials Data on P4(SeO2)3 (SG:14) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Recent Advances in Developing Platinum Monolayer Electrocatalysts for the O2 Reduction Reaction

    SciTech Connect (OSTI)

    Vukmirovic,M.B.; Sasaki, K.; Zhou, W.-P.; Li, M.; Liu, P.; Wang, J.X.; Adzic, R.R.

    2008-09-15

    For Pt, the best single-element catalyst for many reactions, the question of content and loading is exceedingly important because of its price and availability. Using platinum as a fuel-cell catalyst in automotive applications will cause an unquantifiable increase in the demand for this metal. This big obstacle for using fuel cells in electric cars must be solved by decreasing the content of Pt, which is a great challenge of electrocatalysis Over the last several years we inaugurated a new class of electrocatalysts for the oxygen reduction reaction (ORR) based on a monolayer of Pt deposited on metal or alloy carbon-supported nanoparticles. The possibility of decreasing the Pt content in the ORR catalysts down to a monolayer level has a considerable importance because this reaction requires high loadings due to its slow kinetics. The Pt-monolayer approach has several unique features and some of them are: high Pt utilization, enhanced (or decreased) activity, enhanced stability, and direct activity correlations. The synthesis of Pt monolayer (ML) electrocatalysts was facilitated by our new synthesis method which allowed us to deposit a monolayer of Pt on various metals, or alloy nanoparticles [1, 2] for the cathode electrocatalyst. In this synthesis approach Pt is laid down by the galvanically displacing a Cu monolayer, which was deposited at underpotentials in a monolayer-limited reaction on appropriate metal substrate, with Pt after immersing the electrode in a K{sub 2}PtCl{sub 4} solution.

  5. Materials Data on Sr(FeO2)2 (SG:14) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Materials Data on Sr(NiO2)4 (SG:166) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Materials Data on Sr(BiO2)2 (SG:12) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  8. Materials Data on Sr(Ag3O2)2 (SG:52) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  9. Materials Data on Sr(GaO2)2 (SG:14) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  10. Materials Data on Sr(CuO)2 (SG:141) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  11. Materials Data on Li11(NiO2)12 (SG:12) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-04-14

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Materials Data on NdO2 (SG:12) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Materials Data on Ti(FeO2)4 (SG:12) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Materials Data on SiO2 (SG:12) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Materials Data on IrO2 (SG:136) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on Ti(CoO2)2 (SG:74) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Ternary Pt/Rh/SnO2 Electrocatalysts for Oxidizing Ethanol to CO2

    SciTech Connect (OSTI)

    Adzic, R.R.; Kowal, A.; Li, M.; Shao, M.; Sasaki, K.; Vukmirovic, M.B.; Zhang, J.; Marinkovic, N.S. Liu, P.; Frenkel, A.I.

    2009-04-01

    Ethanol, with its high energy density, likely production from renewable sources and ease of storage and transportation, is almost the ideal combustible for fuel cells wherein its chemical energy can be converted directly into electrical energy. However, commercialization of direct ethanol fuel cells has been impeded by ethanol's slow, inefficient oxidation even at the best electrocatalysts. We synthesized a ternary PtRhSnO{sub 2}/C electrocatalyst by depositing platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles that is capable of oxidizing ethanol with high efficiency and holds great promise for resolving the impediments to developing practical direct ethanol fuel cells. This electrocatalyst effectively splits the C-C bond in ethanol at room temperature in acid solutions, facilitating its oxidation at low potentials to CO{sub 2}, which has not been achieved with existing catalysts. Our experiments and density functional theory calculations indicate that the electrocatalyst's activity is due to the specific property of each of its constituents, induced by their interactions. These findings help explain the high activity of Pt-Ru for methanol oxidation and the lack of it for ethanol oxidation, and point to the way to accomplishing the C-C bond splitting in other catalytic processes.

  18. Insulator to correlated metal transition in V_1-xMo_xO_2

    SciTech Connect (OSTI)

    Klimczuk, Tomasz; Ronning, Filip; Holman, Katherine; Mcqueen, Tyrel M; Williams, Anthony J; Stephens, P W; Zandbergen, Henny W; Xu, Q; Cava, Robert J

    2009-01-01

    The change from metallic to insulating states is one of the most dramatic transitions that solids undergo on cooling or chemical doping. Many materials display this transition, but only a handful have the right combination of crystal structure and physical properties to serve as model systems. VO{sub 2} is one of those materials. Using Mo as a chemical dopant in VO{sub 2}, we find unanticipated phenomenology for both the electronic and structural characteristics of the resulting insulator to metal transition. The results support a complex, previously proposed scenario involving the coexistence of both electron repulsion and electron pairing for yielding an insulator in VO{sub 2}, but not simply; many issues are raised about local versus itinerant behavior and structure-property correlations in this most iconic ofdoped correlated electron systems.

  19. DOE SSL Postings: October 13, 2015, issue

    Energy Savers [EERE]

    systems and the Internet of Things (IoT)? We know that SSL technology, by its very nature, facilitates the integration of intelligence, network interfaces, and sensors into...

  20. Fundamental Investigations of C1O2 Delignification - Final Report - 07/10/1996 - 07/09/1999

    SciTech Connect (OSTI)

    Ragauskas, Arthur J.; McDonough, T. J.

    2001-05-18

    The overall objective of this project was to develop a fundamental understanding of the mechanisms of chlorine dioxide delignification of low kappa kraft pulps and identify new methods of improving the efficiency and effectiveness of this bleaching agent. The approach adopted was to investigate the fundamental structural components of lignin that contribute to delignification reactions with chlorine dioxide. These results were then used to examine new bleaching technologies that will permit enhanced delignification while simultaneously reducing the generation of chlorinated organic compounds.

  1. Effect of surface modification by chelating agents on Fischer-Tropsch performance of Co/SiO2 catalysts

    SciTech Connect (OSTI)

    Bambal, Ashish S. [WVU; Kyugler, Edwin L. [WVU; Gardner, Todd H. [U.S. DOE; Dadyburjor, Dady B. [WVU

    2013-01-01

    The silica support of a Co-based catalyst for Fischer?Tropsch (FT) synthesis was modified by the chelating agents (CAs) nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA). After the modification, characterization of the fresh and spent catalysts shows reduced crystallite sizes, a better-dispersed Co3O4 phase on the calcined samples, and increased metal dispersions for the reduced samples. The CA-modified catalysts display higher CO conversions, product yields, reaction rates, and rate constants. The improved FT performance of CA-modified catalysts is attributed to the formation of stable complexes with Co. The superior performance of the EDTA-modified catalyst in comparison to the NTA-modified catalyst is due to the higher affinity of the former for complex formation with Co ions. 1. INTRODUCTION Fischer?Tropsch (FT) synthesis has been recognized as one of the most promising technologies for the conversion of coal, natural gas, and biomass-derived syngas into liquid fuels and chemicals.1 Limited oil reserves, energy supply security concerns, carbon credits,1 pollution abatement laws, and, most notably, uncertainty about fuel prices have increased the prospect of commercializing the FT process. Catalysts that are typically used for FT synthesis include supported Co or Fe. Cobased catalysts have the advantage of higher syngas conversion, more high-

  2. Materials Data on YbBa2(CuO2)4 (SG:65) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-03-07

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Materials Data on Ba2Li(CuO2)3 (SG:69) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-03-19

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Cycling Endurance of SONOS Non-Volatile Memory Stacks Prepared with Nitrided SiO(2)/Si(100) Intefaces

    SciTech Connect (OSTI)

    Habermehl, S.; Nasby, R.D.; Rightley, M.J.

    1999-01-11

    The effects of nitrided SiO{sub 2}/Si(100) interfaces upon cycling endurance in silicon-oxide-nitride-oxide-silicon (SONOS) non-volatile memory transistors are investigated. Analysis of MOSFET sub-threshold characteristics indicate cycling degradation to be a manifestation of interface state (D{sub it}) generation at the tunnel oxide/silicon interface. After 10{sup 6} write/erase cycles, SONOS film stacks prepared with nitrided tunnel oxides exhibit enhanced cycling endurance with {Delta}D{sub it}=3x10{sup 12} V{sup -1}cm{sup -2}, compared to {Delta}D{sub it}=2x10{sup 13} V{sup -l}cm{sup -2} for non-nitrided tunnel oxides. Additionally, if the capping oxide is formed by steam oxidation, rather than by deposition, SONOS stacks prepared with non-nitrided tunnel oxides exhibit endurance characteristics similar to stacks with nitrided tunnel oxides. From this observation it is concluded that latent nitridation of the tunnel oxidehilicon interface occurs during steam oxide cap formation.

  5. Using shaped pulses to probe energy deposition during laser-induced damage of SiO2 surfaces

    SciTech Connect (OSTI)

    Carr, C W; Cross, D; Feit, M D; Bude, J D

    2008-10-24

    Laser-induced damage initiation in silica has been shown to follow a power-law behavior with respect to pulse-length. Models based on thermal diffusion physics can successfully predict this scaling and the effect of pulse shape for pulses between about 3ns and 10ns. In this work we use sophisticated new measurement techniques and novel pulse shape experiments to test the limits of this scaling. We show that simple pulse length scaling fails for pulses below about 3ns. Furthermore, double pulse initiation experiments suggest that energy absorbed by the first pulse is lost on time scales much shorter than would be predicted for thermal diffusion. This time scale for energy loss can be strongly modulated by maintaining a small but non-zero intensity between the pulses. By producing damage with various pulse shapes and pulse trains it is demonstrated that the properties of any hypothetical thermal absorber become highly constrained.

  6. Surface and Interface Properties of 10–12 Unit Cells Thick Sputter Deposited Epitaxial CeO 2 Films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Saraf, L. V.; Wang, C. M.; Engelhard, M. H.; Nachimuthu, P.

    2008-01-01

    Ulmore » trathin and continuous epitaxial films with relaxed lattice strain can potentially maintain more of its bulk physical and chemical properties and are useful as buffer layers. We study surface, interface, and microstructural properties of ultrathin ( ∼ 10–12 unit cells thick) epitaxial ceria films grown on single crystal YSZ substrates. The out-of -plane and in-plane lattice parameters indicate relaxation in the continuous film due to misfit dislocations seen by high-resolution transmission electron microscopy (HRTEM) and substrate roughness of ∼ 1-2 unit cells, confirmed by atomic force microscopy and HRTEM. A combination of secondary sputtering, lattice mismatch, substrate roughness, and surface reduction creating secondary phase was likely the cause of surface roughness which should be reduced to a minimum level for effective use of it as buffer layers.« less

  7. Materials Data on CoH22N7(ClO2)4 (SG:2) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  8. Materials Data on K2MnH4(Cl2O)2 (SG:121) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  9. Surface and Interface Properties of 1012 Unit Cells Thick Sputter Deposited Epitaxial CeO2Films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Saraf, L. V.; Wang, C. M.; Engelhard, M. H.; Nachimuthu, P.

    2008-01-01

    Ultrathin and continuous epitaxial films with relaxed lattice strain can potentially maintain more of its bulk physical and chemical properties and are useful as buffer layers. We study surface, interface, and microstructural properties of ultrathin (?1012 unit cells thick) epitaxial ceria films grown on single crystal YSZ substrates. The out-of -plane and in-plane lattice parameters indicate relaxation in the continuous film due to misfit dislocations seen by high-resolution transmission electron microscopy (HRTEM) and substrate roughness of?1-2 unit cells, confirmed by atomic force microscopy and HRTEM. A combination of secondary sputtering, lattice mismatch, substrate roughness, and surface reduction creating secondary phasemorewas likely the cause of surface roughness which should be reduced to a minimum level for effective use of it as buffer layers.less

  10. Rhodium Catalysts in the Oxidation of CO by O2 and NO: Shape, Composition, and Hot Electron Generation

    SciTech Connect (OSTI)

    Renzas, James R.

    2010-03-08

    It is well known that the activity, selectivity, and deactivation behavior of heterogeneous catalysts are strongly affected by a wide variety of parameters, including but not limited to nanoparticle size, shape, composition, support, pretreatment conditions, oxidation state, and electronic state. Enormous effort has been expended in an attempt to understand the role of these factors on catalytic behavior, but much still remains to be discovered. In this work, we have focused on deepening the present understanding of the role of nanoparticle shape, nanoparticle composition, and hot electrons on heterogeneous catalysis in the oxidation of carbon monoxide by molecular oxygen and nitric oxide. These reactions were chosen because they are important for environmental applications, such as in the catalytic converter, and because there is a wide range of experimental and theoretical insight from previous single crystal work as well as experimental data on nanoparticles obtained using new state-of-the-art techniques that aid greatly in the interpretation of results on complex nanoparticle systems. In particular, the studies presented in this work involve three types of samples: {approx} 6.5 nm Rh nanoparticles of different shapes, {approx} 15 nm Rh1-xPdx core-shell bimetallic polyhedra nanoparticles, and Rh ultra-thin film ({approx} 5 nm) catalytic nanodiodes. The colloidal nanoparticle samples were synthesized using a co-reduction of metal salts in alcohol and supported on silicon wafers using the Langmuir-Blodgett technique. This synthetic strategy enables tremendous control of nanoparticle size, shape, and composition. Nanoparticle shape was controlled through the use of different organic polymer capping layers. Bimetallic core-shell nanoparticles were synthesized by careful choice of metal salt precursors. Rh/TiO{sub x} and Rh/GaN catalytic nanodiodes were fabricated using a variety of thin film device fabrication techniques, including reactive DC magnetron sputtering, electron beam evaporation, and rapid thermal annealing. The combination of these techniques enabled control of catalytic nanodiode morphology, geometry, and electrical properties.

  11. Materials Data on ZnH8C2N4(ClO)2 (SG:2) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Metal-to-Insulator Transition in Anatase TiO2 Thin Films Induced by Growth Rate Modulation

    SciTech Connect (OSTI)

    Tachikawa, T; Minohara, M.; Nakanishi, Y.; Hikita, Y.; Yoshita, M.; Akiyama, H.; Bell, C.; Hwang, H.Y.

    2012-06-21

    We demonstrate control of the carrier density of single phase anatase TiO{sub 2} thin films by nearly two orders of magnitude by modulating the growth kinetics during pulsed laser deposition, under fixed thermodynamic conditions. The resistivity and the intensity of the photoluminescence spectra of these TiO{sub 2} samples, both of which correlate with the number of oxygen vacancies, are shown to depend strongly on the growth rate. A quantitative model is used to explain the carrier density changes.

  13. Pressure-driven orbital reorientations and coordination-sphere reconstructions in [CuF2(H2O)2(pyz)

    SciTech Connect (OSTI)

    Prescimone, A.; Morien, C.; Allan, D.; Schlueter, J.; Tozer, S.; Manson, J. L.; Parsons, S.; Brechin, E. K.; Hill, S.

    2012-07-23

    Successive reorientations of the Jahn-Teller axes associated with the Cu{sup II} ions accompany a series of pronounced structural transitions in the title compound, as is shown by X-ray crystallography and high-frequency EPR measurements. The second transition forces a dimerization involving two thirds of the Cu{sup II} sites due to ejection of one of the water molecules from the coordination sphere

  14. Charging Properties of Cassiterite (alpha-SnO2) Surfaces in NaCl and RbCl Ionic Media.

    SciTech Connect (OSTI)

    Rosenqvist, Jorgen K; Machesky, Michael L.; Vlcek, Lukas; Wesolowski, David J

    2009-09-01

    The acid-base properties of cassiterite ({alpha}-SnO{sub 2}) surfaces at 10-50 C were studied using potentiometric titrations of powder suspensions in aqueous NaCl and RbCl media. The proton sorption isotherms exhibited common intersection points in the pH range of 4.0-4.5 under all conditions, and the magnitude of charging was similar but not identical in NaCl and RbCl. The hydrogen bonding configuration at the oxide-water interface, obtained from classical molecular dynamics (MD) simulations, was analyzed in detail, and the results were explicitly incorporated in calculations of protonation constants for the reactive surface sites using the revised MUSIC model. The calculations indicated that the terminal SnOH{sub 2} group is more acidic than the bridging Sn{sub 2}OH group, with protonation constants (log K{sub H}) of 3.60 and 5.13 at 25 C, respectively. This is contrary to the situation on the isostructural {alpha}-TiO{sub 2} (rutile), apparently because of the difference in electronegativity between Ti and Sn. MD simulations and speciation calculations indicated considerable differences in the speciation of Na{sup +} and Rb{sup +}, despite the similarities in overall charging. Adsorbed sodium ions are almost exclusively found in bidentate surface complexes, whereas adsorbed rubidium ions form comparable numbers of bidentate and tetradentate complexes. Also, the distribution of adsorbed Na{sup +} between the different complexes shows a considerable dependence on the surface charge density (pH), whereas the distribution of adsorbed Rb{sup +} is almost independent of pH. A surface complexation model (SCM) capable of accurately describing both the measured surface charge and the MD-predicted speciation of adsorbed Na{sup +}/Rb{sup +} was formulated. According to the SCM, the deprotonated terminal group (SnOH{sup -0.40}) and the protonated bridging group (Sn{sub 2}OH{sup +0.36}) dominate the surface speciation over the entire pH range of this study (2.7-10). The complexation of medium cations increases significantly with increasing negative surface charge, and at pH 10, roughly 40% of the terminal sites are predicted to form cation complexes, whereas anion complexation is minor throughout the studied pH range.

  15. Synthesis and electronic structure of low-density monoliths of nanoporous nanocrystalline anatase TiO2

    SciTech Connect (OSTI)

    Kucheyev, S O; Baumann, T F; Wang, Y M; van Buuren, T; Satcher, J H

    2004-08-13

    Monolithic nanocrystalline anatase titania aerogels are synthesized by the epoxide sol-gel method followed by thermal annealing at 550 C. These aerogels are formed by {approx}10-20 nm size anatase nanoparticles which are randomly oriented and interconnected into an open-cell solid network. Aerogel monoliths have an apparent density of {approx}6% and a surface area of {approx} 100 m{sup 2} g{sup -1}. High-resolution transmission electron microscopy and soft x-ray absorption near-edge structure spectroscopy reveal good crystallinity of the anatase nanoparticles forming the aerogel skeleton.

  16. Ethanol Oxidation on the Ternary PtRhSnO2/C Electrocatalysts with Varied Pt:Rh:Sn ratios

    SciTech Connect (OSTI)

    Adzic, R.R.; Li, M.; Kowal, A.; Sasaki, K.; Marinkovic, N.; Su, D.; Korach, E.; Liu, P.

    2010-05-30

    Ternary Pt-Rh-SnO{sub 2}/C electrocatalysts with the atomic ratio Pt:Rh:Sn = 3:1:x, where x varies from 2 to 6, were synthesized using the modified polyol method followed by thermal treatment. Several techniques used to characterize these electrocatalysts showed they were composed of homogeneous PtRh alloy and SnO{sub 2}, having all three constituents coexisting in single nanoparticles with the average particle size around 1.4 nm and a narrow size distribution. While all the electrocatalysts investigated exhibited high catalytic activity for ethanol oxidation, the most active one had the composition with the Pt:Rh:Sn = 3:1:4 atomic ratio. These ternary-electrocatalysts effectively split the C-C bond in ethanol at room temperature in acidic solutions, which is verified using the in situ IRRAS technique.

  17. Anomalous grain growth in the surface region of a nanocrystalline CeO2 film under low-temperature heavy ion irradiation

    SciTech Connect (OSTI)

    Edmondson, Philip D.; Zhang, Yanwen; Moll, Sandra J.; Varga, Tamas; Namavar, Fereydoon; Weber, William J.

    2012-06-15

    Grain growth and phase stability of nanocrystalline ceria are investigated under ion irradiation at different temperatures. Irradiations at temperatures of 300 and 400 K result in uniform grain growth throughout the film. Anomalous grain growth is observed in thin films of nanocrystalline ceria under 3 MeV Au+ irradiation at 160 K. At this low temperature, significant grain growth is observed within 100 nm from the surface, no obvious growth is detected in the rest of the films. While the grain growth is attributed to a defect-stimulated mechanism at room temperature and above, a defect diffusion-limited mechanism is significant at low temperature with the primary defect responsible being the oxygen vacancy. The nanocrystalline grains remain in the cubic phase regardless of defect kinetics.

  18. Structural and Mechanistic Analysis through Electronic Spectra: Aqueous Hyponitrite Radical (N2O2-) and Nitrosyl Hyponitrite Anion (N3O3-)

    SciTech Connect (OSTI)

    Valiev, Marat; Lymar, Sergei V.

    2011-11-03

    Aqueous hyponitrite radical (N{sub 2}O{sub 2}{sup -}) and nitrosyl hyponitrite anion (N{sub 3}O{sub 3}{sup -}) species are important intermediates in the reductive chemistry of NO. The structures and absorption spectra of various hydrated isomers of these compounds were investigated in this work using high-level quantum mechanical calculations combined with the explicit classical description of the aqueous environment. For N{sub 2}O{sub 2}{sup -}, comparison of the calculated spectra and energetics with the experimental data reveals that: (1) upon the one-electron oxidation of trans-hyponitrite (ON=NO{sub 2}{sup -}), the trans configuration of the resulting ON=NO{sup -} radical is preserved; (2) although cis- and trans-ON=NO{sup -} are energetically nearly equivalent, the barrier for the trans-cis isomerization is prohibitively high due to the partial double character of the NN bond; (3) the UV spectrum of ON=NO{sup -} was misinterpreted in the earlier pulse radiolysis work and its more recent revision has been justified. For the N{sub 3}O{sub 3}{sup -} ion, the symmetric isomer is the dominant observable species, and the asymmetric isomer contributes little to the experimental spectrum. Coherent analysis of the calculated and experimental data suggests a re-interpretation of the N{sub 2}O{sub 2}{sup -} + NO reaction mechanism, according to which the reaction evenly bifurcates to yield both the symmetric and asymmetric isomers of N{sub 3}O{sub 3}{sup -}. While the latter isomer rapidly decomposes to the final NO{sub 2}{sup -} + N{sub 2}O products, the former isomer is stable toward this decomposition but its formation is reversible with the homolysis equilibrium constant Khom = 2.2 - 10{sup -7} M. Collectively, these results demonstrate that advanced theoretical modeling can be of significant benefit in structural and mechanistic analysis of UV spectra.

  19. Structural and Mechanistic Analysis through Electronic Spectra: Aqueous Hyponitrite Radical (N(2)O(2)(-)) and Nitrosyl Hyponitrite Anion (N(3)O(3)(-))

    SciTech Connect (OSTI)

    Lymar S. V.; Valiev M.

    2011-11-03

    Aqueous hyponitrite radical (N{sub 2}O{sub 2}{sup -}) and nitrosyl hyponitrite anion (N{sub 3}O{sub 3}{sup -}) are important intermediates in the reductive chemistry of NO. The structures and absorption spectra of various hydrated isomers of these compounds were investigated in this work using high-level quantum mechanical calculations combined with the explicit classical description of the aqueous environment. For N{sub 2}O{sub 2}{sup -}, comparison of the calculated spectra and energetics with the experimental data reveals that (1) upon the one-electron oxidation of trans-hyponitrite (ON{double_bond}NO{sup 2-}), the trans configuration of the resulting ON{double_bond}NO{sup -} radical is preserved; (2) although cis- and trans-ON{double_bond}NO{sup -} are energetically nearly equivalent, the barrier for the trans-cis isomerization is prohibitively high because of the partial double character of the NN bond; (3) the calculations confirm that the UV spectrum of ONNO{sup -} was misinterpreted in the earlier pulse radiolysis work, and its more recent revision has been justified. For the N{sub 3}O{sub 3}{sup -} ion, the symmetric isomer the dominant observable species, and the asymmetric isomer contributes insignificantly to the experimental spectrum. Coherent analysis of the calculated and experimental data suggests a reinterpretation of the N{sub 2}O{sub 2}{sup -} + NO reaction mechanism according to which the reaction evenly bifurcates to yield both the symmetric and asymmetric isomers of N{sub 3}O{sub 3}{sup -}. While the latter isomer rapidly decomposes to the final NO{sub 2}{sup -} + N{sub 2}O products, the former isomer is stable toward this decomposition, but its formation is reversible with the homolysis equilibrium constant K{sub hom} = 2.2 x 10{sup -7} M. Collectively, these results demonstrate that advanced theoretical modeling can be of significant benefit in structural and mechanistic analysis on the basis of the electronic spectra of aqueous transients.

  20. The H2O2+OH ? HO2+H2O reaction in aqueous solution from a charge-dependent continuum model of solvation

    SciTech Connect (OSTI)

    Ginovska, Bojana; Camaioni, Donald M.; Dupuis, Michel

    2008-07-07

    We applied our recently developed protocol of the conductor-like continuum model of solvation to describe the title reaction in aqueous solution. The model has the unique feature of the molecular cavity being dependent on the atomic charges in the solute, and can be extended naturally to transition states and reaction pathways. It was used to calculate the reaction energetics and reaction rate in solution for the title reaction. The rate of reaction calculated using canonical variational transition state theory CVT in the context of the equilibrium solvation path (ESP) approximation, and including correction for tunneling through the small curvature approximation (SCT) was found to be 3.6 106 M-1 s-1, in very good agreement with experiment, These results suggest that the present protocol of the conductor-like continuum model of solvation with the charge-dependent cavity definition captures accurately the solvation effects at transition states and allows for quantitative estimates of reaction rates in solutions. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

  1. CRITICAL CONFIGURATION FOR BERYLLIUM REFLECTED ASSEMBLIES OF U(93.15)O2 FUEL RODS (1.506-CM PITCH AND 7-TUBE CLUSTERS)

    SciTech Connect (OSTI)

    Margaret A. Marshall

    2012-05-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratorys Critical Experiments Facility in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s efforts were made to study power plants for the production of electrical power in space vehicles. The MPRE program was a part of those efforts and studied the feasibility of a stainless steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the programs effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of 253 unmoderated stainless steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector. The first two experiments in the series were evaluated in HEU-COMP-FAST-001 (SCCA-FUND-EXP-001) and HEU-COMP-FAST-002 (SCCA-FUND-EXP-002). The first experiment had the 253 fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank (References 1 and 2). The second experiment in the series, performed in early 1963, had the 253 fuel tubes at a 1.506-cm triangular lattice in a 25.96 cm OD core tank and graphite reflectors on all sides. The third set of experiments in the series, performed in mid-1963, which is studied in this evaluation, used beryllium reflectors. The beryllium reflected system was the preferred reactor configuration for this application because of the small thickness of the reflector. The two core configurations had the 253 fuel tubes at a 1.506-cm triangular lattice and arranged in 7-tube clusters. The experiments have been determined to represent acceptable benchmark experiments. Information for this evaluation was compiled from published reports on all three parts of the experimental series (Reference 1-5) and the experimental logbook as well as from communication with the experimenter, John T. Mihalczo.

  2. Direct synthesis of LiNi1/3Co1/3Mn1/3O2 from nitrateprecursors

    SciTech Connect (OSTI)

    Patoux, Sebastien; Doeff, Marca M.

    2004-04-28

    Two novel methods for synthesis of the title compound directly from metal nitrates are described. Phase-pure materials are produced when precursors are calcined between 600 and 1000 C, with little to no ion mixing exhibited for products heated to 900 C or above. The electrochemical characteristics of these materials depended upon calcination temperature and synthesis method, with results comparable to a commercial sample for the materials made at high temperatures in a one-step process without combustion. The sample prepared by combustion also exhibited very stable capacity retention upon cycling.

  3. Growth of aligned single-crystalline rutile TiO2 nanowires on arbitrary substrates and their application in dye-sensitized solar cells

    SciTech Connect (OSTI)

    Kumar, Akshay; Madaria, Anuj R.; Zhou, Chongwu

    2010-05-06

    TiO{sub 2} is a wide band gap semiconductor with important applications in photovoltaic cells and photocatalysis. In this paper, we report synthesis of single-crystalline rutile phase TiO{sub 2} nanowires on arbitrary substrates, including fluorine-doped tin oxide (FTO), glass slides, tin-doped indium oxide (ITO), Si/SiO{sub 2}, Si(100), Si(111), and glass rods. By controlling the growth parameters such as growth temperature, precursor concentrations, and so forth, we demonstrate that anisotropic growth of TiO{sub 2} is possible leading to various morphologies of nanowires. Optimization of the growth recipe leads to well-aligned vertical array of TiO{sub 2} nanowires on both FTO and glass substrates. Effects of various titanium precursors on the growth kinetics, especially on the growth rate of nanowires, are also studied. Finally, application of vertical array of TiO{sub 2} nanowires on FTO as the photoanode is demonstrated in dye-sensitized solar cell with an efficiency of 2.9 0.2%.

  4. Zn2+ and Sr2+ Adsorption at the TiO2 (110)-Electrolyte Interface: Influence of Ionic Strength, Coverage, and Anions

    SciTech Connect (OSTI)

    Zhang,Z.; Fenter, P.; Cheng, L.; Sturchio, N.; Bedzyk, M.; Machesky, M.; Anovitz, L.; Wesolowski, D.

    2006-01-01

    The X-ray standing wave technique was used to probe the sensitivity of Zn{sup 2+} and Sr{sup 2+} ion adsorption to changes in both the adsorbed ion coverage and the background electrolyte species and concentrations at the rutile ({alpha}-TiO{sub 2}) (110)-aqueous interface. Measurements were made with various background electrolytes (NaCl, NaTr, RbCl, NaBr) at concentrations as high as 1 m. The results demonstrate that Zn{sub 2+} and Sr{sub 2+} reside primarily in the condensed layer and that the ion heights above the Ti-O surface plane are insensitive to ionic strength and the choice of background electrolyte (with <0.1 Angstroms changes over the full compositional range). The lack of any specific anion coadsorption upon probing with Br{sup -}, coupled with the insensitivity of Zn{sup 2+} and Sr{sup 2+} cation heights to changes in the background electrolyte, implies that anions do not play a significant role in the adsorption of these divalent metal ions to the rutile (110) surface. Absolute ion coverage measurements for Zn{sup 2+} and Sr{sup 2+} show a maximum Stern-layer coverage of {approx}0.5 monolayer, with no significant variation in height as a function of Stern-layer coverage. These observations are discussed in the context of Gouy-Chapman-Stern models of the electrical double layer developed from macroscopic sorption and pH-titration studies of rutile powder suspensions. Direct comparison between these experimental observations and the MUltiSIte Complexation (MUSIC) model predictions of cation surface coverage as a function of ionic strength revealed good agreement between measured and predicted surface coverages with no adjustable parameters.

  5. Angle Resolved Photoemission Spectroscopy Studies of the Mott Insulator to Superconductor Evolution in Ca2-xNaxCuO2Cl2

    SciTech Connect (OSTI)

    Shen, Kyle Michael; ,

    2005-09-02

    It is widely believed that many of the exotic physical properties of the high-T{sub c} cuprate superconductors arise from the proximity of these materials to the strongly correlated, antiferromagnetic Mott insulating state. Therefore, one of the fundamental questions in the field of high-temperature superconductivity is to understand the insulator-to-superconductor transition and precisely how the electronic structure of Mott insulator evolves as the first holes are doped into the system. This dissertation presents high-resolution, doping dependent angle-resolved photoemission (ARPES) studies of the cuprate superconductor Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2}, spanning from the undoped parent Mott insulator to a high-temperature superconductor with a T{sub c} of 22 K. A phenomenological model is proposed to explain how the spectral lineshape, the quasiparticle band dispersion, and the chemical potential all progress with doping in a logical and self-consistent framework. This model is based on Franck-Condon broadening observed in polaronic systems where strong electron-boson interactions cause the quasiparticle residue, Z, to be vanishingly small. Comparisons of the low-lying states to different electronic states in the valence band strongly suggest that the coupling of the photohole to the lattice (i.e. lattice polaron formation) is the dominant broadening mechanism for the lower Hubbard band states. Combining this polaronic framework with high-resolution ARPES measurements finally provides a resolution to the long-standing controversy over the behavior of the chemical potential in the high-T{sub c} cuprates. This scenario arises from replacing the conventional Fermi liquid quasiparticle interpretation of the features in the Mott insulator by a Franck-Condon model, allowing the reassignment of the position of the quasiparticle pole. As a function of hole doping, the chemical potential shifts smoothly into the valence band while spectral weight is transferred from incoherent weight at high energies to a coherent quasiparticle peak near E{sub F}. The combined shift in the chemical potential and Fermi wavevector, k{sub F}, closely corresponds to a rigid band shift into the faint excitation branch defined by the low-energy quasiparticles. In addition, the detailed doping evolution of the low-energy excitations has been studied throughout k-space. A large, hole-like contour emerges with doping, although well-defined quasiparticle peaks are only observed along a small arc around the (0, 0)-({pi},{pi}) nodal line. Near the ({pi}, 0) antinodes, faint parallel segments are found with a nesting wavevector and energy dependence very similar to the 4a{sub 0} x 4a{sub 0} checkerboard pattern observed by scanning tunneling microscopy. However, these measurements reveal a striking dichotomy between the real and momentum-space probes, where antinodal charge ordering is emphasized in the tunnelling measurements, while ARPES is most sensitive to excitations near the d-wave nodal line. These results emphasize the importance of momentum anisotropy in determining the complex electronic properties of the cuprates and places strong constraints on theoretical models of the charge ordered state.

  6. CRITICAL CONFIGURATION AND PHYSICS MEASUREMENTS FOR BERYLLIUM REFLECTED ASSEMBLIES OF U(93.15)O2 FUEL RODS (1.506-CM PITCH)

    SciTech Connect (OSTI)

    Margaret A. Marshall

    2013-03-01

    Cadmium ratios were measured with enriched uranium metal foils at various locations in the assembly with the fuel tube at the 1.506-cm spacing. They are described in the following subsections. The experiment configuration was the same as the first critical configuration described in HEU-COMP-FAST-004 (Case 1). The experimenter placed 0.75-cm-diameter 0.010-cm-thick 93.15%-235U-enriched uranium metal foils with and without 0.051-cm-thick cadmium covers at various locations in the core and top reflector. One part of the cadmium cover was cupshape and contained the uranium foil. The other part was a lid that fit over the exposed side of the foil when it was in the cup shaped section of the cover. As can be seen in the logbook, two runs were required to obtain all the measurements necessary for the cadmium ratio. The bare foil measurements within the top reflector were run first as part of the axial foil activation measurements. The results of this run are used for both the axial activation results and the cadmium ratios. Cadmium covered foils were then placed at the same location through the top reflector in a different run. Three pairs of bare and cadmium covered foils were also placed through the core tank. One pair was placed at the axial center of a fuel tube 11.35 cm from the center of the core. Two pairs of foils were placed on top of fuel tubes 3.02 and 12.06 cm from the center of the core. The activation of the uranium metal foils was measured after removal from the assembly using two lead shielded NaI scintillation detectors as follows. The NaI scintillators were carefully matched and had detection efficiencies for counting delayed-fission-product gamma rays with energies above 250 KeV within 5%. In all foil activation measurements, one foil at a specific location was used as a normalizing foil to remove the effects of the decay of fission products during the counting measurements with the NaI detectors. The normalization foil was placed on one NaI scintillator and the other foil on the other NaI detector and the activities measured simultaneously. The activation of a particular foil was compared to that of the normalization foil by dividing the count rate for each foil by that of the normalization foil. To correct for the differing efficiencies of the two NaI detectors, the normalization foil was counted in Detector 1 simultaneously with the foil at position x in Detector 2, and then the normalization foil was counted simultaneously in Detector 2 with the foil from position x in Counter 1. The activity of the foil from position x was divided by the activity of the normalization foil counted simultaneously. This resulted in obtaining two values of the ratio that were then averaged. This procedure essentially removed the effect of the differing efficiencies of the two NaI detectors. Differing efficiencies of 10% resulted in errors in the ratios measured to less than 1%. The background counting rates obatined with the foils used for the measurements on the NaI detectors before their irradiation measurement were subtracted from all count rates. The results of the cadmium ratio measurements are given in Table 1.3-1 and Figure 1.3-1. No correction has been made for self shielding in the foils (Reference 3).

  7. TiO2 Nanotubes with a ZnO Thin Energy Barrier for Improved Current Efficiency of CdSe Quantum-Dot-Sensitized Solar Cells

    SciTech Connect (OSTI)

    Lee, W.; Kang, S. H.; Kim, J. Y.; Kolekar, G. B.; Sung, Y. E.; Han, S. H.

    2009-01-01

    This paper reports the formation of a thin ZnO energy barrier between a CdSe quantum dot (Q dots) sensitizer and TiO{sub 2} nanotubes (TONTs) for improved current efficiency of Q dot-sensitized solar cells. The formation of a ZnO barrier between TONTs and the Q dot sensitizer increased the short-circuit current under illumination and also reduced the dark current in a dark environment. The power conversion efficiency of Q dot-sensitized TONT solar cells increased by 25.9% in the presence of the ZnO thin layer due to improved charge-collecting efficiency and reduced recombination.

  8. Effect of metal in M3(btc)2 and M2(dobdc) MOFs for O2/N2 separations: A combined density functional theory and experimental study

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Parkes, Marie V.; Sava Gallis, Dorina F.; Greathouse, Jeffery A.; Nenoff, Tina M.

    2015-03-02

    Computational screening of metal-organic framework (MOF) materials for selective oxygen adsorption from air could lead to new sorbents for the oxyfuel combustion process feedstock streams. A comprehensive study on the effect of MOF metal chemistry on gas binding energies in two common but structurally disparate metal-organic frameworks has been undertaken. Dispersion-corrected density functional theory methods were used to calculate the oxygen and nitrogen binding energies with each of fourteen metals, respectively, substituted into two MOF series, M2(dobdc) and M3(btc)2. The accuracy of DFT methods was validated by comparing trends in binding energy with experimental gas sorption measurements. A periodic trendmore » in oxygen binding energies was found, with greater oxygen binding energies for early transition-metal-substituted MOFs compared to late transition metal MOFs; this was independent of MOF structural type. The larger binding energies were associated with oxygen binding in a side-on configuration to the metal, with concomitant lengthening of the O-O bond. In contrast, nitrogen binding energies were similar across the transition metal series, regardless of both MOF structural type and metal identity. Altogether, these findings suggest that early transition metal MOFs are best suited to separating oxygen from nitrogen, and that the MOF structural type is less important than the metal identity.« less

  9. Hierarchical Heterogeneity at the CeO x –TiO 2 Interface: Electronic and Geometric Structural Influence on the Photocatalytic Activity of Oxide on Oxide Nanostructures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Luo, Si; Nguyen-Phan, Thuy-Duong; Johnston-Peck, Aaron C.; Barrio, Laura; Sallis, Shawn; Arena, Dario A.; Kundu, Shankhamala; Xu, Wenqian; Piper, Louis F. J.; Stach, Eric A.; et al

    2015-01-13

    Mixed oxide interfaces are critical for delivering active components of demanding catalytic processes such as the photo-catalytic splitting of water. We have studied CeOxTiO₂ catalysts with low ceria loadings of 1 wt%, 3 wt% and 6 wt% that were prepared with wet impregnation methods to favor a strong interaction between CeOx and TiO₂. In these materials the interfaces between CeOx-TiO₂ have been sequentially loaded (1%, 3% and 6%), with and without Pt (0.5 wt%). The structure and properties of the catalysts were characterized using several X-ray and electron based techniques including XRD, XPS, UPS, NEXAFS, UV-Vis and HR-STEM/STEM-EELS, to unravelmore » the local morphology, bulk structure, surface states and electronic structure. The combination of all these techniques allow us to analyze in a systematic way the complete structural and electronic properties that prevail at the CeOx-TiO₂ interface. Fluorite structured nano crystallites of ceria on anatase-structured titania were identified by both XRD and NEXAFS. A sequential increasing of the CeOx loading led to the formation of clusters, then plates and finally nano particles in a hierarchical manner on the TiO₂ support. The electronic structures of these catalysts indicate that the interaction between TiO₂ and CeO₂ is closely related to the local morphology of nanostructured CeO₂. Ce³⁺ cations were detected at the surface of CeO₂ and at the interface of the two oxides. In addition, the titania is perturbed by the interaction with ceria and also with Pt. The photocatalytic activity for the splitting of H₂O using UV light was measured for these materials and correlated with our understanding of the electronic and structural properties. Optimal catalytic performance and photo response results were found for the 1 wt% CeOx-TiO₂ catalyst where low dimensional geometry of the ceria provided ideal electronic and geometrical properties. The structural and electronic properties of the interface were critical for the photocatalytic performance of this mixed-oxide nanocatalyst system.« less

  10. An In-Situ XAS Study of the Structural Changes in a CuO-CeO2/Al2O3 Catalyst during Total Oxidation of Propane

    SciTech Connect (OSTI)

    Silversmith, Geert; Poelman, Hilde; Poelman, Dirk; Gryse, Roger de; Olea, Maria; Balcaen, Veerle; Heynderickx, Philippe; Marin, Guy B.

    2007-02-02

    A CuOx-CeOx/Al2O3 catalyst was studied with in-situ transmission Cu K XAS for the total oxidation of propane as model reaction for the catalytic elimination of volatile organic compounds. The local Cu structure was determined for the catalyst as such, after pre-oxidation and after reduction with propane. The catalyst as such has a local CuO structure. No structural effect was observed upon heating in He up to 600 deg. C or after pre-oxidation at 150 deg. C. A full reduction of the Cu2+ towards metallic Cu0 occurred, when propane was fed to the catalyst. The change in local Cu structure during propane reduction was followed with a time resolution of 1 min. The {chi}(k) scans appeared as linear combinations of start and end spectra, CuO and Cu structure, respectively. However, careful examination of the XANES edge spectra indicates the presence of a small amount of additional Cu1+ species.

  11. High Activity of Ce1-xNixO2-y for H2 Production through Ethanol Steam Reforming: Tuning Catalytic Performance through Metal-Oxide Interactions

    SciTech Connect (OSTI)

    G Zhou; L Barrio; S Agnoli; S Senanayake; J Evans; A Kubacka; M Estrella; J Hanson; A Martinez-Arias; et al.

    2011-12-31

    The importance of the oxide: Ce{sub 0.8}Ni{sub 0.2}O{sub 2-y} is an excellent catalyst for ethanol steam reforming. Metal-oxide interactions perturb the electronic properties of the small particles of metallic nickel present in the catalyst under the reaction conditions and thus suppress any methanation activity. The nickel embedded in ceria induces the formation of O vacancies, which facilitate cleavage of the OH bonds in ethanol and water.

  12. Intermixing of InGaAs/GaAs Quantum Well Using Multiple Cycles Annealing Cu-doped SiO2

    SciTech Connect (OSTI)

    Hongpinyo, V; Ding, Y H; Dimas, C E; Wang, Y; Ooi, B S; Qiu, W; Goddard, L L; Behymer, E M; Cole, G D; Bond, T C

    2008-06-11

    The authors investigate the effect of intermixing in InGaAs/GaAs quantum well structure using Cu-doped SiO{sub 2}. The incorporation of Cu into the silica film yields larger bandgap shift than typical impurity-free vacancy diffusion (IFVD) method at a lower activation temperature. We also observe enhancement of the photoluminescence (PL) signal from the intermixed InGaAs/GaAs quantum well structure after being cycle-annealed at 850 C.

  13. Nuclear resonance vibrational spectroscopy reveals the FeS cluster composition and active site vibrational properties of an O2-tolerant NAD+-reducing [NiFe] hydrogenase

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lauterbach, Lars; Wang, Hongxin; Horch, Marius; Gee, Leland B.; Yoda, Yoshitaka; Tanaka, Yoshihito; Zebger, Ingo; Lenz, Oliver; Cramer, Stephen P.

    2014-10-30

    Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H2 conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by 57Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, whichmore »is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD+-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective 13C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors.« less

  14. Measurements and modeling of HO2 formation in the reactions of n-C3H7 and i-C3H7 radicals with O2.

    SciTech Connect (OSTI)

    Taatjes, Craig A.; Estupinan, Edgar Garcia; Klippenstein, Stephen J.

    2004-08-01

    The formation of HO{sub 2} in the reactions of C{sub 2}H{sub 5}, n-C{sub 3}H{sub 7}, and i-C{sub 3}H{sub 7} radicals with O{sub 2} is investigated using the technique of laser photolysis/long-path frequency-modulation spectroscopy. The alkyl radicals are formed by 266 nm photolysis of alkyl iodides. The formation of HO{sub 2} from the subsequent reaction of the alkyl radicals with O{sub 2} is followed by infrared frequency-modulation spectroscopy. The concentration of I atoms is simultaneously monitored by direct absorption of a second laser probe on the spin?orbit transition. The measured profiles are compared to a kinetic model taken from time-resolved master-equation results based on previously published ab initio characterizations of the relevant stationary points on the potential-energy surface. The ab initio energies are adjusted to produce agreement with the present experimental data and with available literature studies. The isomer specificity of the present results enables refinement of the model for i-C{sub 3}H{sub 7} + O{sub 2} and improved agreement with experimental measurements of HO{sub 2} production in propane oxidation.

  15. High Cyclability of Ionic Liquid-Produced TiO2 Nanotube Arrays As an Anode Material for Lithium-Ion Batteries

    SciTech Connect (OSTI)

    Li, Huaqing; Martha, Surendra K; Unocic, Raymond R; Luo, Huimin; Dai, Sheng; Qu, Jun

    2012-01-01

    TiO{sub 2} nanotubes (NTs) are considered as a potential SEI-free anode material for Li-ion batteries to offer enhanced safety. Organic solutions, dominatingly ethylene glycol (EG)-based, have widely been used for synthesizing TiO{sub 2} NTs via anodization because of their ability to generate long tubes and well-aligned structures. However, it has been revealed that the EG-produced NTs are composited with carbonaceous decomposition products of EG, release of which during the tube crystallization process inevitably causes nano-scale porosity and cracks. These microstructural defects significantly deteriorate the NTs charge transport efficiency and mechanical strength/toughness. Here we report using ionic liquids (ILs) to anodize titanium to grow low-defect TiO{sub 2} NTs by reducing the electrolyte decomposition rate (less IR drop due to higher electrical conductivity) as well as the chance of the decomposition products mixing into the TiO{sub 2} matrix (organic cations repelled away). Promising electrochemical results have been achieved when using the IL-produced TiO{sub 2} NTs as an anode for Li-ion batteries. The ILNTs demonstrated excellent capacity retention without microstructural damage for nearly 1200 cycles of charge-discharge, while the NTs grown in a conventional EG solution totally pulverized in cycling, resulting in significant capacity fade.

  16. Removing Structural Disorder from Oriented TiO2 Nanotube Arrays: Reducing the Dimensionality of Transport and Recombination in Dye-Sensitized Solar Cells

    SciTech Connect (OSTI)

    Zhu, K.; Vinzant, T. B.; Neale, N. R.; Frank, A. J.

    2007-01-01

    We report on the influence of morphological disorder, arising from bundling of nanotubes (NTs) and microcracks in films of oriented TiO{sub 2} NT arrays, on charge transport and recombination in dye-sensitized solar cells (DSSCs). Capillary stress created during evaporation of liquids from the mesopores of dense TiO{sub 2} NT arrays was of sufficient magnitude to induce bundling and microcrack formation. The average lateral deflection of the NTs in the bundles increased with the surface tension of the liquids and with the film thicknesses. The supercritical CO{sub 2} drying technique was used to produce bundle-free and crack-free NT films. Charge transport and recombination properties of sensitized films were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. Transport became significantly faster with decreased clustering of the NTs, indicating that bundling creates additional pathways via intertube contacts. Removing such contacts alters the transport mechanism from a combination of one and three dimensions to the expected one dimension and shortens the electron-transport pathway. Reducing intertube contacts also resulted in a lower density of surface recombination centers by minimizing distortion-induced surface defects in bundled NTs. A causal connection between transport and recombination is observed. The dye coverage was greater in the more aligned NT arrays, suggesting that reducing intertube contacts increases the internal surface area of the films accessible to dye molecules. The solar conversion efficiency and photocurrent density were highest for DSSCs incorporating films with more aligned NT arrays owing to an enhanced light-harvesting efficiency. Removing structural disorder from other materials and devices consisting of nominally one-dimensional architectures (e.g., nanowire arrays) should produce similar effects.

  17. Constructing Ordered Sensitized Heterojunctions: Bottom-Up Electrochemical Synthesis of p-Type Semiconductors in Oriented n-TiO2 Nanotube Arrays

    SciTech Connect (OSTI)

    Wang, Q.; Zhu, K.; Neale, N. R.; Frank. A. J.

    2009-01-01

    Fabrication of efficient semiconductor-sensitized bulk heterojunction solar cells requires the complete filling of the pore system of one semiconductor (host) material with nanoscale dimensions (<100 nm) with a different semiconductor (guest) material. Because of the small pore size and electrical conductivity of the host material, it is challenging to employ electrochemical approaches to fill the entire pore network. Typically, during the electrochemical deposition process, the guest material blocks the pores of the host, precluding complete pore filling. We describe a general synthetic strategy for spatially controlling the growth of p-type semiconductors in the nanopores of electrically conducting n-type materials. As an illustration of this strategy, we report on the facile electrochemical deposition of p-CuInSe{sub 2} in nanoporous anatase n-TiO{sub 2} oriented nanotube arrays and nanoparticle films. We show that by controlling the ambipolar diffusion length the p-type semiconductors can be deposited from the bottom-up, resulting in complete pore filling.

  18. AISI/DOE Technology Roadmap Program: Development of an O2-Enriched Furnace System for Reduced CO2 and NOx Emissions For the Steel Industry

    SciTech Connect (OSTI)

    Edward W. Grandmaison; David J. Poirier; Eric Boyd

    2003-01-20

    An oxygen-enriched furnace system for reduced CO2 and NOx emission has been developed. The furnace geometry, with a sidewall-mounted burner, was similar to configurations commonly encountered in a steel reheat furnace. The effect of stack oxygen concentration, oxygen enrichment level and air infiltration on fuel savings/CO2 reduction, NOx emissions and scale formation were investigated. The firing rate required to maintain the furnace temperature at 1100 C decreased linearly with increasing oxygen enrichment. At full oxygen enrichment a reduction of 40-45% in the firing rate was required to maintain furnace temperature. NOx emissions were relatively constant at oxygen enrichment levels below 60% and decreased concentration at all oxygen enrichment levels. Air infiltration also had an effect on NOx levels leading to emissions similar to those observed with no air infiltration but with similar stack oxygen concentrations. At high oxygen enrichment levels, there was a larger variation in the refractory surface-temperature on the roof and blind sidewall of the furnace. Scale habit, intactness, adhesion and oxidation rates were examined for five grades of steel over a range of stack oxygen concentrations and oxygen enrichment levels at 1100 degree C. The steel grade had the largest effect on scaling properties examined in this work. The stack oxygen concentration and the oxygen enrichment level had much smaller effects on the scaling properties.

  19. Nuclear resonance vibrational spectroscopy reveals the FeS cluster composition and active site vibrational properties of an O2-tolerant NAD+-reducing [NiFe] hydrogenase

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lauterbach, Lars; Wang, Hongxin; Horch, Marius; Gee, Leland B.; Yoda, Yoshitaka; Tanaka, Yoshihito; Zebger, Ingo; Lenz, Oliver; Cramer, Stephen P.

    2014-10-30

    Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H2 conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by 57Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, whichmore » is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD+-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective 13C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors.« less

  20. In Situ Time-Resolved Characterization of Novel Cu-MoO2 Catalysts During the Water-Gas Shift Reaction

    SciTech Connect (OSTI)

    Wen ,W.; Liu, J.; White, M.; Marinkovic, N.; Hanson, J.; Rodriguez, J.

    2007-01-01

    A novel and active Cu-MoO{sub 2} catalyst was synthesized by partial reduction of a precursor CuMoO{sub 4} mixed-metal oxide with CO or H{sub 2} at 200-250 C. The phase transformations of Cu-MoO{sub 2} during H{sub 2} reduction and the water-gas shift reaction could be followed by In situ time resolved XRD techniques. During the reduction process the diffraction pattern of the CuMoO{sub 4} collapsed and the copper metal lines were observed on an amorphous material background that was assigned to molybdenum oxides. During the first pass of water-gas shift (WGS) reaction, diffraction lines for Cu{sub 6}Mo{sub 5}O{sub 18} and MoO{sub 2} appeared around 350 C and Cu{sub 6}Mo{sub 5}O{sub 18} was further transformed to Cu/MoO{sub 2} at higher temperature. During subsequent passes, significant WGS catalytic activity was observed with relatively stable plateaus in product formation around 350, 400 and 500 C. The interfacial interactions between Cu clusters and MoO{sub 2} increased the water-gas shift catalytic activities at 350 and 400 C.

  1. CRITICAL CONFIGURATION AND PHYSICS MEASUREMENTS FOR BERYLLIUM REFLECTED ASSEMBLIES OF U(93.15)O2 FUEL RODS (1.506-CM PITCH AND 7-TUBE CLUSTERS)

    SciTech Connect (OSTI)

    Margaret A. Marshall

    2014-03-01

    Cadmium ratios were measured with enriched uranium metal foils at various locations in the assembly with the fuel tube at the 1.506-cm spacing. They are described in the following subsections. The experiment configuration was the same as the first critical configuration described in HEU-COMP-FAST-004 (Case 1). The experimenter placed 0.75-cm-diameter 0.010-cm-thick 93.15%-235U-enriched uranium metal foils with and without 0.051-cm-thick cadmium covers at various locations in the core and top reflector. One part of the cadmium cover was cupshape and contained the uranium foil. The other part was a lid that fit over the exposed side of the foil when it was in the cup shaped section of the cover. As can be seen in the logbook, two runs were required to obtain all the measurements necessary for the cadmium ratio. The bare foil measurements within the top reflector were run first as part of the axial foil activation measurements. The results of this run are used for both the axial activation results and the cadmium ratios. Cadmium covered foils were then placed at the same location through the top reflector in a different run. Three pairs of bare and cadmium covered foils were also placed through the core tank. One pair was placed at the axial center of a fuel tube 11.35 cm from the center of the core. Two pairs of foils were placed on top of fuel tubes 3.02 and 12.06 cm from the center of the core. The activation of the uranium metal foils was measured after removal from the assembly using two lead shielded NaI scintillation detectors as follows. The NaI scintillators were carefully matched and had detection efficiencies for counting delayed-fission-product gamma rays with energies above 250 KeV within 5%. In all foil activation measurements, one foil at a specific location was used as a normalizing foil to remove the effects of the decay of fission products during the counting measurements with the NaI detectors. The normalization foil was placed on one NaI scintillator and the other foil on the other NaI detector and the activities measured simultaneously. The activation of a particular foil was compared to that of the normalization foil by dividing the count rate for each foil by that of the normalization foil. To correct for the differing efficiencies of the two NaI detectors, the normalization foil was counted in Detector 1 simultaneously with the foil at position x in Detector 2, and then the normalization foil was counted simultaneously in Detector 2 with the foil from position x in Counter 1. The activity of the foil from position x was divided by the activity of the normalization foil counted simultaneously. This resulted in obtaining two values of the ratio that were then averaged. This procedure essentially removed the effect of the differing efficiencies of the two NaI detectors. Differing efficiencies of 10% resulted in errors in the ratios measured to less than 1%. The background counting rates obatined with the foils used for the measurements on the NaI detectors before their irradiation measurement were subtracted from all count rates. The results of the cadmium ratio measurements are given in Table 1.3-1 and Figure 1.3-1. No correction has been made for self shielding in the foils (Reference 3).

  2. Why Lighting Systems will become more connected?

    Energy Savers [EERE]

    November 16, 2015 Why Lighting Systems will become more connected? Agenda What is the Internet of Things? Why would I want to do that? How would I do that? Challenges? 1 2 3 4 IoT...

  3. The Internet of Things Helping Utilities | OpenEI Community

    Open Energy Info (EERE)

    The Internet of Things Helping Utilities Home > Groups > Smart Grid Dc's picture Submitted by Dc(266) Contributor 16 October, 2014 - 12:21 The Internet of Things (IoT) is helping...

  4. BPA-2013-00569-FOIA Request

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    description: RL(1IVEi) BY BPA IOtA OFFICE THIS DUE DATE: 3W I3 LOG CO*fF 2202013 Hello, I am looking for current or 2012 salary records for Power Operations employees....

  5. Development of a 402.5 MHz 140 kW Inductive Output Tube

    SciTech Connect (OSTI)

    R. Lawrence Ives; Michael Read, Robert Jackson

    2012-05-09

    This report contains the results of Phase I of an SBIR to develop a Pulsed Inductive Output Tube (IOT) with 140 kW at 400 MHz for powering H-proton beams. A number of sources, including single beam and multiple beam klystrons, can provide this power, but the IOT provides higher efficiency. Efficiencies exceeding 70% are routinely achieved. The gain is typically limited to approximately 24 dB; however, the availability of highly efficient, solid state drivers reduces the significance of this limitation, particularly at lower frequencies. This program initially focused on developing a 402 MHz IOT; however, the DOE requirement for this device was terminated during the program. The SBIR effort was refocused on improving the IOT design codes to more accurately simulate the time dependent behavior of the input cavity, electron gun, output cavity, and collector. Significant improvement was achieved in modeling capability and simulation accuracy.

  6. Evaluation of Cadmium Ratio and Foil Activation Measurements for a Beryllium-Reflected Assembly of U(93.15)O2 Fuel Rods (1.506-cm Triangular Pitch)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Marshall, Margaret A.

    2014-11-04

    A series of small, compact critical assembly (SCCA) experiments were completed from 1962 to 1965 at Oak Ridge National Laboratory’s Critical Experiments Facility (ORCEF) in support of the Medium-Power Reactor Experiments (MPRE) program. Initial experiments, performed in November and December of 1962, consisted of a core of un-moderated stainless-steel tubes, each containing 26 UOIdaho National Laboratory (INL), Idaho Falls, ID (United States) fuel pellets, surrounded by a graphite reflector. Measurements were performed to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. The graphite reflectors were then changed to beryllium reflectors. For the beryllium reflected assemblies, the fuel wasmore » in 1.506-cm-triangular and 7-tube clusters leading to two critical configurations. Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements, performed on the 1.506-cm-array critical configuration, have been evaluated and are described in this paper.« less

  7. Elimination of GeO(2) And Ge(3)N(4) Interfacial Transition Regions And Defects at N-Type Ge Interfaces: a Pathway for Formation of N-MOS Devices on Ge Substrates

    SciTech Connect (OSTI)

    Lucovsky, G.; Lee, S.; Long, J.P.; Seo, H.; Luning, J.

    2009-05-19

    The contribution from relatively low-K SiON interfacial transition regions (ITRs) between Si and transition metal (TM) gate dielectrics places a significant limitation on equivalent oxide thickness (EOT) scaling for Si complementary metal-oxide-semiconductor (CMOS) devices. This limitation is equally significant and limiting for Ge CMOS devices. Low-K Ge-based ITRs in Ge devices have also been shown to limit performance and reliability, particular for n-MOS field effect transistors. This article identifies the source of significant electron trapping at interfaces between n-Ge or inverted p-Ge, and Ge oxide, nitride and oxynitride ITRs. This is shown to be an interfacial band alignment issue in which native Ge ITRs have conduction band offset energies smaller than those of TM dielectrics, and trap electrons for negative Ge substrate bias. This article also describes a novel remote plasma processing approach for effectively eliminating any significant native Ge ITRs and using a plasma-processing/annealing process sequence for bonding TM gate dielectrics directly to the Ge substrate surface.

  8. High-Resolution Numerical Simulation and Analysis of Mach Reflection Structures in Detonation Waves in Low-Pressure H 2 –O 2 –Ar Mixtures: A Summary of Results Obtained with the Adaptive Mesh Refinement Framework AMROC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Deiterding, Ralf

    2011-01-01

    Numerical simulation can be key to the understanding of the multidimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the nonequilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniquesmore » in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis, and a diagram of the transition boundaries between possible Mach reflection structures is constructed.« less

  9. High-Resolution Numerical Simulation and Analysis of Mach Reflection Structures in Detonation Waves in Low-Pressure H2O2Ar Mixtures: A Summary of Results Obtained with the Adaptive Mesh Refinement Framework AMROC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Deiterding, Ralf

    2011-01-01

    Numerical simulation can be key to the understanding of the multidimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the nonequilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniquesmorein practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis, and a diagram of the transition boundaries between possible Mach reflection structures is constructed.less

  10. BPA-2014-00554-FOIA Request

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    MunroChristy (BPA) - NN-1 Sent Wednesday, February 05, 2014 10:48 AM To: WUsou,Risa L (CONTR) - NN-1; WunKim S (BPA) - NN-1 Subject: 1W: records request NEW IOtA From: Sickinger,...

  11. A 30 MW, 200 MHz Inductive Output Tube for RF Accelerators

    SciTech Connect (OSTI)

    R. Lawrence Ives; Michael Read

    2008-06-19

    This program investigated development of a multiple beam inductive output tube (IOT) to produce 30 MW pulses at 200 MHz. The program was successful in demonstrating feasibility of developing the source to achieve the desired power in microsecond pulses with 70% efficiency. The predicted gain of the device is 24 dB. Consequently, a 200 kW driver would be required for the RF input. Estimated cost of this driver is approximately $1.25 M. Given the estimated development cost of the IOT of approximately $750K and the requirements for a test set that would significantly increase the cost, it was determined that development could not be achieved within the funding constraints of a Phase II program.

  12. An Advanced simulation Code for Modeling Inductive Output Tubes

    SciTech Connect (OSTI)

    Thuc Bui; R. Lawrence Ives

    2012-04-27

    During the Phase I program, CCR completed several major building blocks for a 3D large signal, inductive output tube (IOT) code using modern computer language and programming techniques. These included a 3D, Helmholtz, time-harmonic, field solver with a fully functional graphical user interface (GUI), automeshing and adaptivity. Other building blocks included the improved electrostatic Poisson solver with temporal boundary conditions to provide temporal fields for the time-stepping particle pusher as well as the self electric field caused by time-varying space charge. The magnetostatic field solver was also updated to solve for the self magnetic field caused by time changing current density in the output cavity gap. The goal function to optimize an IOT cavity was also formulated, and the optimization methodologies were investigated.

  13. Internet of Things | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Internet of Things The Internet of Things is the network of physical objects accessed through the Internet, as defined by technology analysts and visionaries. The Internet of Things is the network of physical objects accessed through the Internet, as defined by technology analysts and visionaries. While possibly creating efficiencies in areas such as advanced manufacturing and infrastructure design, production and resilience, the Internet of Things (IOT) also creates new and unknown

  14. Technical Meeting: Buildings Interoperability Vision | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Buildings Interoperability Vision Technical Meeting: Buildings Interoperability Vision On March 11-12, 2015, BTO held a technical meeting in Seattle to discuss the current landscape of buildings interoperability and hear from technology leaders about Internet of Things (IoT) and next generation buildings automation concepts and challenges. To help frame the vision discussion, BTO assembled experts representing a variety of stakeholder groups in the connected buildings area to discuss the

  15. Connected Buildings Interoperability Vision Webinar | Department of Energy

    Office of Environmental Management (EM)

    Connected Buildings Interoperability Vision Webinar Connected Buildings Interoperability Vision Webinar This webinar presented materials from DOE's Building Technologies Office's March 11-12 Buildings Interoperability Technical Meeting in Seattle, where industry and other experts discussed the emerging transformation of buildings into interconnected systems of devices, as inspired by Internet of Things (IoT) initiatives, as well as next-generation automation concepts and challenges. The webinar

  16. Hydrothermally Stable, Sulfur-Tolerant Platinum-Based Oxidation Catalysts

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    via Surface Modification of SiO2 with TiO2 and ZrO2 | Department of Energy Hydrothermally Stable, Sulfur-Tolerant Platinum-Based Oxidation Catalysts via Surface Modification of SiO2 with TiO2 and ZrO2 Hydrothermally Stable, Sulfur-Tolerant Platinum-Based Oxidation Catalysts via Surface Modification of SiO2 with TiO2 and ZrO2 This study demonstrates the feasibility of developing highly stable, sulfur-tolerant oxidation catalysts that use less Pt via surface modification of silica supports

  17. Hydrothermally Stable, Sulfur-Tolerant Platinum-Based Oxidation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Stable, Sulfur-Tolerant Platinum-Based Oxidation Catalysts via Surface Modification of SiO2 with TiO2 and ZrO2 Hydrothermally Stable, Sulfur-Tolerant Platinum-Based Oxidation...

  18. Multifuctional integrated sensors (MFISES).

    SciTech Connect (OSTI)

    Homeijer, Brian D.; Roozeboom, Clifton

    2015-10-01

    Many emerging IoT applications require sensing of multiple physical and environmental parameters for: completeness of information, measurement validation, unexpected demands, improved performance. For example, a typical outdoor weather station measures temperature, humidity, barometric pressure, light intensity, rainfall, wind speed and direction. Existing sensor technologies do not directly address the demand for cost, size, and power reduction in multi-paramater sensing applications. Industry sensor manufacturers have developed integrated sensor systems for inertial measurements that combine accelerometers, gyroscopes, and magnetometers, but do not address environmental sensing functionality. In existing research literature, a technology gap exists between the functionality of MEMS sensors and the real world applications of the sensors systems.

  19. 2016 SSL R&D Workshop Presentations Posted | Department of Energy

    Energy Savers [EERE]

    2016 SSL R&D Workshop Presentations Posted 2016 SSL R&D Workshop Presentations Posted February 17, 2016 - 4:02pm Addthis More than 260 attendees participated in the 13th annual DOE Solid-State Lighting R&D Workshop, held February 2-4 in Raleigh, NC. The workshop combined plenary and LED/OLED breakout sessions, with presentations from 60 experts addressing such diverse lighting topics as health and human factors, IoT, manufacturing challenges, and site-specific applications such as

  20. TAS::89 0927::TAS RECOVERY - The Lean Green Energy Controller Machine

    SciTech Connect (OSTI)

    Teeter, John; Wang, Gene; Moss, David

    2012-12-30

    Achieving efficiency improvements and providing demand-response programs have been identified as key elements of our national energy initiative. The residential market is the largest, yet most difficult, segment to engage in efforts to meet these objectives. This project developed Energy Management System that engages the consumer and enables Smart Grid services, applications, and business processes to address this need. Our innovative solution provides smart controller providing dynamic optimization of energy consumption for the residential energy consumer. Our solution extends the technical platform to include a cloud based Internet of Things (IoT) aggregation of data sensors and actuators the go beyond energy management and extend to life style services provided through compelling mobile and console based user experiences.

  1. Evaluation of a 1000 MW Commercial Ultra Super-Critical Coal...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of instantaneous O2 mass fraction in a hypothetical commercial scale 1000 MW, Ultra Super-Critical (USC) coal boiler Large eddy simulation prediction of instantaneous O2 mass...

  2. Slide 1

    Office of Environmental Management (EM)

    design Provides in-reactor data for the release and speciation of tritium from -lithium aluminate (-LiAlO 2 ) and cermet (-LiAlO 2 in Zr) pellets Data collected as a...

  3. Invoking any Intel compiler with a Cray wrapper with -g defaults...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with a Cray wrapper with -g defaults to -O2 optimization contrary to the Intel compiler man pages Invoking any Intel compiler with a Cray wrapper with -g defaults to -O2...

  4. Design and Fabrication of In-Reactor Experiment to Measure Tritium...

    Office of Environmental Management (EM)

    Design and Fabrication of In-Reactor Experiment to Measure Tritium Release and Speciation from LiAlO2 and LiAlO2Zr Cermets Design and Fabrication of In-Reactor Experiment to...

  5. Strain-induced phase and oxygen-vacancy stability in ionic interfaces from first-principles calculations

    SciTech Connect (OSTI)

    Aidhy, Dilpuneet S; Liu, Bin; Zhang, Yanwen; Weber, William J

    2014-01-01

    Understanding interfacial chemistry is becoming crucial in materials design for heterointerfaces. Using density functional theory, we elucidate the effect of strained interfaces on phase and oxygen-vacancy stability for CeO2 | ZrO2, ThO2 | ZrO2 and CeO2 | ThO2 interfaces. The calculations show that ZrO2 transforms from cubic fluorite to the orthorhombic columbite under tensile strain providing evidence of a previous experimental speculation of an unrecognized ZrO2 phase. We also show that oxygen vacancies could be preferably stabilized on either side of the interface by manipulating strain. We predict that they are stable in tensile-strain, and unstable in compressivestrained materials.

  6. Fracture Characterization in Enhanced Geothermal Systems by Wellbore and Reservoir Analysis

    Broader source: Energy.gov [DOE]

    Project Summary. To study the transport and recovery of injected SiO2 nanoparticles through a longer flow path.

  7. On the mechanical stability of uranyl peroxide hydrates: Implications for nuclear fuel degradation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Weck, Philippe F.; Kim, Eunja; Buck, Edgar C.

    2015-09-11

    The mechanical properties and stability of studtite, (UO2)(O2)(H2O)2·2H2O, and metastudtite, (UO2)(O2)(H2O)2, two important corrosion phases observed on spent nuclear fuel exposed to water, have been investigated using density functional perturbation theory. While (UO2)(O2)(H2O)2 satisfies the necessary and sufficient Born criteria for mechanical stability, (UO2)(O2)(H2O)2·2H2O is found to be mechanically metastable, which might be the underlying cause of the irreversibility of the studtite to metastudtite transformation. According to Pugh's and Poisson's ratios and the Cauchy pressure, both phases are considered ductile and shear modulus is the parameter limiting their mechanical stability. Furthermore, debye temperatures of 294 and 271 K are predictedmore » for polycrystalline (UO2)(O2)(H2O)2·2H2O and (UO2)(O2)(H2O)2, suggesting a lower micro-hardness of metastudtite.« less

  8. Development of Compact Gaseous Sensors with Internal Reference for

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Monitoring O2 and NOx in Combustion Environments | Department of Energy Compact Gaseous Sensors with Internal Reference for Monitoring O2 and NOx in Combustion Environments Development of Compact Gaseous Sensors with Internal Reference for Monitoring O2 and NOx in Combustion Environments Compact sensors have been developed to allow for real-time monitoring of O2 and NOx during combustion. PDF icon deer08_singh.pdf More Documents & Publications Compact Electrochemical Bi-functional NOx/O2

  9. Investigation of crystallization processes from hafnium silicate powders prepared from an oxychloride sol-gel

    SciTech Connect (OSTI)

    McGilvery, Catriona M.; De Gendt, S; Payzant, E Andrew; Craven, A J; MacKenzie, M; McComb, D W

    2012-01-01

    Hafnium oxide and silicate materials are now incorporated into working CMOS devices, however the crystallisation mechanism is still poorly understood. In particular, addition of SiO2 to HfO2 has been shown to increase the crystallisation temperature of HfO2 hence allowing it to remain amorphous under current processing conditions. Building on earlier work we here investigate bulk HfxSi1-xO2 samples to determine the effect of SiO2 on the crystallisation pathway. Techniques such as XRD, HTXRD, thermal analysis techniques and TEM are used. It is found that the addition of SiO2 has very little affect on the crystallisation path at temperatures below 900 C but at higher temperatures a second t-HfO2 phase nucleates and is stabilised due to the strain of the surrounding amorphous SiO2 material. With an increase in SiO2 content the temperature at which this nucleation and stabilisation occurs is increased. The effect of strain has implications for inhibiting the crystallisation of the high-k layer, reduction of grain boundaries and hence diffusion, reduction of formation of interface layers and the possibility of stabilising t-HfO2 rather than m-HfO2 hence increasing the dielectric of the layer.

  10. High Dose Neutron Irradiation Performance of Dielectric Mirrors

    SciTech Connect (OSTI)

    Nimishakavi, Anantha Phani Kiran Kumar; Leonard, Keith J; Jellison Jr, Gerald Earle; Snead, Lance Lewis

    2015-01-01

    The study presents the high-dose behavior of dielectric mirrors specifically engineered for radiation-tolerance: alternating layers of Al2O3/SiO2 and HfO2/SiO2 were grown on sapphire substrates and exposed to neutron doses of 1 and 4 dpa at 458 10K in the High Flux Isotope Reactor (HFIR). In comparison to previously reported results, these higher doses of 1 and 4 dpa results in a drastic drop in optical reflectance, caused by a failure of the multilayer coating. HfO2/SiO2 mirrors failed completely when exposed to 1 dpa, whereas the reflectance of Al2O3/SiO2 mirrors reduced to 44%, eventually failing at 4 dpa. Transmission electron microscopy (TEM) observation of the Al2O3/SiO2 specimens showed SiO2 layer defects which increases size with irradiation dose. The typical size of each defect was 8 nm in 1 dpa and 42 nm in 4 dpa specimens. Buckling type delamination of the interface between the substrate and first layer was typically observed in both 1 and 4 dpa HfO2/SiO2 specimens. Composition changes across the layers were measured in high resolution scanning-TEM mode using energy dispersive spectroscopy. A significant interdiffusion between the film layers was observed in Al2O3/SiO2 mirror, though less evident in HfO2/SiO2 system. The ultimate goal of this work is the provide insight into the radiation-induced failure mechanisms of these mirrors.

  11. SISGR-Fundamental Experimental and Theoretical Studies on a Novel Family of Oxide Catalyst Supports for Water Electrolysis

    SciTech Connect (OSTI)

    Kumta, Prashant

    2014-10-03

    Identification and development of non-noble metal based electro-catalysts or electro-catalysts with significant reduction of expensive noble metal contents (E.g. IrO2, Pt) with comparable electrochemical performance as the standard noble metal/metal oxide for proton exchange membrane (PEM) based water electrolysis would constitute a major breakthrough in the generation of hydrogen by water electrolysis. Accomplishing such a system would not only result reduction of the overall capital costs of PEM based water electrolyzers, but also help attain the targeted hydrogen production cost [< $ 3.0 / gallon gasoline equivalent (gge)] comparable to conventional liquid fuels. In line with these goals, it was demonstrated that fluorine doped IrO2 thin films and nanostructured high surface area powders display remarkably higher electrochemical activity, and comparable durability as pure IrO2 electro-catalyst for the oxygen evolution reaction (OER) in PEM based water electrolysis. Furthermore, corrosion resistant SnO2 and NbO2 support has been doped with F and coupled with IrO2 or RuO2 for use as an OER electro-catalyst. A solid solution of SnO2:F or NbO2:F with only 20 - 30 mol.% IrO2 or RuO2 yielding a rutile structure in the form of thin films and bulk nanoparticles displays similar electrochemical activity and stability as pure IrO2/RuO2. This would lead to more than 70 mol.% reduction in the noble metal oxide content. Novel nanostructured ternary (Ir,Sn,Nb)O2 thin films of different compositions FUNDAMENTAL STUDY OF NANOSTRUCTURED ELECTRO-CATALYSTS WITH REDUCED NOBLE METAL CONTENT FOR PEM BASED WATER ELECTROLYSIS 4 have also been studied. It has been shown that (Ir0.40Sn0.30Nb0.30)O2 shows similar electrochemical activity and enhanced chemical robustness as compared to pure IrO2. F doping of the ternary (Ir,Sn,Nb)O2 catalyst helps in further decreasing the noble metal oxide content of the catalyst. As a result, these reduced noble metal oxide catalyst systems would potentially be preferred as OER electro-catalysts for PEM electrolysis. The excellent performance of the catalysts coupled with its robustness would make them great candidates for contributing to significant reduction in the overall capital costs of PEM based water electrolyzers. This s.thesis provides a detailed fundamental study of the synthesis, materials, characterization, theoretical studies and detailed electrochemical response and potential mechanisms of these novel electro-catalysts for OER processes.

  12. Sensitivity of UO2 Stability in a Reducing Environment on Radiolysis Model Parameters

    SciTech Connect (OSTI)

    Wittman, Richard S.; Buck, Edgar C.

    2012-09-01

    Results for a radiolysis model sensitivity study of radiolytically produced H2O2 are presented as they relate to Spent (or Used) Light Water Reactor uranium oxide (UO2) nuclear fuel (UNF) oxidation in a low oxygen environment. The model builds on previous reaction kinetic studies to represent the radiolytic processes occurring at the nuclear fuel surface. Hydrogen peroxide (H2O2) is the dominant oxidant for spent nuclear fuel in an O2-depleted water environment.

  13. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND No. SAND2016-1893 M

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    SAND No. SAND2016-1893 M TECHNOLOGICAL BENEFITS * Increased efficiency * Reduced cost * Can be implemented on a smaller scale * O 2 separation at ambient temperature & pressure * Produces high purity O 2 METAL-ORGANIC FRAMEWORKS FOR THE SEPARATION OF O 2 FROM AIR Patent Pending Technology Readiness Level:3-4 Basic technological components are integrated to establish that the pieces will work together TECHNOLOGY DESCRIPTION Pure molecular oxygen is important to many industrial processes such

  14. Optically transparent and environmentally durable superhydrophobic coating

    Office of Scientific and Technical Information (OSTI)

    based on functionalized SiO2 nanoparticles (Journal Article) | SciTech Connect Optically transparent and environmentally durable superhydrophobic coating based on functionalized SiO2 nanoparticles Citation Details In-Document Search Title: Optically transparent and environmentally durable superhydrophobic coating based on functionalized SiO2 nanoparticles Optical surfaces such as mirrors and windows that are exposed to outdoor environmental conditions are susceptible to dust buildup and

  15. Investigation of NO2 Oxidation Kinetics and Burning Mode for Medium Duty

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Diesel Particulate: Contrasting O2 and NO2 Oxidation | Department of Energy NO2 Oxidation Kinetics and Burning Mode for Medium Duty Diesel Particulate: Contrasting O2 and NO2 Oxidation Investigation of NO2 Oxidation Kinetics and Burning Mode for Medium Duty Diesel Particulate: Contrasting O2 and NO2 Oxidation Reports on preliminary measurements of particulate reactivity and changes in microstructure upon exposure to NO2, which is often present at significant levels in diesel engine exhaust.

  16. Final Report: Novel ALD-Coated Nanoparticle Anodes for Enhanced Performance Lithium-Ion Batteries

    SciTech Connect (OSTI)

    Groner, Markus

    2009-04-16

    The Phase I effort is described in detail in the Phase I report given below. The key accomplishments of the Phase I project were (1) the demonstration of high stability LiCoO2 cathodes using ALD-coated LiCoO2 particles, as well as on ALD-coated LiCoO2 electrodes and (2) the demonstration of high stability of graphite anodes using ALD-coated graphite electrodes.

  17. Effects of Diesel Exhaust Emissions on Soot Oxidation and DPF...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and O2 emissions found from the thermogravimetric analyzer soot oxidation. PDF icon p-18lee.pdf More Documents & Publications Development of Advanced Diesel Particulate Filtration...

  18. Oxygen A-band Exploitation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ? scatteringreflection diagnostics of media permeated with gas Hi-res O 2 A-band Spectroscopy, I: Cloud products are statistical cross-section density...

  19. Robert E. Blankenship | Photosynthetic Antenna Research Center

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    complexes attached to TiO2 substrates. Lucille P. Markey Distinguished Professor of Arts and Sciences Bio 32311:: Neutron analysis yields insight into bacteria for solar...

  20. LANL: AOT & LANSCE The Pulse June 2010

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    protein, which enables humans to breathe. Hb efficiently transports oxygen (O 2 ) from lungs to tissues. Hb's ability to function properly depends tremendously on binding hydrogen...

  1. Slide 1

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    acid Sn sites in zeolites selectively catalyze glucose epimerization to mannose in methanol and glucose isomerization to fructose in water. Extraframework SnO 2 contains base...

  2. Cray Compiler Peformance on Edison

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    on Edison Cray Compiler Peformance on Edison Cray recommends using the default optimization (-O2) which is equivalent to the higher levels of optimization with other...

  3. Deterministic coupling of delta-doped nitrogen vacancy centers...

    Office of Scientific and Technical Information (OSTI)

    P. ; Hu, Evelyn L., E-mail: ehu@seas.harvard.edu 1 ; Bracher, David O. 2 ; Ohno, ... School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts ...

  4. Investigation of NO2 Oxidation Kinetics and Burning Mode for...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Duty Diesel Particulate: Contrasting O2 and NO2 Oxidation Reports on preliminary measurements of particulate reactivity and changes in microstructure upon exposure to NO2, which...

  5. ARM - Field Campaign - Millimeter-wave Radiometric Arctic Winter...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Westwater Scanning-O2 Radiometer Order Data Racette Millimeter-wave Imaging Radiometer (MIR) Order Data Han Corrected ARM MWR data Order Data Michalsky Rotating Shadowband...

  6. NREL Demonstrates Efficient Solar Water Splitting by Metal Oxide...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    energy sources. Production of O 2 is the only scalable and renewable oxidation that can balance these fuel-forming reduction reactions. However, few materials have the necessary...

  7. Daniel Mieritz | Center for Bio-Inspired Solar Fuel Production

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Daniel Mieritz Graduate student Subtask 5 project: "Transparent, Mesoporous Zr(1-x)Ti(x)O2 Thin Films

  8. Bransen Plasma Asher

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of processing with up to three gases (only one installed) Capabilities: Reactive ion etching with O2 Applications: Resist stripping Substrate cleaningBransen Plasma Asher...

  9. "Title","Creator/Author","Publication Date","OSTI Identifier...

    Office of Scientific and Technical Information (OSTI)

    O2-06CH11357",,"Conference",,,"Conference: APS Colloquium Series, Advanced Photon Source (APS) at Argonne National Laboratory, Argonne, Illinois (United States), presented on March...

  10. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... basal superoxide dismutase (SOD) expression. This data suggests that the regulation of O2?- is located at the crossroads between LDL signaling and cell proliferation. less August

  11. Most Commonly Identified Recommendations

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Renewable Energy Network (EERE): http:... electricity to a certain area of the plant when the ...or install an O2 trim controller system for an automated ...

  12. Impact and Detection of Pyranometer Failure on PV Performance...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ZrO2 Experimental and Modeling Investigation of Radionuclide Interaction and Transport in Representative Geologic Media Brine Migration Experimental Studies for Salt Repositories

  13. Presentation Title

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    o Heavy metal and sodium fast reactor safety - Gen IV research Reactor Technology - "keeping boiling under control" o Thermal hydraulics of Light Water Reactors o 2-phase flow, ...

  14. Binary Cultivation in Photobioreactors - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    cost-efficiently optimizes mass transfer (CO2 delivery and O2 removal) The processes of photosynthesis and photosynthate conversion into a target product are spatially separated...

  15. CX-004010: Categorical Exclusion Determination | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and commercialize two advanced laser based gas sensors for industrial ... measurements of carbon monoxide (CO), carbon dioxide (CO2), oxygen (O2), water (H2O), and gas ...

  16. CDM Projects in Colombia | Open Energy Information

    Open Energy Info (EERE)

    Projects in Colombia Jump to: navigation, search Name CDM Projects in Colombia AgencyCompany Organization C-O2 Sector Energy, Land Topics Finance, Implementation, Market analysis...

  17. Surface Structure Dependence of SO2 Interaction with Ceria Nanocrystals with Well-defined Surface Facets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tumuluri, Uma; Li, Meijun; Cook, Brandon G.; Sumpter, Bobby G.; Dai, Sheng; Wu, Zili

    2015-12-02

    The effects of the surface structure of ceria (CeO2) on the nature, strength, and amount of species resulting from SO2 adsorption were studied using in situ IR and Raman spectroscopies coupled with mass spectrometry, along with first-principles calculations based on density functional theory (DFT). CeO2 nanocrystals with different morphologies, namely, rods (representing a defective structure), cubes (100 facet), and octahedra (111 facet), were used to represent different CeO2 surface structures. IR and Raman spectroscopic studies showed that the structure and binding strength of adsorbed species from SO2 depend on the shape of the CeO2 nanocrystals. SO2 adsorbs mainly as surfacemore » sulfites and sulfates at room temperature on CeO2 rods, cubes, and octahedra that were either oxidatively or reductively pretreated. The formation of sulfites is more evident on CeO2 octahedra, whereas surface sulfates are more prominent on CeO2 rods and cubes. This is explained by the increasing reducibility of the surface oxygen in the order octahedra < cubes < rods. Bulk sulfites are also formed during SO2 adsorption on reduced CeO2 rods. The formation of surface sulfites and sulfates on CeO2 cubes is in good agreement with our DFT results of SO2 interactions with the CeO2(100) surface. CeO2 rods desorb SO2 at higher temperatures than cubes and octahedra nanocrystals, but bulk sulfates are formed on CeO2 rods and cubes after high-temperature desorption whereas only some surface sulfates/sulfites are left on octahedra. This difference is rationalized by the fact that CeO2 rods have the highest surface basicity and largest amount of defects among the three nanocrystals, so they bind and react with SO2 strongly and are the most degraded after SO2 adsorption cycles. The fundamental understanding obtained in this work on the effects of the surface structure and defects on the interaction of SO2 with CeO2 provides insights for the design of more sulfur-resistant CeO2-based catalysts.« less

  18. Attachment O

    Office of Environmental Management (EM)

    O WIPP MINE VENTILATION RATE MONITORING PLAN Waste Isolation Pilot Plant Hazardous Waste Permit May 8, 2012 (This page intentionally blank) Waste Isolation Pilot Plant Hazardous Waste Permit May 8, 2012 PERMIT ATTACHMENT O Page O-1 of 14 1 ATTACHMENT O 2 WIPP MINE VENTILATION RATE MONITORING PLAN 3 TABLE OF CONTENTS 4 O-1 Definitions ....................................................................................................................... 2 5 O-2 Objective

  19. Study of using oxygen-enriched combustion air for locomotive diesel engines

    SciTech Connect (OSTI)

    Poola, R.B.; Sekar, R.; Assanis, D.N.; Cataldi, G.R.

    1996-10-01

    A thermodynamic simulation is used to study effects of O2-enriched intake air on performance and NO emissions of a locomotive diesel engine. Parasitic power of the air separation membrane required to supply the O2-enriched air is also estimated. For a given constraint on peak cylinder pressure, gross and net power output of an engine operating under different levels of O2 enrichment are compared with those obtained when a high-boost turbocharged engine is used. A 4% increase in peak cylinder pressure can result in 13% increase in net engine power when intake air with 28 vol% O2 is used and fuel injection timing retarded by 4 degrees. When the engine is turbocharged to a higher inlet boost, the same increase in peak cylinder pressure can result in only 4% improvement in power. If part of the higher exhaust enthalpies from the O2 enrichment is recovered, the power requirements of the air separator membrane can be met. O2 enrichment with its higher combustion temperatures reduces emissions of particulates and visible smoke but increases NO emissions (by up to 3 times at 26% O2 content). Therefore, exhaust gas after-treatment and heat recovery would be required if the full potential of O2 enrichment for improving the performance of locomotive diesel engines is to be realized.

  20. BPA-2010-02021-FOIA Request

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    . 1 Ir:; WV0 6PA' I O O2o2 * s * o . o Du Schlo g t a f n eldt 900 Washington Street Albert F. 5chlotfeldt * Suite 1020 * PO BoK 570 Direct 360-737-1460 &WelchPLLC Vancouver, WA...

  1. Grafting Sulfated Zirconia on Mesoporous Silica

    SciTech Connect (OSTI)

    Wang, Yong; Lee, Kwan Young; Choi, Saemin; Liu, Jun; Wang, Li Q.; Peden, Charles HF

    2007-06-01

    Sulfated zirconia has received considerable attention as a potential solid acid catalyst in recent years. In this paper, the preparation and properties of acid catalysts obtained by grafting ziconia with atomic precision on MCM-41 mesoporous silica were studied. TEM and potential titration characterizations revealed that ZrO2/MCM-41 with monolayer coverage can be obtained using this grafting technique. Sulfated ZrO2/MCM-41 exhibits improved thermal stability than that of bulk sulfated zirconia, as evidenced by temperature programmed characterizations and XRD analysis. Temperature programmed reaction of isopropanol was used to evaluate the acidity of sulfated ZrO2/MCM-41. It was found that the acid strength of sulfated ZrO2/MCM-41 with monolayer coverage is weaker than bulk sulfated zirconia but stronger than SiO2-Al2O3, a common strong acid catalyst.

  2. Electrodeposited Manganese Oxides on Three-Dimensional Carbon Nanotube Substrate: Supercapacitive Behaviour in Aqueous and Organic Electrolytes

    SciTech Connect (OSTI)

    Nam,K.W.; Yang,X.

    2009-03-01

    Thin amorphous manganese oxide layers with a thickness of 3-5nm are electrodeposited on a carbon nanotube (CNT) film substrate that has a three-dimensional nanoporous structure (denoted asMnO2/CNT electrode). For the purpose of comparison, manganese oxide films are also electrodeposited on a flat Pt-coated Si wafer substrate (denoted as MnO2 film electrode). The pseudocapacitive properties of the MnO2 film and MnO2/CNT electrodes are examined in both aqueous electrolyte (1.0M KCl) and nonaqueousorganic electrolyte (1.0M LiClO4 in propylene carbonate). While both types of electrode showpseudocapacitive behaviour in the aqueous electrolyte, only the MnO2/CNT electrode does so in the organic electrolyte, due to its high oxide/electrolyte interfacial area and improved electron conduction through the CNT substrate. Compared with the MnO2 film electrode, the MnO2/CNT electrode shows a much higher specific capacitance and better high-rate capability, regardless of the electrolyte used.Use of the organic electrolyte results in a ?6 times higher specific energy compared with that obtained with the aqueous electrolyte, while maintaining a similar specific power. The construction of a threedimensional nanoporous network structure consisting of a thin oxide layer on a CNT film substrate at the nm scale and the use of an organic electrolyte are promising approaches to improving the specific energyof supercapacitors.

  3. Distinctive Oxidative Stress Responses to Hydrogen Peroxide in Sulfate Reducing Bacteria Desulfovibrio vulgaris Hildenborough

    SciTech Connect (OSTI)

    Zhou, Aifen; He, Zhili; Redding, A.M.; Mukhopadhyay, Aindrila; Hemme, Christopher L.; Joachimiak, Marcin P.; Bender, Kelly S.; Keasling, Jay D.; Stahl, David A.; Fields, Matthew W.; Hazen, Terry C.; Arkin, Adam P.; Wall, Judy D.; Zhou, Jizhong

    2009-01-01

    Response of Desulfovibrio vulgaris Hildenborough to hydrogen peroxide (H2O2, 1 mM) was investigated with transcriptomic, proteomic and genetic approaches. Microarray data demonstrated that gene expression was extensively affected by H2O2 with the response peaking at 120 min after H2O2 treatment. Genes affected include those involved with energy production, sulfate reduction, ribosomal structure and translation, H2O2 scavenging, posttranslational modification and DNA repair as evidenced by gene coexpression networks generated via a random matrix-theory based approach. Data from this study support the hypothesis that both PerR and Fur play important roles in H2O2-induced oxidative stress response. First, both PerR and Fur regulon genes were significantly up-regulated. Second, predicted PerR regulon genes ahpC and rbr2 were derepressedin Delta PerR and Delta Fur mutants and induction of neither gene was observed in both Delta PerR and Delta Fur when challenged with peroxide, suggesting possible overlap of these regulons. Third, both Delta PerR and Delta Fur appeared to be more tolerant of H2O2 as measured by optical density. Forth, proteomics data suggested de-repression of Fur during the oxidative stress response. In terms of the intracellular enzymatic H2O2 scavenging, gene expression data suggested that Rdl and Rbr2 may play major roles in the detoxification of H2O2. In addition, induction of thioredoxin reductase and thioredoxin appeared to be independent of PerR and Fur. Considering all data together, D. vulgaris employed a distinctive stress resistance mechanism to defend against increased cellular H2O2, and the temporal gene expression changes were consistent with the slowdown of cell growth at the onset of oxidative stress.

  4. High pressure and temperature equation of state and spectroscopic study of

    Office of Scientific and Technical Information (OSTI)

    CeO 2 (Journal Article) | DOE PAGES High pressure and temperature equation of state and spectroscopic study of CeO 2 « Prev Next » Title: High pressure and temperature equation of state and spectroscopic study of CeO 2 Authors: Jacobsen, M. K. ; Velisavljevic, N. ; Dattelbaum, D. M. ; Chellappa, R. S. ; Park, C. Publication Date: 2016-03-17 OSTI Identifier: 1242313 Grant/Contract Number: FG02-94ER14466; AC52-06NA25396; FG02-99ER45775; NA0001974; AC02-06CH11357 Type: Published Article

  5. Evidence for Anisotropic Mechanical Behavior and Nanoscale Chemical

    Office of Scientific and Technical Information (OSTI)

    Heterogeneity in Cycled LiCoO2 (Journal Article) | SciTech Connect Evidence for Anisotropic Mechanical Behavior and Nanoscale Chemical Heterogeneity in Cycled LiCoO2 Citation Details In-Document Search Title: Evidence for Anisotropic Mechanical Behavior and Nanoscale Chemical Heterogeneity in Cycled LiCoO2 Authors: Diercks, D. R. ; Musselman, M. ; Morgenstern, A. ; Wilson, T. ; Kumar, M. ; Smith, K. ; Kawase, M. ; Gorman, B. P. ; Eberhart, M. ; Packard, C. E. Publication Date: 2014-01-01

  6. Microsoft PowerPoint - Datskos_2015_UserProjectHighlight_AngewChemie

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    In this work, we exploit the emulsion droplet8d based growth of silica structures to synthesize a wide range of microstructures made of pure silica (silicon dioxide; SiO2) and hybrid microstructures made of silica and titania (titanium dioxide; TiO2). This approach provides a high degree of control of (1) shape, (2) size, (3) number (less or more), and (4) composition of different parts of the structures. Starting from a spherical particle, we synthesized complex SiO2 structures such as central

  7. 14.11.05 RH Stabilized Si Microwire - JCAP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Stabilized Si Microwire Arrays for Solar-Driven H2O Oxidation Shaner, M. R., Hu, S., Sun, K. & Lewis, N. S. Stabilization of Si microwire arrays for solar-driven H2O oxidation to O2(g) in 1.0 M KOH(aq) using conformal coatings of amorphous TiO2. Energy & Environmental Science 8, 203-207, DOI: 10.1039/c4ee03012e (2015). Scientific Achievement Atomic-layer deposition of TiO2combined with sputtering of NiCrOxoxygen-evolution catalyst on Si microwires yields robust microwire-array

  8. Comparison of silatrane, phosphonic acid, and carboxylic acid functional

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells Authors: Brennan, B.J., Llansola Portoles, M.J., Liddell, P.A., Moore, T.A., Moore, A.L., and Gust, D. Title: Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in

  9. Conference Materials | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Lithium-IonLithium-Oxygen Cells," International Battery Association Meeting, Waikoloa, HI, January 2015. M. K. Y.Chan, "Li-Ion and Li-O2: Exploring Hybrid Electrode...

  10. Sandia National Laboratories: News: Publications: Lab News

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the reaction, since adding water to titanium isopropoxide most often results in a fast reaction and large chunks of TiO2, rather than nanoparticles. "So the trick was to...

  11. Investigation of the electrocatalytic oxygen reduction and evolution reactions in lithium–oxygen batteries

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zheng, Dong; Zhang, Xuran; Qu, Deyu; Yang, Xiao -Qing; Lee, Hung -Sui; Qu, Deyang

    2015-04-21

    Oxygen reduction and oxygen evolution reactions were examined on graphite electrodes with different crystal orientations. The kinetics for the redox couple O2/O2•- are very fast, therefore no catalyst seems necessary to assist the charge transfer process. Apparently, the main source of the overpotential for the O2 reduction reaction is from mass diffusion. Li2O2 becomes soluble in non-aqueous electrolytes in the presence of the tetraethylammonium tetrafluoroborate additive. The soluble B-O22- ions can be oxidized electro-catalytically. The edge orientation of graphite demonstrates superior catalytic activity for the oxidation over basal orientation. The findings reveal an opportunity for recharging Li-air batteries efficiently andmore » a new strategy of developing the catalyst for oxygen evolution reaction.« less

  12. Influence of Topological Spin Fluctuations on Charge Transport

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    eV. The PrincetonALS group performed a detailed investigation of low-energy electronic structure and charge dynamics of the parent cobaltite compound Na0.7CoO2 at ALS Beamlines...

  13. 2-ID-E

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    General Users. For example, in collaboration with G. Woloschak et al, we have looked at TiO2-DNA nanocomposites in mammalian cells 1; B. Twining et al investigate trace elements...

  14. 19O

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    -NMR spectra. 19O deduced , Q. 1999SA75: 19O(-); measured -NQR spectrum in TiO2, MgF2. 19O deduced quadrupole moments. 2001ZH43: 19O(-); measured E, I(, H, t)....

  15. Search results | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    with students building a Gratzel cell, a solar cell employing a layer of nanospheres of TiO2 as the semiconductor and blackberry juice as the light absorber in a non-Si-based solar...

  16. Dyesol Ltd | Open Energy Information

    Open Energy Info (EERE)

    Queanbeyan, New South Wales, Australia Zip: 2620 Product: Manufacturer of dyes and TiO2 for the dye-sensitised PV cell (DSC) market, also has own technology which it is...

  17. 15O

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1993TA28, 1993TAZU: 13O(+), (EC); measured -NMR spectra asymmetry change in TiO2; deduced . 1995GO34: 15O; compiled, reviewed -decay asymmetry data, other aspects;...

  18. Ultrathin nanosheets of CrSiTe3: A semiconducting two-dimensional...

    Office of Scientific and Technical Information (OSTI)

    In this work we for the first time exfoliate the CrSiTe3, a bulk ferromagnetic semiconductor, to mono- and few-layer 2D crystals onto a SiSiO2 substrate. The Raman spectra show ...

  19. Table of Contents: Accelerating Cleanup, Paths to Closure

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    O. OPERATIONS/FIELD OFFICE DATA SUMMARY O.1. OPERATIONS/FIELD OFFICE.......................................................................................................................... 1 O.2. FY 1999 OPERATIONS/FIELD OFFICE FULL COMPLIANCE CASE (IN $000)....................................................... 1 O.3. LIFECYCLE COST DATA................................................................................................................................ 1 O.4. SUPPORT COSTS BREAKOUT

  20. Ammonia formation from NO reaction with surface hydroxyls on...

    Office of Scientific and Technical Information (OSTI)

    insight about the interactions of NO with hydroxyl groups on TiO2(110) . Authors: Kim, Boseong ; Kay, Bruce D. ; Dohnalek, Zdenek ; Kim, Yu Kwon Publication Date:...

  1. Search for: All records | DOE Patents

    Office of Scientific and Technical Information (OSTI)

    Barnabe, Antoine (2) Mason, Thomas O. (2) Poeppelmeier, Kenneth R. (2) Shahriari, Dean Y. (2) Save Results Excel (limit 2000) CSV (limit 5000) XML (limit 5000) Have feedback or ...

  2. Volatility of Vanadia from Vanadia-Based SCR Catalysts under...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Aging Conditions TiO2-supported vanadia (and tungsta) can be stabillized by optimization of the catalyst support PDF icon p-03chapman.pdf More Documents & Publications The...

  3. Adsorption, Desorption, and Displacement Kinetics of H2O and...

    Office of Scientific and Technical Information (OSTI)

    4 H2O to 3 CO2 molecules is needed to displace CO2 from the TiO2(110) surface. Authors: Smith, R. Scott ; Li, Zhenjun ; Chen, Long ; Dohnalek, Zdenek ; Kay, Bruce D. Publication...

  4. Sulfur Resistant Electrodes for Zirconia Oxygen Sensors - Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and is less expensive than platinum.Benefits Increased lifetime, reliability and accuracy Lower cost Applications and IndustriesO2 sensor in any combustion process in which acidic...

  5. Search results | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    cell, a solar cell employing a layer of nanospheres of TiO2 as the semiconductor and blackberry juice as the light absorber in a non-Si-based solar cell. Students are able to build...

  6. Development of Compact Gaseous Sensors with Internal Reference...

    Broader source: Energy.gov (indexed) [DOE]

    Compact sensors have been developed to allow for real-time monitoring of O2 and NOx during combustion. PDF icon deer08singh.pdf More Documents & Publications Compact ...

  7. NREL: Energy Sciences - Materials Science

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and processed under atmospheric conditions. This work includes developing inks for inkjet printing of metals (e.g., Ag, Cu, Ni), metal oxides (e.g., ZnO, SnO2, (Ba,Sr)TiO3),...

  8. Mini Rockets

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and evaluate methods Materials: * 1.0 M Hydrochloric Acid (HCl), approx. 50 mL per H2 generator * 3% Hydrogen Peroxide (H O ), 2 2 approx. 50 mL per oxygen generator * mossy zinc *...

  9. Jun Lu poster presentation 2012

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Figure 3 Typical voltage profile of Li-air battery using PC as electrolyte Figure 4 High-resolution XRD patterns of original SPL carbon and SPL carbon after being loaded with MnO 2 ...

  10. Search results | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    exploration of the relationship between these factors. The unit culminates with students building a Gratzel cell, a solar cell employing a layer of nanospheres of TiO2 as the...

  11. Virtual Oxygen Sensor for Innovative NOx and PM Emission Control...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    along with a virtual intake manifold O2 sensor, show good accuracy with stationary measurements PDF icon deer09traver.pdf More Documents & Publications Simulation and Analysis of...

  12. Search results | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    unknown to the public. One of the first steps in producing silicon is a process called carbon-thermic reduction. Silicon dioxide (SiO2) that is found in beach sand and quartz is...

  13. Influence of Topological Spin Fluctuations on Charge Transport

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    NaxCoO2 (with variable x) is similar to cuprate HTSCs. The parent compounds are Mott insulators, in which a strong electrostatic repulsion blocks charge transport; they...

  14. Pipe diffusion at dislocations in UO2

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of pipe diffusion to the overall O 2 and U 4+ diffusion is also discussed. 2014 Elsevier B.V. All rights reserved. 1. Introduction During its lifetime in-pile nuclear fuel...

  15. Su-Huai Wei - Research Fellow | NREL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Kang, J.; Wei, S.-H.; Zhu, K.; Kim, Y.-H. (2011). "First-principles theory of electrochemical capacitance of nanostructured materials: Pseudocapacitive TiO2 anatase...

  16. Review of the Argonne National Laboratory Alpha-Gamma Hot Cell...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of Smoke Detectors in 212 AGHCF, Rev. 0, 4711 * WCD-11-AGHCF-027, Anchor the Charcoal Filter Housing (NPHE), Rev. 0, 42611 * WCD-11-AGCHF-032, Anchor O2 Analyzer...

  17. Electrolysis | Open Energy Information

    Open Energy Info (EERE)

    energy from a battery, water (H2O) can be dissociated into the diatomic molecules of hydrogen (H2) and oxygen (O2). This process is a good example of the the application of the...

  18. SolarAMP LLC | Open Energy Information

    Open Energy Info (EERE)

    Name: SolarAMP LLC Place: Raleigh, North Carolina Zip: 27615 Product: Developing a PV cell using nanostructured light absorption rods of organic material, and SnO2 (tin oxide) as...

  19. Search results | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    with students building a Gratzel cell, a solar cell employing a layer of nanospheres of TiO2 as the semiconductor and blackberry juice as the light absorber in a non-Si-based...

  20. ECR

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    System 100 ICP180 is an inductively coupled plasma reactive ion etch tool capable of etching wafers up to 6" diameter. This system performs dry etching of Si, SiO2, SiNx and...

  1. ORP-56879

    Office of Scientific and Technical Information (OSTI)

    ... Gas-evolving cold-cap reactions release chemically bonded water and produce NO x , O 2 , ... temperature range unless the mixtures are treated at a wide range of heating rates. ...

  2. MOX Fuel Presentation to Duke Board of Directors

    National Nuclear Security Administration (NNSA)

    PuO 2 with 95% depleted UO 2 - Like LEU fuel pellets, MOX fuel pellets are primarily uranium * Fission power comes primarily from plutonium (Pu 239 ) instead of uranium (U 235 )...

  3. The Fundamental Limitation of Atmospheric Remote Sensing by Dissection...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Remote Sensing by Dissection of Single-Photon State Space, and the Paradigms that Lie Beyond Illustrated with WAIL, O2 A-BandLine Spectroscopy, Etc. Davis, Anthony Los Alamos...

  4. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... We use CO oxidation on gold-covered Bi2Se3 as a prototype example, and show that the robust TSS can significantly enhance the adsorption energy of both CO and O2 molecules,more ...

  5. RAPID/Roadmap/10 (1) | Open Energy Information

    Open Energy Info (EERE)

    description see 40 CFR 230.3(o)(2)). 10.10 to 10.11 - Are There Potential Impacts to Air Quality? Developers must evaluate the impact their project will have on air quality in...

  6. RAPID/Roadmap/10 | Open Energy Information

    Open Energy Info (EERE)

    description see 40 CFR 230.3(o)(2)). 10.10 to 10.11 - Are There Potential Impacts to Air Quality? Developers must evaluate the impact their project will have on air quality in...

  7. DOE-Funded Research at Stanford Sees Results in Reservoir Characteriza...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    effects. To investigate these issues, a nanofluid was created by suspending SiO2 nanoparticles in a liquid solution, and then injecting into a Berea sandstone core. The...

  8. Search results | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    in producing silicon is a process called carbon-thermic reduction. Silicon dioxide (SiO2) that is found in beach sand and quartz is melted down in a caldron at a temperature of...

  9. Spray-on anti-soiling coatings that exhibit high transparency...

    Office of Scientific and Technical Information (OSTI)

    are competitive. We have developed a simple, spray-on coating based on functionalized SiO2 nanoparticles that can easily be applied to surfaces whose application requires high...

  10. Hierarchically Structured Materials for Lithium Batteries (Journal...

    Office of Scientific and Technical Information (OSTI)

    With the increasing demand on devices of high energy densities (>500 Whkg) , new energy storage systems, such as lithium-oxygen (Li-O2) batteries and other emerging systems beyond ...

  11. HIPed Tailored Ceramic Waste Forms for the Immobilization of...

    Office of Scientific and Technical Information (OSTI)

    Experimental data on the immobilization of Tc in titanate ceramics containing up to 40wt% TcO2 are also be presented. Authors: Melody L. Carter ; Martin W. A. Stewart ; Eric R. ...

  12. Microsoft PowerPoint - Das_2015_StaffScienceHighlight_ACSPhotonic...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    obtained in a single step. Moreover, we report USC processing on TiO 2 ITO-coated polyethylene terephthalate (PET) substrates to realize flexible perovskite solar cells with PCE...

  13. Microsoft PowerPoint - Xiao_NanoLett-2013.pptx

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of GaS nanosheet photodetectors made on SiO 2 Si substrates and flexible polyethylene terephthalate (PET) substrates exhibit a photo-responsivity at 254nm up to 4.2 AW...

  14. One Nanocrystal, Many Faces: Connecting the Atomic Surface Structures of

    Office of Science (SC) Website

    CeO2 Nanocrystals to Catalysis | U.S. DOE Office of Science (SC) One Nanocrystal, Many Faces: Connecting the Atomic Surface Structures of CeO2 Nanocrystals to Catalysis Basic Energy Sciences (BES) BES Home About Research Facilities Science Highlights Benefits of BES Funding Opportunities Basic Energy Sciences Advisory Committee (BESAC) Community Resources Contact Information Basic Energy Sciences U.S. Department of Energy SC-22/Germantown Building 1000 Independence Ave., SW Washington, DC

  15. Virtual Oxygen Sensor for Innovative NOx and PM Emission Control

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Technologies | Department of Energy Virtual Oxygen Sensor for Innovative NOx and PM Emission Control Technologies Virtual Oxygen Sensor for Innovative NOx and PM Emission Control Technologies A virtual O2 sensor for the intake manifold of a diesel engine equipped with EGR, along with a virtual intake manifold O2 sensor, show good accuracy with stationary measurements PDF icon deer09_traver.pdf More Documents & Publications Simulation and Analysis of HP/LP EGR for Heavy-Duty Applications

  16. Radiolysis Process Model

    SciTech Connect (OSTI)

    Buck, Edgar C.; Wittman, Richard S.; Skomurski, Frances N.; Cantrell, Kirk J.; McNamara, Bruce K.; Soderquist, Chuck Z.

    2012-07-17

    Assessing the performance of spent (used) nuclear fuel in geological repository requires quantification of time-dependent phenomena that may influence its behavior on a time-scale up to millions of years. A high-level waste repository environment will be a dynamic redox system because of the time-dependent generation of radiolytic oxidants and reductants and the corrosion of Fe-bearing canister materials. One major difference between used fuel and natural analogues, including unirradiated UO2, is the intense radiolytic field. The radiation emitted by used fuel can produce radiolysis products in the presence of water vapor or a thin-film of water (including OH and H radicals, O2-, eaq, H2O2, H2, and O2) that may increase the waste form degradation rate and change radionuclide behavior. H2O2 is the dominant oxidant for spent nuclear fuel in an O2 depleted water environment, the most sensitive parameters have been identified with respect to predictions of a radiolysis model under typical conditions. As compared with the full model with about 100 reactions it was found that only 30-40 of the reactions are required to determine [H2O2] to one part in 105 and to preserve most of the predictions for major species. This allows a systematic approach for model simplification and offers guidance in designing experiments for validation.

  17. Speciation of technetium peroxo complexes in sulfuric acid revisited

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Poineau, Frederic; German, Konstantin E.; Burton-Pye, Benjamin P.; Weck, Philippe F.; Kim, Eunja; Kriyzhovets, Olga; Safonov, Aleksey; Ilin, Viktor; Francesconi, Lynn C.; Sattelberger, Alfred P.; et al

    2014-08-24

    We found that the reaction of Tc(+7) with H2O2 has been studied in H2SO4 and the speciation of technetium performed by UV–visible and 99-Tc NMR spectroscopy. UV–visible measurements show that for H2SO4 ≥ 9 M and H2O2 = 0.17 M, TcO3(OH)(H2O)2 reacts immediately and blue solutions are obtained, while no reaction occurs for H2SO42SO44 - begins to react for H2O2 = 2.12 M and red solutions are obtained. The UV–visible spectra of the red species are identical to the one obtained from the reaction of TcO4 - with H2O2 in HNO3 and consistent with the presence of TcO(O2)2(H2O)(OH). The 99-Tcmore » NMR spectrum of the red solution exhibits a broad signal centered at +5.5 ppm vs TcO4 - and is consistent with the presence of a low symmetry Tc(+7) molecule.« less

  18. Electron-beam-evaporated thin films of hafnium dioxide for fabricating electronic devices

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xiao, Zhigang; Kisslinger, Kim

    2015-06-17

    Thin films of hafnium dioxide (HfO2) are widely used as the gate oxide in fabricating integrated circuits because of their high dielectric constants. In this paper, the authors report the growth of thin films of HfO2 using e-beam evaporation, and the fabrication of complementary metal-oxide semiconductor (CMOS) integrated circuits using this HfO2 thin film as the gate oxide. The authors analyzed the thin films using high-resolution transmission electron microscopy and electron diffraction, thereby demonstrating that the e-beam-evaporation-grown HfO2 film has a polycrystalline structure and forms an excellent interface with silicon. Accordingly, we fabricated 31-stage CMOS ring oscillator to test themore » quality of the HfO2 thin film as the gate oxide, and obtained excellent rail-to-rail oscillation waveforms from it, denoting that the HfO2 thin film functioned very well as the gate oxide.« less

  19. TITANIUM DIOXIDE TRIADS FOR IMPROVED CHARGE-SEPARATION USING CONDUCTIVE POLYMERS

    SciTech Connect (OSTI)

    Cochran, T.M.; Gaylor, T.N.; de la Garza, L.; Rajh, T.

    2009-01-01

    Dye-sensitized solar cells are potentially one of the best solutions to solar energy conversion because of the low cost of required materials and production processes. Titanium dioxide (TiO2) nanoparticulate fi lms are the basis for one of these types of cells, providing large surface area for dye-sensitizer adsorption. Because TiO2 nanoparticulate fi lms develop defects caused by oxygen defi ciency, deep reactive electron traps are formed. With the addition of an enediol ligand, these electron traps are deliberately removed, enhancing the conduction of electrons within the fi lm. In this project, TiO2 nanoparticulate fi lms made by a layer-by-layer dip coating method were modifi ed with 3,4-dihydroxyphenylacetic acid (DOPAC). DOPAC binds to the titanium atoms on the surface of the nanoparticles, restoring their octahedral geometry. This restructuring of the surface shifts the spectral properties of the TiO2 to the visible spectrum and improves the separation of charges which is observed using photoelectrochemistry. Furthermore, DOPAC enables the electronic attachment of other molecules to the surface of TiO2 fi lms, such as the conductive polymer polyaniline base. This conductive polymer provides an extended separation of charges which increases photocurrent production by forming a triad with the TiO2 semiconductor through the 3,4-dihydroxyphenylacetic acid linker. The photocurrent increases due to the donor properties of the conductive polymer thereby decreasing charge pair recombination.

  20. Performance of Lanthanum Strontium Manganite Electrodes at High Pressure

    SciTech Connect (OSTI)

    Thomsen, Edwin C.; Coffey, Greg W.; Pederson, Larry R.; Marina, Olga A.

    2009-06-15

    The high-pressure performance of lanthanum strontium manganite (LSM), LSM-zirconia, and LSM/ceria composite electrodes was studied by impedance spectroscopy and dc methods. Electrode resistances decreased in proportion to P(O2)1/2 for the LSM electrode in both cathodic and anodic directions to at least 100 atm, a decrease that was attributed to dissociative oxygen adsorption, surface diffusion, and related phenomena. For the LSM-20/zirconia composite electrode, resistances decreased in proportion to P(O2)1/4 across the entire pressure range considered. Two principal features appeared in the impedance spectra, one that showed a P(O2)1/4 dependence attributed to charge transfer reactions, and one that was nearly pressure-independent, possibly due to transport in the zirconia portion of the composite. For the LSM-20/ceria composite electrode, resistances decreased as P(O2)0.3-0.4 at high pressure, depending on temperature. Two features appeared in the impedance spectra: one at low to intermediate frequency having a P(O2)1/2 dependence and one at high frequency having a P(O2)1/4 dependence. These features are attributed to dissociative oxygen adsorption and to charge transfer reactions, respectively. Results suggest that cathodic losses can be substantially lowered by operation of solid oxide fuel cells at greater than ambient pressure.