National Library of Energy BETA

Sample records for atmospheric oxygen o2

  1. Enhanced oxygen evolution activity of IrO2 and RuO2 (100) surfaces...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Enhanced oxygen evolution activity of IrO2 and RuO2 (100) surfaces Citation Details In-Document Search ... Here we report that the (100) surface of IrO2 and RuO2 is ...

  2. 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.

  3. Characterization of oxygen and titanium diffusion at the anatase TiO2(001) surface

    SciTech Connect (OSTI)

    Herman, Gregory S.; Zehr, Robert T.; Henderson, Michael A.

    2013-06-01

    The diffusion of intrinsic defects in a single crystal anatase TiO2(001) film was explored by isotopic labeling and static secondary ion mass spectrometry. Using both 46Ti and 18O as isotopic labels, we show that the anatase surface responds to redox imbalances by diffusion of both Ti and O into the bulk under vacuum reduction and (at least) Ti from the bulk to the surface during oxidation. The diffusion of Ti between the bulk and surface in anatase TiO2(001) closely resembles what was observed in the literature for the rutile TiO2(110) surface, however the latter is not known to have oxygen diffusion between the bulk and surface under typical ultrahigh vacuum conditions. We speculate that the open lattice of the anatase bulk structure may facilitate independent diffusion of both point defects (Ti interstitials and O vacancies) or concerted diffusion of "TiO" subunits. The authors gratefully acknowledge S.A. Chambers of Pacific Northwest National Laboratory (PNNL) for providing the anatase samples. This research was supported by the U.S. Department of Energy (DOE) Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, the Office of Naval Research Contract Number 200CAR262, and the Oregon Nanoscience and Microtechnologies Institute. PNNL is operated for the U.S. DOE by Battelle under Contract Number DE05-AC76RL0 1830. The research was performed in the William R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility funded by the U.S. DOE Office of Biological and Environmental Research.

  4. Role of Cu-Ion Doping in Cu-α-MnO2 Nanowire Electrocatalysts for the Oxygen Reduction Reaction

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

    Davis, Danae J.; Lambert, Timothy N.; Vigil, Julian A.; Rodriguez, Mark A.; Brumbach, Michael T.; Coker, Eric N.; Limmer, Steven J.

    2014-07-09

    The role of Cu-ion doping in α-MnO2 electrocatalysts for the oxygen reduction reaction in alkaline electrolyte was investigated. Copper doped α-MnO2 nanowires (Cu-α-MnO2) were prepared with varying amounts of Cu2+ using a solvothermal method. The electrocatalytic dataindicates that Cu-α-MnO2 nanowires have higher terminal current densities, enhanced kinetic rate constants, and improved charge transfer resistances that trend with Cu-content, exceeding values attained by α-MnO2 alone. The observed improvement in catalytic behavior correlates with an increase in Mn3+ content for the Cu-α-MnO2 nanowires. The Mn3+/Mn4+ couple is themediator for the rate-limiting redox driven O2-/OH- exchange. It is proposed that O2 adsorbs viaanmore » axial site (the eg orbital on the Mn3+ d4 ion) at the surface, or at edge defects, of the nanowireand that the increase in covalent nature of the nanowire with Cu-ion doping leads to stabilization of O2 adsorbates and faster rates of reduction. This work is applicable to other manganese oxide electrocatalysts and shows for the first time there is a correlation for manganese oxides between electrocatalytic activity for the ORR in alkaline electrolyte and an increase in Mn3+ character of the oxide.« less

  5. Oxygen detected in atmosphere of Saturn's moon Dione

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

    Oxygen detected in atmosphere of Saturn's moon Dione Oxygen detected in atmosphere of Saturn's moon Dione Scientists and an international research team have announced discovery of molecular oxygen ions in the upper-most atmosphere of Dione. March 3, 2012 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to plasma physics

  6. Oxygen self-diffusion in ThO2 under pressure: Connecting point defect parameters with bulk properties

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

    Cooper, Michael William D.; Fitzpatrick, M. E.; Tsoukalas, L. H.; Chroneos, A.

    2016-06-06

    ThO2 is a candidate material for use in nuclear fuel applications and as such it is important to investigate its materials properties over a range of temperatures and pressures. In the present study molecular dynamics calculations are used to calculate elastic and expansivity data. These are used in the framework of a thermodynamic model, the cBΩ model, to calculate the oxygen self-diffusion coefficient in ThO2 over a range of pressures (–10–10 GPa) and temperatures (300–1900 K). As a result, increasing the hydrostatic pressure leads to a significant reduction in oxygen self-diffusion. Conversely, negative hydrostatic pressure significantly enhances oxygen self-diffusion.

  7. 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.

  8. 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

  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, 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

  10. Theoretical investigation of thermodynamic stability and mobility of the oxygen vacancy in ThO2 –UO2 solid solutions

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

    Liu, B.; Aidhy, D. S.; Zhang, Y.; Weber, W. J.

    2014-10-16

    The thermodynamic stability and the migration energy barriers of oxygen vacancies in ThO2 –UO2 solid solutions are investigated by density functional theory calculations. In pure ThO2, the formation energy of oxygen vacancy is 7.58 eV and 1.46 eV under O rich and O poor conditions, respectively, while its migration energy barrier is 1.97 eV. The addition of UO2 into ThO2 significantly decreases the energetics of formation and migration of the oxygen vacancy. Among the range of UO2-ThO2 solid solutions studied in this work, UO2 exhibits the lowest formation energy (5.99 eV and -0.13 eV under O rich and O poormore » conditions, respectively) and Th0.25U0.75O2 exhibits the lowest migration energy barrier (~ 1 eV). Moreover, by considering chemical potential, the phase diagram of oxygen vacancy as a function of both temperature and oxygen partial pressure is shown, which could help to gain experimental control over oxygen vacancy concentration.« less

  11. 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

  12. 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.

  13. 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.

  14. Quenching of electron transfer reactions through coadsorption: A study of oxygen photodesorption from TiO2(110)

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

    Petrik, Nikolay G.; Kimmel, Greg A.; Shen, Mingmin; Henderson, Michael A.

    2016-01-11

    Using temperature programmed desorption (TPD) and photon-stimulated desorption (PSD), we show that coadsorbates of varying binding energies on the rutile TiO2(110) surface exert a commensurate inhibiting influence on the hole-mediated photodesorption of adsorbed O2. A variety of coadsorbates (Ar, Kr, Xe, N2, CO, CO2, CH4, N2O, acetone, methanol or water) were shown to quench O2 photoactivity, with the extent correlating with the coadsorbate's gas phase basicity, which in turn determines the strength of the coadsorbate–Ti4+ bond. Coadsorbed rare gases inhibited the photodesorption of O2 by ~ 10–25%, whereas strongly bound species (water, methanol, and acetone) nearly completely inhibited O2 PSD.more » We suggest that coadsorption of these molecules inhibit the arrival probability of holes to the surface. Band-bending effects, which vary with the extent of charge transfer between the coadsorbate and the TiO2(110) surface, are not expected to be significant in the cases of the rare gases and physisorbed species. Furthermore, these results indicate that neutral coadsorbates can exert a significant influence on charge transfer events by altering the interfacial dipole in the vicinity of the target molecule.« less

  15. Abiotic ozone and oxygen in atmospheres similar to prebiotic Earth

    SciTech Connect (OSTI)

    Domagal-Goldman, Shawn D.; Segura, Antígona; Claire, Mark W.; Robinson, Tyler D.; Meadows, Victoria S.

    2014-09-10

    The search for life on planets outside our solar system will use spectroscopic identification of atmospheric biosignatures. The most robust remotely detectable potential biosignature is considered to be the detection of oxygen (O{sub 2}) or ozone (O{sub 3}) simultaneous to methane (CH{sub 4}) at levels indicating fluxes from the planetary surface in excess of those that could be produced abiotically. Here we use an altitude-dependent photochemical model with the enhanced lower boundary conditions necessary to carefully explore abiotic O{sub 2} and O{sub 3} production on lifeless planets with a wide variety of volcanic gas fluxes and stellar energy distributions. On some of these worlds, we predict limited O{sub 2} and O{sub 3} buildup, caused by fast chemical production of these gases. This results in detectable abiotic O{sub 3} and CH{sub 4} features in the UV-visible, but no detectable abiotic O{sub 2} features. Thus, simultaneous detection of O{sub 3} and CH{sub 4} by a UV-visible mission is not a strong biosignature without proper contextual information. Discrimination between biological and abiotic sources of O{sub 2} and O{sub 3} is possible through analysis of the stellar and atmospheric context—particularly redox state and O atom inventory—of the planet in question. Specifically, understanding the spectral characteristics of the star and obtaining a broad wavelength range for planetary spectra should allow more robust identification of false positives for life. This highlights the importance of wide spectral coverage for future exoplanet characterization missions. Specifically, discrimination between true and false positives may require spectral observations that extend into infrared wavelengths and provide contextual information on the planet's atmospheric chemistry.

  16. Influence of Microstructure and Surface Activation of Dual-Phase Membrane Ce 0.8 Gd 0.2 O 2-δ -FeCo 2 O 4 on Oxygen Permeation

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

    Ramasamy, Madhumidha; Baumann, Stefan; Palisaitis, Justinas; Schulze-Küppers, Falk; Balaguer, Maria; Kim, Daejin; Meulenberg, Wilhelm A.; Mayer, Jochim; Bhave, Ramesh; Guillon, Olivier; et al

    2015-09-24

    In dual-phase oxygen transport membranes we noticed that there is fast-growing interest in research for oxyfuel combustion process application. One such potential candidate is CGO-FCO (60wt% Ce0.8Gd0.2O2-δ-40wt% FeCo2O4) identified to provide good oxygen permeation flux with substantial stability in harsh atmosphere. Dense CGO-FCO membranes of 1mm thickness were fabricated by sintering dry pellets pressed from powders synthesized by one-pot method (modified Pechini process) at 1200 degrees C for 10h. Microstructure analysis indicates presence of a third orthorhombic perovskite phase in the sintered composite. We also identified that the spinel phase tends to form an oxygen deficient phase at the grainmore » boundary of spinel and CGO phases. Surface exchange limitation of the membranes was overcome by La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) porous layer coating over the composite. Moreover, the oxygen permeation flux of the CGO-FCO screen printed with a porous layer of 10mthick LSCF is 0.11mL/cm2 per minute at 850 degrees C with argon as sweep and air as feed gas at the rates of 50 and 250mL/min.« less

  17. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

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

    Franz, Robert; Polcik, Peter; Anders, André

    2015-06-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected tomore » collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.« less

  18. 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.

  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. Oxygen detected in atmosphere of Saturn's moon Dione

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

    is the possibility that on a moon with subsurface water, such as Jupiter's moon Europa, molecular oxygen could combine with carbon in subsurface lakes to form the building...

  1. How a weird Mars rock may be solid proof of an ancient oxygen atmosphere

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

    Weird Mars rock may be solid proof of ancient oxygen atmosphere How a weird Mars rock may be solid proof of an ancient oxygen atmosphere When researchers found a compound that shouldn't have been there, it revealed a missing piece of Mars' history. August 1, 2016 How a weird Mars rock may be solid proof of an ancient oxygen atmosphere The Gale Crater captured by the Thermal Emission Imaging System (THEMIS) on NASA's Mars Odyssey orbiter. CREDIT: NASA/JPL-Caltech/Arizona State University How a

  2. Discovery of oxygen in atmosphere could mean life for Saturn's moon Dione

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

    Discovery of oxygen in atmosphere could mean life for Saturn's moon Dione Discovery of oxygen in atmosphere could mean life for Saturn's moon Dione Discovery could mean ingredients for life are abundant on icy space bodies. March 5, 2012 Curiosity rover bears three LANL technologies Inside Titan: This artist's concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA's Cassini spacecraft. Scientists have been trying to determine what is under Titan's

  3. MONTE CARLO SIMULATION OF METASTABLE OXYGEN PHOTOCHEMISTRY IN COMETARY ATMOSPHERES

    SciTech Connect (OSTI)

    Bisikalo, D. V.; Shematovich, V. I. [Institute of Astronomy of the Russian Academy of Sciences, Moscow (Russian Federation); Grard, J.-C.; Hubert, B. [Laboratory for Planetary and Atmospheric Physics (LPAP), University of Lige, Lige (Belgium); Jehin, E.; Decock, A. [Origines Cosmologiques et Astrophysiques (ORCA), University of Lige (Belgium); Hutsemkers, D. [Extragalactic Astrophysics and Space Observations (EASO), University of Lige (Belgium); Manfroid, J., E-mail: B.Hubert@ulg.ac.be [High Energy Astrophysics Group (GAPHE), University of Lige (Belgium)

    2015-01-01

    Cometary atmospheres are produced by the outgassing of material, mainly H{sub 2}O, CO, and CO{sub 2} from the nucleus of the comet under the energy input from the Sun. Subsequent photochemical processes lead to the production of other species generally absent from the nucleus, such as OH. Although all comets are different, they all have a highly rarefied atmosphere, which is an ideal environment for nonthermal photochemical processes to take place and influence the detailed state of the atmosphere. We develop a Monte Carlo model of the coma photochemistry. We compute the energy distribution functions (EDF) of the metastable O({sup 1}D) and O({sup 1}S) species and obtain the red (630nm) and green (557.7nm) spectral line shapes of the full coma, consistent with the computed EDFs and the expansion velocity. We show that both species have a severely non-Maxwellian EDF, that results in broad spectral lines and the suprathermal broadening dominates due to the expansion motion. We apply our model to the atmosphere of comet C/1996 B2 (Hyakutake) and 103P/Hartley 2. The computed width of the green line, expressed in terms of speed, is lower than that of the red line. This result is comparable to previous theoretical analyses, but in disagreement with observations. We explain that the spectral line shape does not only depend on the exothermicity of the photochemical production mechanisms, but also on thermalization, due to elastic collisions, reducing the width of the emission line coming from the O({sup 1}D) level, which has a longer lifetime.

  4. First-principles study of the stability of free-standing germanene in oxygen atmosphere

    SciTech Connect (OSTI)

    Liu, G.; Liu, S. B. Song, H. Y.; Xu, B.; Ouyang, C. Y.

    2015-09-28

    The O{sub 2} dissociation and O atoms adsorption on free-standing germanene are studied by using first-principles calculations in this paper. Compared with the extremely active silicene in oxygen atmosphere, germanene is found to be less active due to an energy barrier for dissociation of about 0.57 eV. Moreover, the dissociated oxygen atom follows two opposite migration pathways on the germanene surface, which is quite different from the case of silicene. Furthermore, the migration and desorption of O atoms at room temperature are relatively difficult due to the strong Ge-O bonding, resulting in the formation of germanium oxides. Our results reveal the interplay between germanene and O{sub 2} and suggest the enhanced stability of germanene in oxygen atmosphere compared with silicene.

  5. Influence of oxygen traces on an atmospheric-pressure radio-frequency capacitive argon plasma discharge

    SciTech Connect (OSTI)

    Li Shouzhe; Wu Qi; Yan Wen; Wang Dezhen [Key Laboratory of Materials Modification by Laser, Ion, Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China) and School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Uhm, Han S. [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 137-701 (Korea, Republic of)

    2011-10-15

    An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O{sub 2}/Ar. With respect to the influence of oxygen component when diluted into argon plasma discharge on the discharge characteristics, the measurements of the electrical parameters (impedance, phase angle, resistance, and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy (OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.

  6. 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.

  7. Researchers Directly Observe Oxygen Signature in the Oxygen-evolving

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

    Complex of Photosynthesis Researchers Directly Observe Oxygen Signature in the Oxygen-evolving Complex of Photosynthesis Arguably the most important chemical reaction on earth is the photosynthetic splitting of water to molecular oxygen by the Mn-containing oxygen-evolving complex (Mn-OEC) in the protein known as photosystem II (PSII). It is this reaction which has, over the course of some 3.8 billion years, gradually filled our atmosphere with O2 and consequently enabled and sustained the

  8. A dominant role of oxygen additive on cold atmospheric-pressure He + O{sub 2} plasmas

    SciTech Connect (OSTI)

    Yang, Aijun; Liu, Dingxin E-mail: xhw@mail.xjtu.edu.cn; Rong, Mingzhe; Wang, Xiaohua E-mail: xhw@mail.xjtu.edu.cn; Kong, Michael G.

    2014-08-15

    We present in this paper how oxygen additive impacts on the cold atmospheric-pressure helium plasmas by means of a one-dimensional fluid model. For the oxygen concentration [O{sub 2}]?>??0.1%, the influence of oxygen on the electron characteristics and the power dissipation becomes important, e.g., the electron density, the electron temperature in sheath, the electron-coupling power, and the sheath width decreasing by 1.6 to 16 folds with a two-log increase in [O{sub 2}] from 0.1% to 10%. Also the discharge mode evolves from the ? mode to the ? mode. The reactive oxygen species are found to peak in the narrow range of [O{sub 2}]?=?0.4%0.9% in the plasmas, similar to their power-coupling values. This applies to their wall fluxes except for those of O* and O{sub 2}{sup ?}. These two species have very short lifetimes, thus only when generated in boundary layers within several micrometers next to the electrode can contribute to the fluxes. The dominant reactive oxygen species and the corresponding main reactions are schematically presented, and their relations are quantified for selected applications.

  9. Analysis by oxygen atom number density measurement of high-speed hydrophilic treatment of polyimide using atmospheric pressure microwave plasma

    SciTech Connect (OSTI)

    Ono, S.

    2015-03-30

    This paper describes the fundamental experimental data of the plasma surface modification of the polyimide using atmospheric pressure microwave plasma source. The experimental results were discussed from the point of view of the radicals behavior, which significantly affects the modification mechanism. The purpose of the study is to examine how the value of the oxygen atom density will affect the hydrophilic treatment in the upstream region of the plasma where gas temperature is very high. The surface modification experiments were performed by setting the polyimide film sample in the downstream region of the plasma. The degree of the modification was measured by a water contact angle measurement. The water contact angle decreased less than 30 degrees within 1 second treatment time in the upstream region. Very high speed modification was observed. The reason of this high speed modification seems that the high density radical which contributes the surface modification exist in the upstream region of the plasma. This tendency is supposed to the measured relatively high electron density (~10{sup 15}cm{sup ?3}) at the center of the plasma. We used the electric heating catalytic probe method for oxygen radical measurement. An absolute value of oxygen radical density was determined by catalytic probe measurement and the results show that ~10{sup 15}cm{sup ?3} of the oxygen radical density in the upstream region and decreases toward downstream region. The experimental results of the relation of the oxygen radical density and hydrophilic modification of polyimide was discussed.

  10. Commercial demonstration of atmospheric medium BTU fuel gas production from biomass without oxygen the Burlington, Vermont Project

    SciTech Connect (OSTI)

    Rohrer, J.W.

    1995-12-31

    The first U.S. demonstration of a gas turbine operating on fuel gas produced by the thermal gasification of biomass occurred at Battelle Columbus Labs (BCL) during 1994 using their high throughput indirect medium Btu gasification Process Research Unit (PRU). Zurn/NEPCO was retained to build a commercial scale gas plant utilizing this technology. This plant will have a throughput rating of 8 to 12 dry tons per hour. During a subsequent phase of the Burlington project, this fuel gas will be utilized in a commercial scale gas turbine. It is felt that this process holds unique promise for economically converting a wide variety of biomass feedstocks efficiently into both a medium Btu (500 Btu/scf) gas turbine and IC engine quality fuel gas that can be burned in engines without modification, derating or efficiency loss. Others are currently demonstrating sub-commercial scale thermal biomass gasification processes for turbine gas, utilizing both atmospheric and pressurized air and oxygen-blown fluid bed processes. While some of these approaches hold merit for coal, there is significant question as to whether they will prove economically viable in biomass facilities which are typically scale limited by fuel availability and transportation logistics below 60 MW. Atmospheric air-blown technologies suffer from large sensible heat loss, high gas volume and cleaning cost, huge gas compressor power consumption and engine deratings. Pressurized units and/or oxygen-blown gas plants are extremely expensive for plant scales below 250 MW. The FERCO/BCL process shows great promise for overcoming the above limitations by utilizing an extremely high throughout circulation fluid bed (CFB) gasifier, in which biomass is fully devolitalized with hot sand from a CFB char combustor. The fuel gas can be cooled and cleaned by a conventional scrubbing system. Fuel gas compressor power consumption is reduced 3 to 4 fold verses low Btu biomass gas.

  11. 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.

  12. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    SciTech Connect (OSTI)

    Franz, Robert; Polcik, Peter; Anders, Andr

    2015-06-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.

  13. 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

  14. 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]

  15. Virtual Oxygen Sensor for Innovative NOx and PM Emission Control...

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

    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 ...

  16. Absolute atomic oxygen and nitrogen densities in radio-frequency driven atmospheric pressure cold plasmas: Synchrotron vacuum ultra-violet high-resolution Fourier-transform absorption measurements

    SciTech Connect (OSTI)

    Niemi, K.; O'Connell, D.; Gans, T.; Oliveira, N. de; Joyeux, D.; Nahon, L.; Booth, J. P.

    2013-07-15

    Reactive atomic species play a key role in emerging cold atmospheric pressure plasma applications, in particular, in plasma medicine. Absolute densities of atomic oxygen and atomic nitrogen were measured in a radio-frequency driven non-equilibrium plasma operated at atmospheric pressure using vacuum ultra-violet (VUV) absorption spectroscopy. The experiment was conducted on the DESIRS synchrotron beamline using a unique VUV Fourier-transform spectrometer. Measurements were carried out in plasmas operated in helium with air-like N{sub 2}/O{sub 2} (4:1) admixtures. A maximum in the O-atom concentration of (9.1 {+-} 0.7) Multiplication-Sign 10{sup 20} m{sup -3} was found at admixtures of 0.35 vol. %, while the N-atom concentration exhibits a maximum of (5.7 {+-} 0.4) Multiplication-Sign 10{sup 19} m{sup -3} at 0.1 vol. %.

  17. Artificial oxygen transport protein

    DOE Patents [OSTI]

    Dutton, P. Leslie

    2014-09-30

    This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

  18. 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.

  19. Melt processing of the Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub y] superconductor in oxygen and argon atmospheres

    SciTech Connect (OSTI)

    Holesinger, T.G.; Miller, D.J. ); Chumbley, L.S. )

    1992-08-01

    Solidification and subsequent annealing of Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub y] (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O[sub 2] and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi[sub 2]Sr[sub 3-x]Ca[sub x]O[sub y] and Cu[sub 2]O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi[sub 2.15]Sr[sub 2]Ca[sub 0.85]Cu[sub 2]O[sub y].

  20. Melt processing of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor in oxygen and argon atmospheres

    SciTech Connect (OSTI)

    Holesinger, T.G.; Miller, D.J.; Chumbley, L.S.

    1992-08-01

    Solidification and subsequent annealing of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O{sub 2} and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi{sub 2}Sr{sub 3-x}Ca{sub x}O{sub y} and Cu{sub 2}O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi{sub 2.15}Sr{sub 2}Ca{sub 0.85}Cu{sub 2}O{sub y}.

  1. 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 C–C 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 C2–C4 product distributions.

  2. 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.

  3. 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.

  4. Advanced O2 Separation System Integration for Conceptual Design...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Advanced O2 Separation System Integration for Conceptual Design of Supercritical O2-Based PC Boiler Citation Details In-Document Search Title: Advanced O2 ...

  5. 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

  6. The Mechanisms of Oxygen Reduction and Evolution Reactions in Nonaqueous Lithium-Oxygen Batteries

    SciTech Connect (OSTI)

    Cao, Ruiguo; Walter, Eric D.; Xu, Wu; Nasybulin, Eduard N.; Bhattacharya, Priyanka; Bowden, Mark E.; Engelhard, Mark H.; Zhang, Jiguang

    2014-09-01

    The oxygen reduction/evolution reaction (ORR/OER) mechanisms in nonaqueous Li-O2 batteries have been investigated by using electron paramagnetic resonance spectroscopy in this work. We identified the superoxide radical anion (O2•-) as an intermediate in the ORR process using 5,5-dimethyl-pyrroline N-oxide as a spin trap, while no O2•- in OER was detected during the charge process. These findings provide insightful understanding on the fundamental oxygen reaction mechanisms in rechargeable nonaqueous Li-O2 batteries.

  7. 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.

  8. Investigation on the Charging Process of Li2O2-Based Air Electrodes in Li-O2 Batteries with Organic Carbonate Electrolytes

    SciTech Connect (OSTI)

    Xu, Wu; Viswanathan, Vilayanur V.; Wang, Deyu; Towne, Silas A.; Xiao, Jie; Nie, Zimin; Hu, Dehong; Zhang, Jiguang

    2011-04-15

    The charge processes of Li-O2 batteries were investigated by analyzing the gas evolution by in situ gas chromatography-mass spectroscopy (GC/MS) technique. The mixture of Li2O2/Fe3O4/Super P carbon/polyvinylidene fluoride (PVDF) was used as the starting air electrode material and 1M LiTFSI in carbonate-based solvents was used as electrolyte. It was found that Li2O2 is reactive to 1-methyl-2-pyrrolidinone and PVDF binder used in the electrode preparation. During the 1st charge (up to 4.6 V), O2 was the main component in the gases released. The amount of O2 measured by GC/MS was consistent with the amount of Li2O2 decomposed in the electrochemical process as measured by the charge capacity, indicative of the good chargeability of Li2O2. However, after the cell was discharged to 2.0 V in O2 atmosphere and re-charged to ~ 4.6 V in the second cycle, CO2 was dominant in the released gases. Further analysis of the discharged air electrode by X-ray diffraction and Fourier transform infrared spectroscopy indicated that lithium-containing carbonate species (lithium alkyl carbonate and/or Li2CO3) were the main reaction products. Therefore, compatible electrolyte and electrodes as well as the electrode preparation procedures need to be developed for long term operation of rechargeable Li-O2 or Li-air batteries.

  9. Cation and Vacancy Disorder in U1-yNdyO2.00-X Alloys

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

    Barabash, Rozaliya I.; Voit, Stewart L.; Aidhy, Dilpuneet S.; Lee, Seung Min; Knight, Travis W.; Sprouster, David J.; Ecker, Lynne E.

    2015-09-14

    In this study, the intermixing and clustering of U/Nd, O, and vacancies were studied by both laboratory and synchrotron-based x-ray diffraction in U1-yNdyO2-X alloys. It was found that an increased holding time at the high experimental temperature during initial alloy preparation results in a lower disorder of the Nd distribution in the alloys. Adjustment of the oxygen concentration in the U1-yNdyO2-X alloys with different Nd concentrations was accompanied by the formation of vacancies on the oxygen sublattice and a nanocrystalline component. The lattice parameters in the U1-yNdyO2-X alloys were also found to deviate significantly from Vegard's law when the Ndmore » concentration was high (53%) and decreased with increasing oxygen concentration. Such changes indicate the formation of large vacancy concentrations during oxygen adjustment at these high temperatures. Finally, the change in the vacancy concentration after the oxygen adjustment was estimated relative to Nd concentration and oxygen stoichiometry.« less

  10. Advanced O2 Separation System Integration for Conceptual Design...

    Office of Scientific and Technical Information (OSTI)

    System Integration for Conceptual Design of Supercritical O2-Based PC Boiler Citation Details In-Document Search Title: Advanced O2 Separation System Integration for ...

  11. 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:...

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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.

  18. Oxygen analyzer

    DOE Patents [OSTI]

    Benner, William H.

    1986-01-01

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N.sub.2), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable oxygen obtained by decomposing the sample at 1135.degree. C., or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135.degree. C. as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N.sub.2, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  19. Conceptual Design of Supercritical O2-Based PC Boiler (Technical...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Conceptual Design of Supercritical O2-Based PC Boiler Citation Details In-Document Search Title: Conceptual Design of Supercritical O2-Based PC Boiler No abstract ...

  20. Conceptual Design of Supercritical O2-Based PC Boiler (Technical...

    Office of Scientific and Technical Information (OSTI)

    Conceptual Design of Supercritical O2-Based PC Boiler Citation Details In-Document Search Title: Conceptual Design of Supercritical O2-Based PC Boiler You are accessing a ...

  1. 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) .

  2. Oxygen analyzer

    DOE Patents [OSTI]

    Benner, W.H.

    1984-05-08

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N/sub 2/), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable obtained by decomposing the sample at 1135/sup 0/C, or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135/sup 0/C as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N/sub 2/, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  3. Fundamental Understanding of the Interaction of Acid Gases with CeO2 : From Surface Science to Practical Catalysis

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

    Tumuluri, Uma; Rother, Gernot; Wu, Zili

    2016-03-21

    Acid gases including CO2, SO2, and NOx are ubiquitous in large-scale energy applications including heterogeneous catalysis. The adverse environmental and health effects of these acid gases have resulted in high interest in the research and development of technologies to remove or convert these acid gases. The main challenge for the development of these technologies is to develop catalysts that are highly efficient, stable, and cost-effective, and many catalysts have been reported in this regard. CeO2 and CeO2-based catalysts have gained prominence in the removal and conversion of CO2, SO2, and NOx because of their structural robustness and redox and acid–basemore » properties. In this article, we provide a brief overview of the application of CeO2 and CeO2-based catalysts for the removal of CO2, SO2, and NOx gases with an emphasis on the fundamental understanding of the interactions of these acid gases with CeO2. The studies summarized in this review range from surface science using single crystals and thin films with precise crystallographic planes to practical catalysis applications of nanocrystalline and polycrystalline CeO2 materials with defects and dopants. After an introduction to the properties of CeO2 surfaces, their catalytic properties for conversions of different acid gases are reviewed and discussed. Lastly, we find that the surface atomic structure, oxygen vacancies, and surface acid–base properties of CeO2 play vital roles in the surface chemistry and structure evolution during the interactions of acid gases with CeO2 and CeO2-based catalysts.« less

  4. 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

  5. Atmospheric Chemistry

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

    chemistry Atmospheric Chemistry Atmospheric Chemistry is the study of the composition of the atmosphere, the sources and fates of gases and particles in air, and changes induced by ...

  6. 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

  7. 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

  8. 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.

  9. Temperature-programmed desorption study of NO reactions on rutile TiO2(110)-1×1

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

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

    2016-02-24

    In this study, systematic temperature-programmed desorption (TPD) studies of NO adsorption and reactions on rutile TiO2(110)-1 × 1 surface reveal several distinct reaction channels in a temperature range of 50–500 K. NO readily reacts on TiO2(110) to form N2O, which desorbs between 50 and 200 K (LT N2O channels), which leaves the TiO2 surface populated with adsorbed oxygen atoms (Oa) as a by-product of N2O formation. In addition, we observe simultaneous desorption peaks of NO and N2O at 270 K (HT1 N2O) and 400 K (HT2 N2O), respectively, both of which are attributed to reaction-limited processes. No N-derived reaction productmore » desorbs from TiO2(110) surface above 500 K or higher, while the surface may be populated with Oa's and oxidized products such as NO2 and NO3. The adsorbate-free TiO2 surface with oxygen vacancies can be regenerated by prolonged annealing at 850 K or higher. Detailed analysis of the three N2O desorption yields reveals that the surface species for the HT channels are likely to be various forms of NO dimers.« less

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

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

    Calaza, Florencia C.; Chen, Tsung -Liang; Mullins, David R.; Xu, Ye; Steven H. Overbury

    2015-05-02

    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 CeO2 surface, 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 acidmore » desorb. Furthermore, 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.« less

  11. 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.

  12. Economic Analysis for Conceptual Design of Supercritical O2-Based...

    Office of Scientific and Technical Information (OSTI)

    Economic Analysis for Conceptual Design of Supercritical O2-Based PC Boiler Citation Details In-Document Search Title: Economic Analysis for Conceptual Design of Supercritical ...

  13. Pt and Pd catalyzed oxidation of Li2O2 and DMSO during Li–O2 battery charging

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

    Gittleson, Forrest S.; Ryu, Won-Hee; Schwab, Mark; Tong, Xiao; Taylor, André D.

    2016-01-01

    Rechargeable Li-O2 and Li-air batteries require electrode and electrolyte materials that synergistcally promote long-term cell operation. We investigate the role of noble metals Pt and Pd as catalysts for the Li-O2 oxidation process and their compatibility with a dimethyl sulfoxide (DMSO) based electrolyte. Lastly, we identify a basis for low potential Li2O2 evolution followed by oxidative decomposition of the electrolyte to form carbonate side products.

  14. 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.

  15. Strain-induced phase and oxygen-vacancy stability in ionic interfaces from first-principles calculations

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

    Aidhy, Dilpuneet S.; Liu, Bin; Zhang, Yanwen; Weber, William J.

    2014-12-03

    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.

  16. 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.

  17. First-principles study of direct and narrow band gap semiconducting β -CuGaO2

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

    Nguyen, Manh Cuong; Zhao, Xin; Wang, Cai-Zhuang; Ho, Kai-Ming

    2015-04-16

    Semiconducting oxides have attracted much attention due to their great stability in air or water and the abundance of oxygen. Recent success in synthesizing a metastable phase of CuGaO2 with direct narrow band gap opens up new applications of semiconducting oxides as absorber layer for photovoltaics. Using first-principles density functional theory calculations, we investigate the thermodynamic and mechanical stabilities as well as the structural and electronic properties of the β-CuGaO2 phase. Our calculations show that the β-CuGaO2 structure is dynamically and mechanically stable. The energy band gap is confirmed to be direct at the Γ point of Brillouin zone. Inmore » conclusion, the optical absorption occurs right at the band gap edge and the density of states near the valance band maximum is large, inducing an intense absorption of light as observed in experiment.« less

  18. 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

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

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

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

    2014-11-20

    Here, 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. Moreover, 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.

  20. 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.

  1. 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.

  2. 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.

  3. Photoinduced electron transfer in perylene-TiO2 nanoassemblies

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

    ABSTRACT: The photosensitization effect of three perylene dye derivatives on titanium dioxide nanoparticles (TiO2 NPs) has been investigated. The dyes used, 1,7-dibromoperylene-3,4...

  4. Ultrafast Multiphoton Pump-probe Photoemission Excitation Pathways in Rutile TiO2(110)

    SciTech Connect (OSTI)

    Argondizzo, Adam; Cui, Xuefeng; Wang, Cong; Sun, Huijuan; Shang, Honghui; Zhao, Jin; Petek, Hrvoje

    2015-04-27

    We investigate the spectroscopy and photoinduced electron dynamics within the conduction band of reduced rutile TiO2(110) surface by multiphoton photoemission (mPP) spectroscopy with wavelength tunable ultrafast (!20 fs) laser pulse excitation. Tuning the mPP photon excitation energy between 2.9 and 4.6 eV reveals a nearly degenerate pair of new unoccupied states located at 2.73 ± 0.05 and 2.85 ± 0.05 eV above the Fermi level, which can be analyzed through the polarization and sample azimuthal orientation dependence of the mPP spectra. Based on the calculated electronic structure and optical transition moments, as well as related spectroscopic evidence, we assign these resonances to transitions between Ti 3d bands of nominally t2g and eg symmetry, which are split by crystal field. The initial states for the optical transition are the reduced Ti3+ states of t2g symmetry populated by formation oxygen vacancy defects, which exist within the band gap of TiO2. Furthermore,we studied the electron dynamics within the conduction band of TiO2 by three-dimensional time-resolved pump-probe interferometric mPP measurements. The spectroscopic and time-resolved studies reveal competition between 2PP and 3PP processes where the t2g-eg transitions in the 2PP process saturate, and are overtaken by the 3PP process initiated by the band-gap excitation from the valence band of TiO2.

  5. 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.

  6. Identification of an Archean marine oxygen oasis

    SciTech Connect (OSTI)

    Riding, Dr Robert E; Fralick, Dr Philip; Liang, Liyuan

    2014-01-01

    The early Earth was essentially anoxic. A number of indicators suggest the presence of oxygenic photosynthesis 2700 3000 million years (Ma) ago, but direct evidence for molecular oxygen (O2) in seawater has remained elusive. Here we report rare earth element (REE) analyses of 2800 million year old shallowmarine limestones and deep-water iron-rich sediments at Steep Rock Lake, Canada. These show that the seawater from which extensive shallow-water limestones precipitated was oxygenated, whereas the adjacent deeper waters where iron-rich sediments formed were not. We propose that oxygen promoted limestone precipitation by oxidative removal of dissolved ferrous iron species, Fe(II), to insoluble Fe(III) oxyhydroxide, and estimate that at least 10.25 M oxygen concentration in seawater was required to accomplish this at Steep Rock. This agrees with the hypothesis that an ample supply of dissolved Fe(II) in Archean oceans would have hindered limestone formation. There is no direct evidence for the oxygen source at Steep Rock, but organic carbon isotope values and diverse stromatolites in the limestones suggest the presence of cyanobacteria. Our findings support the view that during the Archean significant oxygen levels first developed in protected nutrient-rich shallow marine habitats. They indicate that these environments were spatially restricted, transient, and promoted limestone precipitation. If Archean marine limestones in general reflect localized oxygenic removal of dissolved iron at the margins of otherwise anoxic iron-rich seas, then early oxygen oases are less elusive than has been assumed.

  7. Electrode Interface Dictates Oxygen Evolution from Lithium Peroxide in

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

    Li-O2 Batteries - Joint Center for Energy Storage Research December 16, 2014, Research Highlights Electrode Interface Dictates Oxygen Evolution from Lithium Peroxide in Li-O2 Batteries Isolation of the charge reaction from the discharge in Li-O2 cells by utilizing electrodes prefilled with commercial lithium peroxide provides a unique method to understand interfacial properties. OER is very facile on TiC, which lacks a significant oxide film and occurs at a much lower overpotential relative

  8. DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

    DOE Patents [OSTI]

    Bradner, H.; Gordon, H.S.

    1957-12-24

    A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

  9. Hydrogen (H2) Production by Oxygenic Phototrophs

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

    Production by Oxygenic Phototrophs Eric L. Hegg Michigan State University Great Lakes Bioenergy Research Center Bioresour. Technol. 2011, 102, 8589-8604 Major Challenges to H 2 Photoproduction Biological Challenges * Poor efficiency of H 2 production * Poor heterologous expression of H 2 -forming enzymes * Low quantum yields * Competition for reducing equivalents; poor electron coupling * Sensitivity of H 2 -forming enzymes to O 2 M. Ghirardi, Abstract #1751, Honolulu PRiME 2012 Technical

  10. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. The in situ electrical conductivity and Seebeck coefficient measurements were made on LSFT at 1000 and 1200 C over the oxygen activity range from air to 10{sup -15} atm. The electrical conductivity measurements exhibited a p to n type transition at an oxygen activity of 1 x 10{sup -10} at 1000 C and 1 x 10{sup -6} at 1200 C. Thermogravimetric studies were also carried out over the same oxygen activities and temperatures. Based on the results of these measurements, the chemical and mechanical stability range of LSFT were determined and defect structure was established. The studies on the fracture toughness of the LSFT and dual phase membranes exposed to air and N{sub 2} at 1000 C was done and the XRD and SEM analysis of the specimens were carried out to understand the structural and microstructural changes. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affect the mechanical properties. A complete transformation of fracture behavior was observed in the N{sub 2} treated LSFT samples. Further results to investigate the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Recent results on transient kinetic data are presented. The 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model is used to study ''frozen'' profiles in patterned or composite membranes.

  11. 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

  12. Temperature-dependent local structural properties of redox Pt nanoparticles on TiO2 and ZrO2 supports

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

    Jeong, Eun -Suk; Park, Chang -In; Jin, Zhenlan; Hwang, In -Hui; Son, Jae -Kwan; Kim, Mi -Young; Choi, Jae -Soon; Han, Sang -Wook

    2015-01-21

    This paper examined the local structural properties of Pt nanoparticles on SiO2, TiO2–SiO2, and ZrO2–SiO2 supports to better understand the impact of oxide-support type on the performance of Pt-based catalysts. In situ X-ray absorption fine structure (XAFS) measurements were taken for the Pt L3-edge in a temperature range from 300 to 700 K in He, H2, and O2 gas environments. The XAFS measurements demonstrated that Pt atoms were highly dispersed on TiO2–SiO2 and ZrO2–SiO2 forming pancake-shaped nanoparticles, whereas Pt atoms formed larger particles of hemispherical shapes on SiO2 supports. Contrary to the SiO2 case, the coordination numbers for Pt, Ti,more » and Zr around Pt atoms on the TiO2–SiO2 and ZrO2–SiO2 supports were nearly constant from 300 to 700 K under the different gas environments. These results are consistent with the improvements in thermal stability of Pt nanoparticles achieved by incorporating TiO2 or ZrO2 on the surface of SiO2 supports. XAFS analysis further indicated that the enhanced dispersion and stability of Pt were a consequence of the strong metal support interaction via Pt–Ti and Pt–Zr bonds.« less

  13. Predicting Chemical Pathways for Li-O2 Batteries - Joint Center...

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

    March 6, 2014, Research Highlights Predicting Chemical Pathways for Li-O2 Batteries ... figure) and (LiO2)6 (red curve, upper figure) to Li2O2 using quantum chemical theory. ...

  14. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; N. Nagabhushana; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. Thermogravimetric analysis (TGA) was carried out on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} to investigate oxygen deficiency ({delta}) of the sample. The TGA was performed in a controlled atmosphere using oxygen, argon, carbon monoxide and carbon dioxide with adjustable gas flow rates. In this experiment, the weight loss and gain of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} was directly measured by TGA. The weight change of the sample was evaluated at between 600 and 1250 C in air or 1000 C as a function of oxygen partial pressure. The oxygen deficiencies calculated from TGA data as a function of oxygen activity and temperature will be estimated and compared with that from neutron diffraction measurement in air. The LSFT and LSFT/CGO membranes were fabricated from the powder obtained from Praxair Specialty Ceramics. The sintered membranes were subjected to microstructure analysis and hardness analysis. The LSFT membrane is composed of fine grains with two kinds of grain morphology. The grain size distribution was characterized using image analysis. In LSFT/CGO membrane a lot of grain pullout was observed from the less dense, porous phase. The hardness of the LSFT and dual phase membranes were studied at various loads. The hardness values obtained from the cross section of the membranes were also compared to that of the values obtained from the surface. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. Measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} as a function of temperature an oxygen partial pressure are reported. Further analysis of the dilatometry data obtained previously is presented. A series of isotope transients

  15. 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

  16. High-Potential Electrocatalytic O2 Reduction with Nitroxyl / NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis

    SciTech Connect (OSTI)

    Gerken, James B.; Stahl, Shannon S.

    2015-07-15

    Efficient reduction of O2 to water is a central challenge in energy conversion and aerobic oxidation catalysis. In the present study, we investigate the electrochemical reduction of O2 with soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as TEMPO (2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl), nor NOx species, such as sodium nitrite, are effective mediators of electrochemical O2 reduction. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction at electrochemical potentials of 0.19–0.33 V (vs. Fc/Fc+) in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The high potentials observed with this ORR system benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  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. A theoretical study of the stability of anionic defects in cubic ZrO2 at extreme conditions

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

    Samanta, Amit

    2016-02-19

    Using first principles density functional theory calculations, we present a study of the structure, mobility, and the thermodynamic stability of anionic defects in the high-temperature cubic phase of ZrO2. Our results suggest that the local structure of an oxygen interstitial depends on the charge state and the cubic symmetry of the anionic sublattice is unstable at 0 K. In addition, the oxygen interstitials and the vacancies exhibit symmetry breaking transitions to low-energy structures with tetragonal distortion of the oxygen sublattice at 0 K. However, the vibrational entropy stabilizes the defect structures with cubic symmetry at 2600–2980 K. The formation freemore » energies of the anionic defects and Gibbs free energy changes associated with different defect reactions are calculated by including the vibrational free energy contributions and the effect of pressure on these defect structures. By analyzing the defect chemistry, we obtain the defect concentrations at finite temperature and pressure conditions using the zero temperature ab initio results as input and find that at low oxygen partial pressures, neutral oxygen vacancies are most dominant and at high oxygen partial pressures, doubly charged anionic defects are dominant. As a result, the relevance of the results to the thermal protective coating capabilities of zirconium-based ceramic composites is elucidated.« less

  19. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-05-01

    , measurements of the chemical and thermal expansion as a function of temperature and p{sub O2} are described.

  20. Enhanced O-2 Selectivity versus N-2 by Partial Metal Substitution in Cu-BTC

    SciTech Connect (OSTI)

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

    2015-03-24

    Here, we describe the homogeneous substitution of Mn, Fe, and Co at various levels into a prototypical metal organic framework (MOP), 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 O-2/N-2 selectivities determined experimentally at 77 K and the difference in O-2 and N-2 binding energies calculated from DFT modeling 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 (273-298 K) as compared to all other metals studied, indicative of favorable interactions between N-2 and coordinatively unsaturated Fe metal centers. Interestingly, 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.

  1. 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

  2. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect (OSTI)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  3. Oxygen Transport Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay

    2008-08-30

    The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

  4. IR Imaging Using Arrays of SiO2 Micromechanical Detectors

    SciTech Connect (OSTI)

    Grbovic, Dragoslav; Lavrik, Nickolay V; Rajic, Slobodan; Datskos, Panos G; Hunter, Scott Robert

    2012-01-01

    In this letter, we describe the fabrication of an array of bimaterial detectors for infrared (IR) imaging that utilize SiO2 as a structural material. All the substrate material underneath the active area of each detector element was removed. Each detector element incorporates an optical resonant cavity layer in the IR absorbing region of the sensing element. The simplified microfabrication process requires only four photolithographic steps with no wet etching or sacrificial layers. The thermomechanical deflection sensitivity was 7.9 10-3 rad/K which corresponds to a noise equivalent temperature difference (NETD) of 2.9 mK. In the present work the array was used to capture IR images while operating at room temperature and atmospheric pressure and no need for vacuum packaging. The average measured NETD of our IR detector system was approximately 200 mK but some sensing elements exhibited an NETD of 50 mK.

  5. Superconductivity in semimetallic Bi3O2S3

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

    Li, L.; Parker, D.; Babkevich, P.; Yang, L.; Ronnow, H. M.; Sefat, A. S.

    2015-03-12

    We report in this paper a further investigation on the thermodynamic and transport properties, and an assessment of theoretical calculations, for the BiS2-layered Bi3O2S3 superconductor. The polycrystalline sample is synthesized with a superconducting transition temperature of Tconset=5.75K and Tczero=4.03K (≈Tcmag) that drops to 3.3 K by applying a hydrostatic pressure of 6 kbar. Density-of-states (DOS) calculations give substantial hybridization between Bi, O, and S, with Bi the largest component of DOS, which supports the idea that the BiS2 layer is relevant for producing electron-phonon coupling. An analysis of previously published specific heat data for Bi3O2S3 is additionally suggestive of amore » strong electron-phonon interaction in the Bi-O-S system. The analysis of the Seebeck coefficient results strongly suggests that Bi3O2S3 is a semimetal. In fact, we found the semimetallic or narrow band gap behavior may occur in certain other materials in the BiS2-layered class of materials, such as Bi4O4S3.« less

  6. Absorption process for producing oxygen and nitrogen and solution therefor

    DOE Patents [OSTI]

    Roman, I.C.; Baker, R.W.

    1990-09-25

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible. 1 figure

  7. Absorption process for producing oxygen and nitrogen and solution therefor

    DOE Patents [OSTI]

    Roman, Ian C. [Wilmington, DE; Baker, Richard W. [Palo Alto, CA

    1990-09-25

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

  8. Absorption process for producing oxygen and nitrogen and solution therefor

    DOE Patents [OSTI]

    Roman, Ian C.

    1984-01-01

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

  9. Removal of Hazardous Pollutants from Wastewaters: Applications of TiO 2 -SiO 2 Mixed Oxide Materials

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

    Rasalingam, Shivatharsiny; Peng, Rui; Koodali, Ranjit T.

    2014-01-01

    The direct release of untreated wastewaters from various industries and households results in the release of toxic pollutants to the aquatic environment. Advanced oxidation processes (AOP) have gained wide attention owing to the prospect of complete mineralization of nonbiodegradable organic substances to environmentally innocuous products by chemical oxidation. In particular, heterogeneous photocatalysis has been demonstrated to have tremendous promise in water purification and treatment of several pollutant materials that include naturally occurring toxins, pesticides, and other deleterious contaminants. In this work, we have reviewed the different removal techniques that have been employed for water purification. In particular, the applicationmore » of TiO 2 -SiO 2 binary mixed oxide materials for wastewater treatment is explained herein, and it is evident from the literature survey that these mixed oxide materials have enhanced abilities to remove a wide variety of pollutants.« less

  10. A comment on the thermal conductivity of (U,Pu)O2 and (U,Th)O2 by molecular dynamics with adjustment for phonon-spin scattering

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

    Cooper, Michael William D.; Liu, Xiang -Yang; Stanek, Christopher Richard; Andersson, David Anders

    2016-07-15

    In this study, a new approach for adjusting molecular dynamics results on UO2 thermal conductivity to include phonon-spin scattering has been used to improve calculations on Ux Pu1–x O2 and UxTh1xO2. We demonstrate that by including spin scattering a strong asymmetry as a function of uranium actinide fraction, x, is obtained. Greater degradation is shown for UxTh1–xO2 than UxPu1-xO2. Minimum thermal conductivities are predicted at U0.97Pu0.03O2 and U0.58Th0.42O2, although the degradation in UxPu1–xO2 is negligible relative to pure UO2.

  11. 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.

  12. 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.

  13. STUDY OF USING OXYGEN-ENRICHED COMBUSTION AIR FOR LOCOMOTIVE...

    Office of Scientific and Technical Information (OSTI)

    ... Evaluation o f Polymeric Membranes for Oxygen-Enrichment of Air, DOEAD- 127 10- 1, U S . ... fLom Gas Turbine Engines, Atmospheric Pollution by Aircraft Engines, AGARD CP-125, Paper ...

  14. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-11-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the current research, the electrical conductivity and Seebeck coefficient were measured as a function of temperature in air. Based on these measurements, the charge carrier concentration, net acceptor dopant concentration, activation energy of conduction and mobility were estimated. The studies on the fracture toughness of the LSFT and dual phase membranes at room temperature have been completed and reported previously. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affects the mechanical properties. To study the effect of temperature on the membranes when exposed to an inert environment, the membranes (LAFT and Dual phase) were heat treated at 1000 C in air and N{sub 2} atmosphere and hardness and fracture toughness of the membranes were studied after the treatment. The indentation method was used to find the fracture toughness and the effect of the heat treatment on the mechanical properties of the membranes. Further results on the investigation of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appears to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model will serve to study ''frozen'' profiles in patterned or composite membranes.

  15. 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

  16. 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

  17. Low NOx combustion using cogenerated oxygen and nitrogen streams

    DOE Patents [OSTI]

    Kobayashi, Hisashi; Bool, Lawrence E.; Snyder, William J.

    2009-02-03

    Combustion of hydrocarbon fuel is achieved with less formation of NOx by feeding the fuel into a slightly oxygen-enriched atmosphere, and separating air into oxygen-rich and nitrogen-rich streams which are fed separately into the combustion device.

  18. 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 ...

  19. 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...

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

    Office of Scientific and Technical Information (OSTI)

    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, ...

  1. Visible Light Absorption of N-Doped TiO2 Rutile Using (LR/RT...

    Office of Scientific and Technical Information (OSTI)

    N-Doped TiO2 Rutile Using (LRRT)-TDDFT and Active Space EOMCCSD Calculations Citation Details In-Document Search Title: Visible Light Absorption of N-Doped TiO2 Rutile Using ...

  2. 238PuO2 Fuel and Dosimetry (Technical Report) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Technical Report: 238PuO2 Fuel and Dosimetry Citation Details In-Document Search Title: 238PuO2 Fuel and Dosimetry 238Pu is an ideal material for use as a heat source with its ...

  3. 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...

  4. Chemistry - Oxygen Vacancies and Catalysis on Ceria Surfaces

    SciTech Connect (OSTI)

    Campbell, Charles T.; Peden, Charles HF.

    2005-07-29

    Chemistry occurring at the surface of metal oxides is critical in a variety of industrial applications including catalysis and photocatalysis, optical display technology, solar energy devices and corrosion prevention. Defects have long been recognized to be the most reactive sites on the surfaces of many oxide materials. The most common types of defects present on the surfaces of metal oxides are oxygen vacancies and step edges. The nature of surface oxygen vacancies, and their number, distribution and diffusion across the surface of oxides, are thus issues of major scientific importance. One of the most interesting oxides in this respect is CeO2, since oxygen vacancies play the key role in giving this material it's industrially important ''oxygen-storage capacity''. This capacity makes modern automotive exhaust treatment catalysts containing CeO2 much more effective than their predecessors without CeO2. Ceria is also well known as a support which enhances the performance of transition metal catalysts, relative to other oxide supports, in a variety of other reactions including water-gas shift, steam reforming of oxygenates and PROX 1-7, all of which hold promise for enabling a hydrogen economy 1. Related to ceria's facile redox capacity (ability to rapidly form and eliminate oxygen vacancy defects) is the poorly understood observation that some less reducible oxides, such as zirconia (ZrO2), are used as additives that actually enhance this ''oxygen storage'' property of CeO2. In this issue, Esch and coworkers in Trieste, Italy report an exciting study that for the first time clearly elucidates the structure, distribution and formation of oxygen vacancies on a cerium oxide surface 8. They have elegantly combined beautiful, atomic-resolution imaging using scanning-tunneling microscopy (STM) on a ceria surface with state-of-the-art quantum mechanical calculations using Density Functional Theory (DFT) to raise our understanding of CeO2 surfaces to a much higher level

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. Solid state oxygen sensor

    DOE Patents [OSTI]

    Garzon, F.H.; Chung, B.W.; Raistrick, I.D.; Brosha, E.L.

    1996-08-06

    Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer. 4 figs.

  10. Solid state oxygen sensor

    DOE Patents [OSTI]

    Garzon, Fernando H.; Chung, Brandon W.; Raistrick, Ian D.; Brosha, Eric L.

    1996-01-01

    Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer.

  11. Role of HfO2/SiO2 thin-film interfaces in near-ultraviolet absorption and pulsed laser damage

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

    Papernov, Semyon; Kozlov, Alexei A.; Oliver, James B.; Smith, Chris; Jensen, Lars; Guenster, Stefan; Maedebach, Heinrich; Ristau, Detlev

    2016-07-15

    Here, the role of thin-film interfaces in the near-ultraviolet (near-UV) absorption and pulsed laser-induced damage was studied for ion-beam-sputtered and electron-beam-evaporated coatings comprised from HfO2 and SiO2 thin-film pairs. To separate contributions from the bulk of the film and from interfacial areas, absorption and damage threshold measurements were performed for a one-wave (355-nm wavelength) thick, HfO2 single-layer film and for a film containing seven narrow HfO2 layers separated by SiO2 layers. The seven-layer film was designed to have a total optical thickness of HfO2 layers, equal to one wave at 355 nm and an E-field peak and average intensity similarmore » to a single-layer HfO2 film. Absorption in both types of films was measured using laser calorimetry and photothermal heterodyne imaging. The results showed a small contribution to total absorption from thin-film interfaces as compared to HfO2 film material. The relevance of obtained absorption data to coating near-UV, nanosecond-pulse laser damage was verified by measuring the damage threshold and characterizing damage morphology. The results of this study revealed a higher damage resistance in the seven-layer coating as compared to the single-layer HfO2 film in both sputtered and evaporated coatings. The results are explained through the similarity of interfacial film structure with structure formed during the codeposition of HfO2 and SiO2 materials.« less

  12. Chemical expansion affected oxygen vacancy stability in different oxide structures from first principles calculations

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

    Aidhy, Dilpuneet S.; Liu, Bin; Zhang, Yanwen; Weber, William J.

    2015-01-21

    We study the chemical expansion for neutral and charged oxygen vacancies in fluorite, rocksalt, perovskite and pyrochlores materials using first principles calculations. We show that the neutral oxygen vacancy leads to lattice expansion whereas the charged vacancy leads to lattice contraction. In addition, we show that there is a window of strain within which an oxygen vacancy is stable; beyond that range, the vacancy can become unstable. Using CeO2|ZrO2 interface structure as an example, we show that the concentration of oxygen vacancies can be manipulated via strain, and the vacancies can be preferentially stabilized. Furthermore, these results could serve asmore » guiding principles in predicting oxygen vacancy stability in strained systems and in the design of vacancy stabilized materials.« less

  13. Chemical expansion affected oxygen vacancy stability in different oxide structures from first principles calculations

    SciTech Connect (OSTI)

    Aidhy, Dilpuneet S.; Liu, Bin; Zhang, Yanwen; Weber, William J.

    2015-03-01

    We study the chemical expansion for neutral and charged oxygen vacancies in fluorite, rocksalt, perovskite and pyrochlores materials using first principles calculations. We show that the neutral oxygen vacancy leads to lattice expansion whereas the charged vacancy leads to lattice contraction. In addition, we show that there is a window of strain within which an oxygen vacancy is stable; beyond that range, the vacancy can become unstable. Using CeO2|ZrO2 interface structure as an example, we show that the concentration of oxygen vacancies can be manipulated via strain, and the vacancies can be preferentially stabilized. These results could serve as guiding principles in predicting oxygen vacancy stability in strained systems and in the design of vacancy stabilized materials.

  14. Modelling the thermal conductivity of (UxTh1-x)O2 and (UxPu1-x)O2

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

    Cooper, M. W. D.; Middleburgh, S. C.; Grimes, R. W.

    2015-07-15

    The degradation of thermal conductivity due to the non-uniform cation lattice of (UxTh1-x)O2 and (UxPu1-x)O2 solid solutions has been investigated by molecular dynamics, using the non-equilibrium method, from 300 to 2000 K. Degradation of thermal conductivity is predicted in (UxTh1-x)O2 and (UxPu1-x)O2 as compositions deviate from the pure end members: UO2, PuO2 and ThO2. The reduction in thermal conductivity is most apparent at low temperatures where phonon-defect scattering dominates over phonon-phonon interactions. The effect is greater for (UxTh1-x)O2 than UxPu1-x)O2 due to the greater mismatch in cation size. Parameters for an analytical expressions have been developed that describe the predictedmore » thermal conductivities over the full temperature and compositional ranges. Finally, these expressions may be used in higher level fuel performance codes.« less

  15. 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.

  16. Solid state oxygen sensor

    DOE Patents [OSTI]

    Garzon, Fernando H.; Brosha, Eric L.

    1997-01-01

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures.

  17. Direct Numerical Simulations of Flame Propagation in Hydrogen-Oxygen

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

    Mixtures in Closed Vessels | Argonne Leadership Computing Facility Weak ignition behind a reflected shock in 2H2+O2 mixture Weak ignition behind a reflected shock in 2H2+O2 mixture at initially atmospheric pressure. The figure shows a two-dimensional distribution of density in the middle of a shock tube with a square cross-section of 5 cm x 5 cm. The end wall of the tube is on the right. The reflected bifurcated shock is on the left and is moving to the left. Weak ignition took place near

  18. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-10-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, Moessbauer spectroscopy was used to study the local environmentals of LSFT with various level of oxygen deficiency. Ionic valence state, magnetic interaction and influence of Ti on superexchange are discussed Stable crack growth studies on Dense OTM bars provided by Praxair were done at elevated temperature, pressure and elevated conditions. Post-fracture X-ray data of the OTM fractured at 1000 C in environment were refined by FullProf code and results indicate a distortion of the parent cubic perovskite to orthorhombic structure with reduced symmetry. TGA-DTA studies on the post-fracture samples also indicated residual effect arising from the thermal and stress history of the samples. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. The initial measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} are reported. Neutron diffraction measurements of the same composition are in agreement with both the stoichiometry and the kinetic behavior observed in coulometric titration measurements. A series of isotope transients under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The COCO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  19. 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

  20. 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.

  1. Oxygen partial pressure sensor

    DOE Patents [OSTI]

    Dees, Dennis W.

    1994-01-01

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  2. Oxygen partial pressure sensor

    DOE Patents [OSTI]

    Dees, D.W.

    1994-09-06

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

  3. Electrocatalyst for Oxygen Reduction with Reduced Platinum Oxidation and

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

    Dissolution Rates - Energy Innovation Portal Oxygen Reduction with Reduced Platinum Oxidation and Dissolution Rates Brookhaven National Laboratory Contact BNL About This Technology Publications: PDF Document Publication Electrodeposition of Pt onto RuO2 (110) Single-Crystal Surface (437 KB) <p> Results of a density functional theory calculation of atomic positions of platinum on an oxide surface, showing good agreement with experimental results.</p> Results of a density

  4. Surface control of epitaxial manganite films via oxygen pressure

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

    Tselev, Alexander; Vasudevan, Rama K.; Gianfrancesco, Anthony G.; Qiao, Liang; Ganesh, Panchapakesan; Meyer, Tricia L.; Lee, Ho Nyung; Biegalski, Michael D.; Baddorf, Arthur P.; Kalinin, Sergei

    2015-03-11

    The trend to reduce device dimensions demands increasing attention to atomic-scale details of structure of thin films as well as to pathways to control it. We found that this is of special importance in the systems with multiple competing interactions. We have used in situ scanning tunneling microscopy to image surfaces of La5/8Ca3/8MnO3 films grown by pulsed laser deposition. The atomically resolved imaging was combined with in situ angle-resolved X-ray photoelectron spectroscopy. We find a strong effect of the background oxygen pressure during deposition on structural and chemical features of the film surface. Deposition at 50 mTorr of O2 leadsmore » to mixed-terminated film surfaces, with B-site (MnO2) termination being structurally imperfect at the atomic scale. Moreover, a relatively small reduction of the oxygen pressure to 20 mTorr results in a dramatic change of the surface structure leading to a nearly perfectly ordered B-site terminated surface with only a small fraction of A-site (La,Ca)O termination. This is accompanied, however, by surface roughening at a mesoscopic length scale. The results suggest that oxygen has a strong link to the adatom mobility during growth. The effect of the oxygen pressure on dopant surface segregation is also pronounced: Ca surface segregation is decreased with oxygen pressure reduction.« less

  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. COLLOQUIUM: Extending the Ice Core Record of Atmospheric Composition and

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

    the Global Carbon and Oxygen Cycles Beyond 1 Million Years | Princeton Plasma Physics Lab 1, 2016, 2:15pm to 3:30pm Colloquia MBG Auditorium, PPPL (284 cap.) COLLOQUIUM: Extending the Ice Core Record of Atmospheric Composition and the Global Carbon and Oxygen Cycles Beyond 1 Million Years Professor John Higgins Princeton University Ice cores serve as a critical archive of past environmental conditions, providing constraints on global atmospheric composition and the climate of polar regions.

  7. Lithium salts for advanced lithium batteries: Li-metal, Li-O2, and Li-S

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

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

    2015-06-01

    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 andmore » conditions within such cells. Furthermore, this review explores the critical role Li-salts play in ensuring in these batteries viability.« less

  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. Integrated turbomachine oxygen plant

    SciTech Connect (OSTI)

    Anand, Ashok Kumar; DePuy, Richard Anthony; Muthaiah, Veerappan

    2014-06-17

    An integrated turbomachine oxygen plant includes a turbomachine and an air separation unit. One or more compressor pathways flow compressed air from a compressor through one or more of a combustor and a turbine expander to cool the combustor and/or the turbine expander. An air separation unit is operably connected to the one or more compressor pathways and is configured to separate the compressed air into oxygen and oxygen-depleted air. A method of air separation in an integrated turbomachine oxygen plant includes compressing a flow of air in a compressor of a turbomachine. The compressed flow of air is flowed through one or more of a combustor and a turbine expander of the turbomachine to cool the combustor and/or the turbine expander. The compressed flow of air is directed to an air separation unit and is separated into oxygen and oxygen-depleted air.

  10. Oxygen ion conducting materials

    DOE Patents [OSTI]

    Carter, J. David; Wang, Xiaoping; Vaughey, John; Krumpelt, Michael

    2004-11-23

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  11. Oxygen ion conducting materials

    DOE Patents [OSTI]

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2005-07-12

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  12. Oxygen ion conducting materials

    DOE Patents [OSTI]

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2003-01-01

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  13. Understanding Side Reactions in K-O2 Batteries for Improved Cycle Life: a

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

    Combined DFT and Experimental Study - Joint Center for Energy Storage Research November 12, 2014, Research Highlights Understanding Side Reactions in K-O2 Batteries for Improved Cycle Life: a Combined DFT and Experimental Study Combined experimental and DFT study have identified the main side reactions in a K-O2 battery, which are likely driven by the interaction of potassium with ether molecules and the crossover of O2 from the cathode. Scientific Achievement First comprehensive study of

  14. 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 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 deer09_singh.pdf (756.14 KB) More

  15. Instrument for stable high temperature Seebeck coefficient and resistivity measurements under controlled oxygen partial pressure

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

    Ihlefeld, Jon F.; Brown-Shaklee, Harlan James; Sharma, Peter Anand

    2015-04-28

    The transport properties of ceramic materials strongly depend on oxygen activity, which is tuned by changing the partial oxygen pressure (pO2) prior to and during measurement. Within, we describe an instrument for highly stable measurements of Seebeck coefficient and electrical resistivity at temperatures up to 1300 K with controlled oxygen partial pressure. An all platinum construction is used to avoid potential materials instabilities that can cause measurement drift. Two independent heaters are employed to establish a small temperature gradient for Seebeck measurements, while keeping the average temperature constant and avoiding errors associated with pO2-induced drifts in thermocouple readings. Oxygen equilibriummore » is monitored using both an O2 sensor and the transient behavior of the resistance as a proxy. A pO2 range of 10-25–100 atm can be established with appropriate gas mixtures. Seebeck measurements were calibrated against a high purity platinum wire, Pt/Pt–Rh thermocouple wire, and a Bi2Te3 Seebeck coefficient Standard Reference Material. To demonstrate the utility of this instrument for oxide materials we present measurements as a function of pO2 on a 1 % Nb-doped SrTiO3 single crystal, and show systematic changes in properties consistent with oxygen vacancy defect chemistry. Thus, an approximately 11% increase in power factor over a pO2 range of 10-19–10-8 atm at 973 K for the donor-doped single crystals is observed.« less

  16. 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.

  17. Phase Diagram of CuCrO2 in a Magnetic Field

    SciTech Connect (OSTI)

    Fishman, Randy Scott

    2011-01-01

    The magnetic phase diagram of CuCrO2 is constructed as a function of magnetic field and anisotropy using a trial spin state built from harmonics of a fundamental ordering wavevector. Whereas the multiferroic phase of CuCrO2 is a modified spin spiral with a 3-sublattice (SL) period, the phase diagram also contains 1-SL, 2-SL, 4-SL, and 5-SL collinear states which may be accessi- ble in the nonstoichiometric compound CuCrO2+ . For small anisotropy, CuCrO2 is predicted to undergo a transition between two modified spiral states with an intervening 3-SL collinear phase.

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

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

    More Documents & Publications Development of Compact Gaseous Sensors with Internal Reference for Monitoring O2 and NOx in Combustion Environments Compact Potentiometric NOx Sensor ...

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

    Office of Scientific and Technical Information (OSTI)

    Mechanisms of Oriented Attachment of TiO2 Nanocrystals in Vacuum and Humid Environments: Reactive Molecular Dynamics Citation Details In-Document Search Title: Mechanisms of ...

  20. Improved Li storage performance in SnO2 nanocrystals by a synergetic doping

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

    Wan, Ning; Lu, Xia; Wang, Yuesheng; Zhang, Weifeng; Bai, Ying; Hu, Yong -Sheng; Dai, Sheng

    2016-01-06

    Tin dioxide (SnO2) is a widely investigated lithium (Li) storage material because of its easy preparation, two-step storage mechanism and high specific capacity for lithium-ion batteries (LIBs). In this contribution, a phase-pure cobalt-doped SnO2 (Co/SnO2) and a cobalt and nitrogen co-doped SnO2 (Co-N/SnO2) nanocrystals are prepared to explore their Li storage behaviors. It is found that the morphology, specific surface area, and electrochemical properties could be largely modulated in the doped and co-doped SnO2 nanocrystals. Gavalnostatic cycling results indicate that the Co-N/SnO2 electrode delivers a specific capacity as high as 716 mAh g–1 after 50 cycles, and the same outstandingmore » rate performance can be observed in subsequent cycles due to the ionic/electronic conductivity enhancement by co-doping effect. Further, microstructure observation indicates the existence of intermediate phase of Li3N with high ionic conductivity upon cycling, which probably accounts for the improvements of Co-N/SnO2 electrodes. Furthermore, we find that the method of synergetic doping into SnO2 with Co and N, with which the electrochemical performances is enhanced remarkably, undoubtedly, will have an important influence on the material itself and community of LIBs as well.« less

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

    Office of Scientific and Technical Information (OSTI)

    Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6 Citation ... Resource Relation: Journal Name: Proceedings of the National Academy of Sciences of the ...

  2. Solid state oxygen sensor

    DOE Patents [OSTI]

    Garzon, F.H.; Brosha, E.L.

    1997-12-09

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures. 6 figs.

  3. Epitaxial single-crystal thin films of MnxTi1-xO2-δ grown on...

    Office of Scientific and Technical Information (OSTI)

    Epitaxial single-crystal thin films of MnxTi1-xO2- grown on (rutile)TiO2 substrates with ... Title: Epitaxial single-crystal thin films of MnxTi1-xO2- grown on (rutile)TiO2 ...

  4. Enhancing perovskite electrocatalysis through strain tuning of oxygen deficiency

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

    Barron, Sara C.; Lee, Ho Nyung; Petrie, Jonathan R.; Jeen, Hyoungjeen; Meyer, Tricia L.

    2016-05-27

    Oxygen vacancies in transition-metal oxides facilitate catalysis critical for energy storage and generation. However, promoting vacancies at the lower temperatures required for operation in devices such as metal–air batteries and portable fuel cells has proven elusive. Here we used thin films of perovskite-based strontium cobaltite (SrCoOx) to show that epitaxial strain is a powerful tool for manipulating the oxygen content under conditions consistent with the oxygen evolution reaction, yielding increasingly oxygen-deficient states in an environment where the cobaltite would normally be fully oxidized. The additional oxygen vacancies created through tensile strain enhance the cobaltite’s catalytic activity toward this important reactionmore » by over an order of magnitude, equaling that of precious-metal catalysts, including IrO2. Lastly, our findings demonstrate that strain in these oxides can dictate the oxygen stoichiometry independent of ambient conditions, allowing unprecedented control over oxygen vacancies essential in catalysis near room temperature.« less

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

    Office of Scientific and Technical Information (OSTI)

    Ethanol Steam Reforming on CoCeO2: The Effect of ZnO Promoter Citation Details In-Document Search Title: Ethanol Steam Reforming on CoCeO2: The Effect of ZnO Promoter A series of ...

  6. 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).

  7. Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres: Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres

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

    Khromova, Irina; Kužel, Petr; Brener, Igal; Reno, John L.; Chung Seu, U-Chan; Elissalde, Catherine; Maglione, Mario; Mounaix, Patrick; Mitrofanov, Oleg

    2016-06-27

    Monocrystalline titanium dioxide (TiO2) micro-spheres support two orthogonal magnetic dipole modes at terahertz (THz) frequencies due to strong dielectric anisotropy. For the first time, we experimentally detected the splitting of the first Mie mode in spheres of radii inline imagem through near-field time-domain THz spectroscopy. By fitting the Fano lineshape model to the experimentally obtained spectra of the electric field detected by the sub-wavelength aperture probe, we found that the magnetic dipole resonances in TiO2 spheres have narrow linewidths of only tens of gigahertz. Lastly, anisotropic TiO2 micro-resonators can be used to enhance the interplay of magnetic and electric dipolemore » resonances in the emerging THz all-dielectric metamaterial technology.« less

  8. High Selectivity Oxygen Delignification

    SciTech Connect (OSTI)

    Lucian A. Lucia

    2005-11-15

    Project Objective: The objectives of this project are as follows: (1) Examine the physical and chemical characteristics of a partner mill pre- and post-oxygen delignified pulp and compare them to lab generated oxygen delignified pulps; (2) Apply the chemical selectivity enhancement system to the partner pre-oxygen delignified pulps under mill conditions (with and without any predetermined amounts of carryover) to determine how efficiently viscosity is preserved, how well selectivity is enhanced, if strength is improved, measure any yield differences and/or bleachability differences; and (3) Initiate a mill scale oxygen delignification run using the selectivity enhancement agent, collect the mill data, analyze it, and propose any future plans for implementation.

  9. Hydrogen production using hydrogenase-containing oxygenic photosynthetic organisms

    DOE Patents [OSTI]

    Melis, Anastasios; Zhang, Liping; Benemann, John R.; Forestier, Marc; Ghirardi, Maria; Seibert, Michael

    2006-01-24

    A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

  10. Hydrogen Production Using Hydrogenase-Containing Oxygenic Photosynthetic Organisms

    DOE Patents [OSTI]

    Melis, A.; Zhang, L.; Benemann, J. R.; Forestier, M.; Ghirardi, M.; Seibert, M.

    2006-01-24

    A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

  11. The role of double TiO2 layers at the interface of FeSe/SrTiO3 superconductors

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

    Zou, Ke; Bozovic, Ian; Mandal, Subhasish; Albright, Stephen; Peng, Rui; Kumah, Divine; Simon, Georg; Dagdeviren, Omur; He, Xi; Schwarz, Udo; et al

    2016-05-16

    Here, we determine the surface reconstruction of SrTiO3 used to achieve superconducting FeSe films in experiments, which is different from the 1×1 TiO2-terminated SrTiO3 assumed by most previous theoretical studies. In particular, we identify the existence of a double TiO2 layer at the FeSe/SrTiO3 interface that plays two important roles. First, it facilitates the epitaxial growth of FeSe. Second, ab initio calculations reveal a strong tendency for electrons to transfer from an oxygen deficient SrTiO3 surface to FeSe when the double TiO2 layer is present. The double layer helps to remove the hole pocket in the FeSe at the Γmore » point of the Brillouin zone and leads to a band structure characteristic of superconducting samples. The characterization of the interface structure presented here is a key step towards the resolution of many open questions about this superconductor.« less

  12. 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.he common undoped polymorphs of TiO 2 are discussed and compared.he 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

  13. 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.

  14. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-05-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, in situ neutron diffraction was used to characterize the chemical and structural properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} (here after as L2SF55T) specimen, which was subject to measurements of neutron diffraction from room temperature to 900 C in N{sub 2}. Space group of R3c was found to result in a better refinement and is used in this study. The difference for crystal structure, lattice parameters and local crystal chemistry for LSFT nearly unchanged when gas environment switched from air to N{sub 2}. Stable crack growth studies on Dense OTM bars provided by Praxair were done at room temperature in air. A bridge-compression fixture was fabricated to achieve stable pre-cracks from Vickers indents. Post fracture evaluation indicated stable crack growth from the indent and a regime of fast fracture. Post-fracture X-ray data of the OTM fractured at 1000 C in environment were refined by FullProf code and results indicate a distortion of the parent cubic perovskite to orthorhombic structure with reduced symmetry. TGA-DTA studies on the post-fracture samples also indicated residual effect arising from the thermal and stress history of the samples. The thermal and chemical expansion of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} were studied at 800 {le} T {le} 1000 C and at {approx} 1 x 10{sup -15} {le} pO{sub 2} {le} 0.21 atm. The thermal expansion coefficient of the sample was calculated from the dilatometric analysis in the temperature range between room temperature and 1200 C in air. A series of isotope transients under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of

  15. Effects of Reduction Temperature and Metal-support Interactions on the Catalytic Activity of Pt/γ-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2

    SciTech Connect (OSTI)

    Alexeev, Oleg S.; Chin, Soo Yin; Engelhard, Mark H.; Ortiz-Soto, Lorna; Amiridis, Michael D.

    2005-12-15

    TiO2- and ?-Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in-situ FTIR after activation at various conditions and their catalytic properties were examined for the oxidation of CO in the absence and presence of H2 (PROX). When ?-Al2O3 was used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density on Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in-situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also be attributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive towards H2 than CO. Consequently, Pt/TiO2 shows substantially lower selectivities towards CO oxidation under PROX conditions than Pt/?-Al2O3.

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

    Office of Scientific and Technical Information (OSTI)

    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 ...

  17. Determination of NAD+ and NADH level in a Single Cell Under H2O2...

    Office of Scientific and Technical Information (OSTI)

    Capillary Electrophoresis Citation Details In-Document Search Title: Determination of NAD+ and NADH level in a Single Cell Under H2O2 Stress by Capillary Electrophoresis A ...

  18. Effect of Sodium on the Catalytic Properties of VOx/CeO2 Catalysts...

    Office of Scientific and Technical Information (OSTI)

    addition greatly alters the nature of the active sites by V-O-Ce bond cleavage and V-O-Na bond formation, leading to significantly reduced activity of the VOxCeO2 catalysts. ...

  19. Preparation of atomically flat rutile TiO2(001) surfaces for...

    Office of Scientific and Technical Information (OSTI)

    surfaces for oxide film growth This content will become publicly available on January 1, 2017 Prev Next Title: Preparation of atomically flat rutile TiO2(001) surfaces ...

  20. 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 ...

  1. Aqueous phase hydrodeoxygenation of polyols over Pd/WO3-ZrO2...

    Office of Scientific and Technical Information (OSTI)

    Aqueous phase hydrodeoxygenation of polyols over PdWO3-ZrO2: Role of Pd-WO3 interaction and hydrodeoxygenation pathway Citation Details In-Document Search This content will become ...

  2. 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...

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

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

    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. ...

  4. 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.

  5. 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

  6. 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).

  7. Enhanced Cycling Stability of Rechargeable Li-O2 Batteries Using...

    Office of Scientific and Technical Information (OSTI)

    reversibility. As a results, the cyclability of Li-O2 can be largely improved. Authors: Liu, Bin ; Xu, Wu ; Yan, Pengfei ; Sun, Xiuliang ; Bowden, Mark E. ; Read, Jeffrey ; Qian, ...

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

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Ultrahigh-pressure polyamorphism in GeO 2 ... Type: Published Article Journal Name: Proceedings of the National Academy of Sciences of ...

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

    Office of Scientific and Technical Information (OSTI)

    Ultrahigh-pressure polyamorphism in GeO 2 glass with coordination number >6 This content ... Type: Published Article Journal Name: Proceedings of the National Academy of Sciences of ...

  10. Kinetics of oxygen surface exchange on epitaxial Ruddlesden–Popper phases and correlations to first-principles descriptors

    SciTech Connect (OSTI)

    Lee, Yueh -Lin; Wang, Xiao Renshaw; Lee, Ho Nyung; Morgan, Dane; Shao-Horn, Yang; Lee, Dongkyu

    2015-12-17

    Through alignment of theoretical modeling with experimental measurements of oxygen surface-exchange kinetics on (001)-oriented La2–xSrxMO4+δ (M = Co, Ni, Cu) thin films, we demonstrate here the capability of the theoretical bulk O 2p-band centers to correlate with oxygen surface-exchange kinetics of the Ruddlesden–Popper oxide (RP214) (001)-oriented thin films. In addition, we demonstrate that the bulk O 2p-band centers can also correlate with the experimental activation energies for bulk oxygen transport and oxygen surface exchange of both the RP214 and the perovskite polycrystalline materials reported in the literature, indicating the effectiveness of the bulk O 2p-band centers in describing the associated energetics and kinetics. Here, we propose that the opposite slopes of the bulk O 2p-band center correlations between the RP214 and the perovskite materials are due to the intrinsic mechanistic differences of their oxygen surface-exchange kinetics bulk anionic transport.

  11. Kinetics of oxygen surface exchange on epitaxial Ruddlesden–Popper phases and correlations to first-principles descriptors

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

    Lee, Yueh -Lin; Wang, Xiao Renshaw; Lee, Ho Nyung; Morgan, Dane; Shao-Horn, Yang; Lee, Dongkyu

    2015-12-17

    Through alignment of theoretical modeling with experimental measurements of oxygen surface-exchange kinetics on (001)-oriented La2–xSrxMO4+δ (M = Co, Ni, Cu) thin films, we demonstrate here the capability of the theoretical bulk O 2p-band centers to correlate with oxygen surface-exchange kinetics of the Ruddlesden–Popper oxide (RP214) (001)-oriented thin films. In addition, we demonstrate that the bulk O 2p-band centers can also correlate with the experimental activation energies for bulk oxygen transport and oxygen surface exchange of both the RP214 and the perovskite polycrystalline materials reported in the literature, indicating the effectiveness of the bulk O 2p-band centers in describing the associatedmore » energetics and kinetics. Here, we propose that the opposite slopes of the bulk O 2p-band center correlations between the RP214 and the perovskite materials are due to the intrinsic mechanistic differences of their oxygen surface-exchange kinetics bulk anionic transport.« less

  12. Vehicle Technologies Office Merit Review 2016: Efficient Rechargeable Li/O2

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

    Batteries Utilizing Stable Inorganic Molten Salt Electrolytes | Department of Energy Efficient Rechargeable Li/O2 Batteries Utilizing Stable Inorganic Molten Salt Electrolytes Vehicle Technologies Office Merit Review 2016: Efficient Rechargeable Li/O2 Batteries Utilizing Stable Inorganic Molten Salt Electrolytes Presentation given by Liox at the 2016 DOE Vehicle Technologies Office and Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting about Batteries

  13. 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.

  14. Optical oxygen concentration monitor

    DOE Patents [OSTI]

    Kebabian, P.

    1997-07-22

    A system for measuring and monitoring the concentration of oxygen uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to one of oxygen`s A-band absorption lines. In a preferred embodiment, the argon line is split into sets of components of shorter and longer wavelengths by a magnetic field of approximately 2,000 Gauss that is parallel to the light propagation from the lamp. The longer wavelength components are centered on an absorption line of oxygen and thus readily absorbed, and the shorter wavelength components are moved away from that line and minimally absorbed. A polarization modulator alternately selects the set of the longer wavelength, or upshifted, components or the set of the shorter wavelength, or downshifted, components and passes the selected set to an environment of interest. After transmission over a path through that environment, the transmitted optical flux of the argon line varies as a result of the differential absorption. The system then determines the concentration of oxygen in the environment based on the changes in the transmitted optical flux between the two sets of components. In alternative embodiments modulation is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to either the emitting plasma of the lamp or the environment of interest. 4 figs.

  15. Controlled atmosphere for fabrication of cermet electrodes

    DOE Patents [OSTI]

    Ray, S.P.; Woods, R.W.

    1998-08-11

    A process is disclosed for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750 C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5--3000 ppm in order to obtain a desired composition in the resulting composite. 2 figs.

  16. Controlled atmosphere for fabrication of cermet electrodes

    DOE Patents [OSTI]

    Ray, Siba P.; Woods, Robert W.

    1998-01-01

    A process for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750.degree. C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5-3000 ppm in order to obtain a desired composition in the resulting composite.

  17. Catalyst Activity and Post-operation Analyses of Pt/TiO2 (Rutile) Catalysts Used in the Sulfuric Acid Decomposition Reaction

    SciTech Connect (OSTI)

    Lucia M. Petkovic; Daniel M. Ginosar; Harry W. Rollins; Kyle C. Burch; Patrick J. Pinhero; Helen H. Farrell

    2007-06-01

    Production of hydrogen by splitting of water at lower temperatures than by direct thermal decomposition can be achieved by a series of particular chemical reactions that establish a thermochemical cycle [1]. Among the high number of thermochemical water-splitting cycles proposed in the literature [2], the sulfur-based group is of considerable interest. All the sulfur-based cycles employ the catalytic decomposition of sulfuric acid into SO2 and O2. The produced O2 corresponds to the O2 generated from water in the overall cycle. Research performed at the Idaho National Laboratory [3] has found that even one of the most stables catalysts, Pt supported on low surface area titania, deactivates with time on stream (TOS). To develop an understanding of the factors that cause catalyst deactivation, samples of 1% Pt supported on titania (rutile) catalyst were submitted to flowing concentrated sulfuric acid at 1123 K and atmospheric pressure for different TOSs between 0 and 548 h and a number of chemical and spectroscopic analyses applied to the spent samples.

  18. 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.

  19. Results from ORNL characterization of ZrO2-500-AK2 - surrogate TRISO material

    SciTech Connect (OSTI)

    Kercher, Andrew K; Hunn, John D

    2005-06-01

    This document is a compilation of the characterization data for the TRISO-coated surrogate particles designated ZrO2-500-AK2 that was produced at Oak Ridge National Laboratory (ORNL) as part of the Advanced Gas Reactor Fuel Development and Qualification (AGR) program. The ZrO2-500-AK2 material contains nominally 500 {micro}m kernels of yttria-stabilized zirconia (YSZ) coated with all TRISO layers (buffer, inner pyrocarbon, silicon carbide, and outer pyrocarbon). The ZrO2-500-AK2 material was created for: (1) irradiation testing in the High Flux Isotope Reactor (HFIR) and (2) limited dissemination to laboratories as deemed appropriate to the AGR program. This material was created midway into a TRISO fuel development program to accommodate a sudden opportunity to perform irradiation testing on surrogate material. While the layer deposition processes were chosen based on the best technical understanding at the time, technical progress at ORNL has led to an evolution in the perceived optimal deposition conditions since the creation of ZrO2-500-AK2. Thus, ZrO2-500-AK2 contains a reasonable TRISO microstructure, but does differ significantly from currently produced TRISO surrogates and fuel at ORNL. In this document, characterization data of the ZrO2-500-AK2 surrogate includes: size, shape, coating thickness, and density.

  20. 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

  1. Epitaxial single-crystal thin films of MnxTi1-xO2-δ grown on...

    Office of Scientific and Technical Information (OSTI)

    on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory Citation ... on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory ...

  2. Monolithic solid electrolyte oxygen pump

    DOE Patents [OSTI]

    Fee, Darrell C.; Poeppel, Roger B.; Easler, Timothy E.; Dees, Dennis W.

    1989-01-01

    A multi-layer oxygen pump having a one-piece, monolithic ceramic structure affords high oxygen production per unit weight and volume and is thus particularly adapted for use as a portable oxygen supply. The oxygen pump is comprised of a large number of small cells on the order of 1-2 millimeters in diameter which form the walls of the pump and which are comprised of thin, i.e., 25-50 micrometers, ceramic layers of cell components. The cell components include an air electrode, an oxygen electrode, an electrolyte and interconnection materials. The cell walls form the passages for input air and for exhausting the oxygen which is transferred from a relatively dilute gaseous mixture to a higher concentration by applying a DC voltage across the electrodes so as to ionize the oxygen at the air electrode, whereupon the ionized oxygen travels through the electrolyte and is converted to oxygen gas at the oxygen electrode.

  3. 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.

  4. Optical oxygen concentration monitor

    DOE Patents [OSTI]

    Kebabian, Paul

    1997-01-01

    A system for measuring and monitoring the concentration of oxygen uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to one of oxygen's A-band absorption lines. In a preferred embodiment, the argon line is split into sets of components of shorter and longer wavelengths by a magnetic field of approximately 2000 Gauss that is parallel to the light propagation from the lamp. The longer wavelength components are centered on an absorption line of oxygen and thus readily absorbed, and the shorter wavelength components are moved away from that line and minimally absorbed. A polarization modulator alternately selects the set of the longer wavelength, or upshifted, components or the set of the shorter wavelength, or downshifted, components and passes the selected set to an environment of interest. After transmission over a path through that environment, the transmitted optical flux of the argon line varies as a result of the differential absorption. The system then determines the concentration of oxygen in the environment based on the changes in the transmitted optical flux between the two sets of components. In alternative embodiments modulation is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to either the emitting plasma of the lamp or the environment of interest.

  5. 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.

  6. 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.

  7. ARM - Atmospheric Heat Budget

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

    The Atmospheric Heat Budget shows where the atmospheric heat energy comes from and where it goes. Practically all this energy ultimately comes from the sun in the form of the ...

  8. 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

  9. 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

  10. 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

  11. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-05-01

    Archimedes method. The bulk density was 5.029 and 5.57 g/cc for LSFT and dual phase membranes, respectively. The microstructure of the dual phase membrane was analyzed using SEM. It is evident from the micrograph that the microstructure is composed of dual phases. The dense circular regions are enclosed by the less dense, continuous phase which accommodates most of the pores. The pores are normally aggregated and found clustered along the dense regions where as the dense regions do not have pores. Upon closer observation of the micrograph it is revealed that the dense region has a clear circular cleavage or crack as their boundary. The circular cleavage clearly encompasses a dense region and which consists of no pore or any flaw that is visible. The size distribution of the dense, discontinuous regions is varying from 5 to 20 {micro}m with a D{sub 50} of 15 {micro}m. The grain size distribution was estimated from the micrographs using image analysis and a unimodal distribution of grains was observed with an average grain size of 1.99 {micro}m. The chemical compositions of the membranes were analyzed using EDS analysis and no other impurities were observed. The XRD analysis was carried out for the membranes and the phase purity was confirmed. The fracture toughness of LSFT membranes at room temperature has to be calculated using the Vickers indentation method. An electrochemical cell has been designed and built for measurements of the ionic conductivity by the use of blocking electrodes. Preliminary measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} are reported. Modifications to the apparatus to improve the data quality have been completed. Electron microscopy studies of the origin of the slow kinetics on reduction of ferrites have been initiated. A series of isotope transients under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also

  12. Atmospheric Radiation Measurement Program

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

    3 ARM 2003 Tom Ackerman Chief Scientist Tom Ackerman Chief Scientist ARM ARM Atmospheric Radiation Measurement Atmospheric Radiation Measurement WARNING! WARNING! Today is April 1 But that has NO bearing on this message Today is April 1 But that has NO bearing on this message ARM ARM Atmospheric Radiation Measurement Atmospheric Radiation Measurement Two Topics Two Topics * Status of ARM (quick overview) * Science plan - ARM in the next 5 years * Status of ARM (quick overview) * Science plan -

  13. Ammonia reactions with the stored oxygen in a commercial lean NOx trap catalyst

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

    Bartova, Sarka; Mracek, David; Koci, Petr; Marek, Milos; Choi, Jae -Soon

    2014-10-12

    Ammonia is an important intermediate of the NOx reduction in a NOx storage and reduction catalyst (aka lean NOx trap). NH3 formed under rich conditions in the reduced front part of the catalyst is transported by convection downstream to the unregenerated (still oxidized) zone of the catalyst, where it further reacts with the stored oxygen and NOx. In this paper, the kinetics and selectivity of NH3 reactions with the stored oxygen are studied in detail with a commercial Ba-based NOx storage catalyst containing platinum group metals (PGM), Ba and Ce oxides. Furthermore, steady-state NH3 decomposition, NH3 oxidation by O2 andmore » NO, and N2O decomposition are examined in light-off experiments. Periodic lean/rich cycling is measured first with O2 and NH3, and then with NOx + O2 and NH3 to discriminate between the NH3 reactions with the stored oxygen and the stored NOx. The reaction of NH3 with the stored O2 is highly selective towards N2, however a certain amount of NOx and N2O is also formed. The formed NOx by-product is efficiently adsorbed on the NOx storage sites such that the NOx is not detected at the reactor outlet except at high temperatures. The stored NOx reacts with NH3 feed in the next rich phase, contributing to the N2O formation. Water inhibits the reactions of NH3 with the stored oxygen. On the contrary, the presence of CO2 increases the NH3 consumption. Furthermore, CO2 is able to provide additional oxygen for NH3 oxidation, forming –CO in analogy to the reverse water gas shift reaction.« less

  14. Dilute Oxygen Combustion Phase I Final Report

    SciTech Connect (OSTI)

    Ryan, H.M.; Riley, M.F.; Kobayashi, H.

    1997-10-31

    A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NOx production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature (~1366 K) oxidant (7-27% O2 vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d+ scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d+ scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW (~0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NOx emissions

  15. Dilute Oxygen Combustion Phase 2 Final Report

    SciTech Connect (OSTI)

    Ryan, H.M.; Riley, M.F.; Kobayashi, H.

    2005-09-30

    A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NOx production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature (~1366 K) oxidant (7-27% O2 vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d+ scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d+ scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW (~0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NOx emissions

  16. Zero added oxygen for high quality sputtered ITO. A data science investigation of reduced Sn-content and added Zr

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

    Peshek, Timothy J.; Burst, James M.; Coutts, Timothy J.; Gessert, Timothy A.

    2016-01-19

    Here, we demonstrate mobilities of >45 cm2/V s for sputtered tin-doped indium oxide (ITO) films at zero added oxygen. All films were deposited with 5 wt. % SnO2, instead of the more conventional 8–10 wt. %, and had varying ZrO2 content from 0 to 3 wt. %, with a subsequent reduction in In2O3 content. Moreover, these films were deposited by radio-frequency magnetron sputtering from nominally stoichiometric targets with varying oxygen partial pressure in the sputter ambient. Anomalous behavior was discovered for films with no Zr-added, where a bimodality of high and low mobilities was discovered for nominally similar growth conditions.more » However, all films showed the lowest resistivity and highest mobilities when the oxygen partial pressure in the sputter ambient was zero. This result is contrasted with several other reports of ITO transport performance having a maximum for small but nonzero oxygen partial pressure. Our result is attributed to the reduced concentration of SnO2. The addition of ZrO2 yielded the highest mobilities at >55 cm2/V s and the films showed a modest increase in optical transmission with increasing Zr-content.« less

  17. Acetaldehyde Adsorption and Reaction onCeO2(100) Thin Films

    SciTech Connect (OSTI)

    Mullins, David R; Albrecht, Peter M

    2013-01-01

    This study reports and compares the adsorption and dissociation of acetaldehyde on oxidized and reduced CeOX(100) thin films. Acetaldehyde reacts and decomposes on fully oxidized CeO2(100) whereas it desorbs molecularly at low temperature on CeO2(111). The primary products are CO, CO2 and water along with trace amounts of crotonaldehyde and acetylene. The acetaldehyde adsorbs as the 2-acetaldehyde species, dioxyethylene. Decomposition proceeds by dehydrogenation through acetate and enolate intermediates. The reaction pathway is similar on the reduced CeO2-X(100) surface however the inability to react with surface O on the reduced surface results in H2 rather than H2O desorption and C is left on the surface rather than producing CO and CO2. C-O bond cleavage in the enolate intermediate followed by reaction with surface H results in ethylene desorption.

  18. Splitting of magnetic dipole modes in anisotropic TiO2 micro-spheres

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

    Khromova, Irina; Kuzel, Petr; Brener, Igal; Reno, John L.; Chung Seu, U-Chan; Elissalde, Catherine; Maglione, Mario; Mounaix, Patrick; Mitrofanov, Oleg

    2016-06-27

    Monocrystalline titanium dioxide (TiO2) micro-spheres support two orthogonal magnetic dipole modes at terahertz (THz) frequencies due to strong dielectric anisotropy. For the first time, we experimentally detected the splitting of the first Mie mode in spheres of radii inline imagem through near-field time-domain THz spectroscopy. By fitting the Fano lineshape model to the experimentally obtained spectra of the electric field detected by the sub-wavelength aperture probe, we found that the magnetic dipole resonances in TiO2 spheres have narrow linewidths of only tens of gigahertz. Lastly, anisotropic TiO2 micro-resonators can be used to enhance the interplay of magnetic and electric dipolemore » resonances in the emerging THz all-dielectric metamaterial technology.« less

  19. 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.

  20. High pressure oxygen furnace

    DOE Patents [OSTI]

    Morris, D.E.

    1992-07-14

    A high temperature high pressure oxygen furnace having a hybrid partially externally heated construction is disclosed. A metallic bar fabricated from an alloy having a composition of at least 45% nickel, 15% chrome, and 10% tungsten is utilized, the preferred alloy including 55% nickel, 22% chrome, 14% tungsten, 2% molybdenum, 3% iron (maximum) and 5% cobalt (maximum). The disclosed alloy is fabricated into 11/4 inch bar stock and has a length of about 17 inches. This bar stock is gun drilled for over 16 inches of its length with 0.400 inch aperture to define a closed high temperature, high pressure oxygen chamber. The opposite and closed end of the bar is provided with a small support aperture into which both a support and a thermocouple can be inserted. The closed end of the gun drilled bar is inserted into an oven, preferably heated by standard nickel chrome electrical elements and having a heavily insulated exterior. 5 figs.

  1. High pressure oxygen furnace

    DOE Patents [OSTI]

    Morris, Donald E.

    1992-01-01

    A high temperature high pressure oxygen furnace having a hybrid partially externally heated construction is disclosed. A metallic bar fabricated from an alloy having a composition of at least 45% nickel, 15% chrome, and 10% tungsten is utilized (the preferred alloy including 55% nickel, 22% chrome, 14% tungsten, 2% molybdenum, 3% iron (maximum) and 5% cobalt (maximum). The disclosed alloy is fabricated into 11/4 inch bar stock and has a length of about 17 inches. This bar stock is gun drilled for over 16 inches of its length with 0.400 inch aperture to define a closed high temperature, high pressure oxygen chamber. The opposite and closed end of the bar is provided with a small support aperture into which both a support and a thermocouple can be inserted. The closed end of the gun drilled bar is inserted into an oven, preferably heated by standard nickel chrome electrical elements and having a heavily insulated exterior.

  2. 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.

  3. Preparation of low oxygen-to-metal mixed oxide fuels for the advanced fast reactor

    SciTech Connect (OSTI)

    Kato, Masato; Nakamichi, Shinya; Takano, Tatsuo

    2007-07-01

    The preparation process for homogeneous mixed oxide pellets with a precise O/M ratio was established. The process was used to prepare pellets for heat treatments in two stages which consisted of the sintering process at high oxygen potential and the annealing process done in the atmosphere of controlled oxygen partial pressure. In the annealing process, it was found that abnormal growth of pores and occurrence of cracks were caused inside the pellet, and it was necessary for prevention of the microstructure change to control the oxygen potential of the atmosphere. Mixed oxide pellets with minor actinides were fabricated by the process and were provided to irradiation tests. (authors)

  4. Oxygen Transport Ceramic Membranes

    SciTech Connect (OSTI)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-08-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Modeling of the isotopic transients on operating membranes (LSCrF-2828 at 900 C) and a ''frozen'' isotope profile have been analyzed in conjunction with a 1-D model to reveal the gradient in oxygen diffusivity through the membrane under conditions of high chemical gradients.

  5. Fuel cell oxygen electrode

    DOE Patents [OSTI]

    Shanks, H.R.; Bevolo, A.J.; Danielson, G.C.; Weber, M.F.

    An oxygen electrode for a fuel cell utilizing an acid electrolyte has a substrate of an alkali metal tungsten bronze of the formula: A/sub x/WO/sub 3/ where A is an alkali metal and x is at least 0.2, which is covered with a thin layer of platinum tungsten bronze of the formula: Pt/sub y/WO/sub 3/ where y is at least 0.8.

  6. Fuel cell oxygen electrode

    DOE Patents [OSTI]

    Shanks, Howard R.; Bevolo, Albert J.; Danielson, Gordon C.; Weber, Michael F.

    1980-11-04

    An oxygen electrode for a fuel cell utilizing an acid electrolyte has a substrate of an alkali metal tungsten bronze of the formula: A.sub.x WO.sub.3 where A is an alkali metal and x is at least 0.2, which is covered with a thin layer of platinum tungsten bronze of the formula: Pt.sub.y WO.sub.3 where y is at least 0.8.

  7. 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.

  8. A Functional Impurity for Li-O2 Battery Cathode - Joint Center for Energy

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

    Storage Research December 2, 2015, Research Highlights A Functional Impurity for Li-O2 Battery Cathode Galvanostatic discharge curves of activated carbon cathodes (a) with different K-impurity levels (i.e. KAC4 to KAC16) at 0.1 mA/cm2 and the corresponding SEM images (b to e) of the discharged cathode. Scientific Achievement Demonstrated that alkali metal can be used as a catalyst Li-O2 cell cathode design and opens the possibility of future optimization of functional K-doping in carbon

  9. 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.

  10. 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 SiO2 Fracture: Chemomechanics with a Machine Learning Hybrid QM/MM Scheme SiO2 Fracture: Chemomechanics with a Machine Learning Hybrid QM/MM Scheme. Close-up of a crack tip in a multiscale quantum mechanical/molecular mechanical (QM/MM) simulation of "stress corrosion" cracking in amorphous silica glass. This project aims to elucidate the role of crack tip chemical reactions involving corrosive species such as water. Petascale computing

  11. Photochemistry in terrestrial exoplanet atmospheres. III. Photochemistry and thermochemistry in thick atmospheres on super Earths and mini Neptunes

    SciTech Connect (OSTI)

    Hu, Renyu; Seager, Sara

    2014-03-20

    Some super Earths and mini Neptunes will likely have thick atmospheres that are not H{sub 2}-dominated. We have developed a photochemistry-thermochemistry kinetic-transport model for exploring the compositions of thick atmospheres on super Earths and mini Neptunes, applicable for both H{sub 2}-dominated atmospheres and non-H{sub 2}-dominated atmospheres. Using this model to study thick atmospheres for wide ranges of temperatures and elemental abundances, we classify them into hydrogen-rich atmospheres, water-rich atmospheres, oxygen-rich atmospheres, and hydrocarbon-rich atmospheres. We find that carbon has to be in the form of CO{sub 2} rather than CH{sub 4} or CO in a H{sub 2}-depleted water-dominated thick atmosphere and that the preferred loss of light elements from an oxygen-poor carbon-rich atmosphere leads to the formation of unsaturated hydrocarbons (C{sub 2}H{sub 2} and C{sub 2}H{sub 4}). We apply our self-consistent atmosphere models to compute spectra and diagnostic features for known transiting low-mass exoplanets GJ 1214 b, HD 97658 b, and 55 Cnc e. For GJ 1214 b, we find that (1) C{sub 2}H{sub 2} features at 1.0 and 1.5 ?m in transmission and C{sub 2}H{sub 2} and C{sub 2}H{sub 4} features at 9-14 ?m in thermal emission are diagnostic for hydrocarbon-rich atmospheres; (2) a detection of water-vapor features and a confirmation of the nonexistence of methane features would provide sufficient evidence for a water-dominated atmosphere. In general, our simulations show that chemical stability has to be taken into account when interpreting the spectrum of a super Earth/mini Neptune. Water-dominated atmospheres only exist for carbon to oxygen ratios much lower than the solar ratio, suggesting that this kind of atmospheres could be rare.

  12. Atmospheric corrosion of lithium electrodes

    SciTech Connect (OSTI)

    Johnson, C.J.

    1981-10-01

    Atmospheric corrosion of lithium during lithium-cell assembly and the dry storage of cells prior to electrolyte fill has been found to initiate lithium corrosion pits and to form corrosion products. Scanning Electron Microscopy (SEM) was used to investigate lithium pitting and the white floccullent corrosion products. Electron Spectroscopy for Chemical Analysis (ESCA) and Auger spectroscopy in combination with X-ray diffraction were used to characterize lithium surfaces. Lithium surfaces with corrosion products were found to be high in carbonate content indicating the presence of lithium carbonate. Lithium electrodes dry stored in unfilled batteries were found to contain high concentration of lithium flouride a possible corrosion product from gaseous materials from the carbon monofluoride cathode. Future investigations of the corrosion phenomena will emphasize the effect of the corrosion products on the electrolyte and ultimate battery performance. The need to protect lithium electrodes from atmospheric exposure is commonly recognized to minimize corrosion induced by reaction with water, oxygen, carbon dioxide or nitrogen (1). Manufacturing facilities customarily limit the relative humidity to less than two percent. Electrodes that have been manufactured for use in lithium cells are typically stored in dry-argon containers. In spite of these precautions, lithium has been found to corrode over a long time period due to residual gases or slow diffusion of the same into storage containers. The purpose of this investigation was to determine the nature of the lithium corrosion.

  13. Effects of Reduction Temperature and Metal-Support Interactions on the Catalytic Activity of Pt/g-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2.

    SciTech Connect (OSTI)

    Alexeev,O.; Chin, S.; Engelhard, M.; Ortiz-Soto, L.; Amiridis, M.

    2005-01-01

    TiO2- and -Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in situ FTIR spectroscopy after activation at various conditions, and their catalytic properties were examined for the oxidation of CO in the absence and presence of H2 (PROX). When {gamma}-Al{sub 2}O{sub 3} was used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density on Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also be attributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive toward H{sub 2} than CO. Consequently, Pt/TiO{sub 2} shows substantially lower selectivities toward CO oxidation under PROX conditions than Pt/{gamma}-Al{sub 2}O{sub 3}.

  14. 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.

  15. 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.

    2016-01-01

    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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Community Atmosphere Model

    Energy Science and Technology Software Center (OSTI)

    2004-10-18

    The Community Atmosphere Model (CAM) is an atmospheric general circulation model that solves equations for atmospheric dynamics and physics. CAM is an outgrowth of the Community Climate Model at the National Center for Atmospheric Research (NCAR) and was developed as a joint collaborative effort between NCAR and several DOE laboratories, including LLNL. CAM contains several alternative approaches for advancing the atmospheric dynamics. One of these approaches uses a finite-volume method originally developed by personnel atmore » NASNGSFC, We have developed a scalable version of the finite-volume solver for massively parallel computing systems. FV-CAM is meant to be used in conjunction with the Community Atmosphere Model. It is not stand-alone.« less

  2. How reduced vacuum pumping capability in a coating chamber affects the laser damage resistance of HfO2/SiO2 antireflection and high reflection coatings.

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

    Field, Ella Suzanne; Bellum, John Curtis; Kletecka, Damon E.

    2016-06-01

    Optical coatings with the highest laser damage thresholds rely on clean conditions in the vacuum chamber during the coating deposition process. A low base pressure in the coating chamber, as well as the ability of the vacuum system to maintain the required pressure during deposition, are important aspects of limiting the amount of defects in an optical coating that could induce laser damage. Our large optics coating chamber at Sandia National Laboratories normally relies on three cryo pumps to maintain low pressures for e-beam coating processes. However, on occasion, one or more of the cryo pumps have been out ofmore » commission. In light of this circumstance, we explored how deposition under compromised vacuum conditions resulting from the use of only one or two cryo pumps affects the laser-induced damage thresholds of optical coatings. Finally, the coatings of this study consist of HfO2 and SiO2 layer materials and include antireflection coatings for 527 nm at normal incidence, and high reflection coatings for 527 nm, 45⁰ angle of incidence (AOI), in P-polarization (P-pol).« less

  3. Surface oxygen micropatterns on glow discharge polymer targets by photo irradiation

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

    Reynolds, Hannah; Baxamusa, Salmaan; Haan, Steven W.; Fitzsimmons, Paul; Carlson, Lane; Farrell, Mike; Nikroo, Abbas; Watson, Brian J.

    2016-02-24

    Recent simulations predict surface oxygen may be a significant source of disruptive perturbations in the implosion process of glow-discharge polymers (GDP) ablators at the National Ignition Facility. GDP material held in ambient atmospheric conditions showed an increase in mass when stored in light transparent containers, which suggests that photo exposure is a driving force for oxygen absorption. To investigate if surface oxygen is a contributing factor of disruptive perturbations during implosion, we developed a method to imprint a periodic micropattern of oxygen on the surface of GDP and used it to fabricate a flat sample for empirical testing.

  4. Singlet-Oxygen Generation From Individual Semiconducting and Metallic Nanostructures During Near-Infrared Laser Trapping

    SciTech Connect (OSTI)

    Smith, Bennett E.; Roder, Paden B.; Hanson, Jennifer L.; Manandhar, Sandeep; Devaraj, Arun; Perea, Daniel E.; Kim, Woo-Joong; Kilcoyne, Arthur L.; Pauzauskie, Peter J.

    2015-03-13

    Photodynamic therapy has been used for several decades in the treatment of solid tumors through the generation of reactive singlet-oxygen species (1O2). Recently, nanoscale metallic and semiconducting materials have been reported to act as photosensitizing agents with additional diagnostic and therapeutic functionality. To date there have been no reports of observing the generation of singlet-oxygen at the level of single nanostructures, particularly at near infrared (NIR) wavelengths. Here we demonstrate that NIR laser-tweezers can be used to observe the formation of singlet-oxygen produced from individual silicon and gold nanowires via use of a commercially available reporting dye. The laser trap also induces 2-photon photoexcitation of the dye following a chemical reaction with singlet oxygen. Corresponding 2-photon emission spectra confirms the generation of singlet oxygen from individual silicon nanowires at room temperature (30°C), suggesting a range of applications in understanding the impact of 1O2 on individual cancer cells.

  5. Atmosphere to Electrons

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

    ... Wind Forecast Improvement Project The Wind Forecast Improvement Project (WFIP) is a public private partnership consortium including DOE, the National Oceanic and Atmospheric ...

  6. Composite oxygen transport membrane

    DOE Patents [OSTI]

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2014-08-05

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  7. High Selectivity Oxygen Delignification

    SciTech Connect (OSTI)

    Arthur J. Ragauskas Lucian A. Lucia Hasan Jameel

    2005-09-30

    The overall objective of this program was to develop improved extended oxygen delignification (EOD) technologies for current U.S. pulp mill operations. This was accomplished by: (1) Identifying pulping conditions that optimize O and OO performance; (2) Identifying structural features of lignin that enhance reactivity towards EOD of high kappa pulps; (3) Identifying factors minimizing carbohydrate degradation and improve pulp strength of EOD high kappa pulps; (4) Developing a simple, reproducible method of quantifying yield gains from EOD; and (5) Developing process conditions that significantly reduce the capital requirements of EOD while optimizing the yield benefits. Key research outcomes included, demonstrating the use of a mini-O sequence such as (E+O)Dkf:0.05(E+O) or Dkf:0.05(E+O)(E+O) without interstage washing could capture approximately 60% of the delignification efficiency of a conventional O-stage without the major capital requirements associated with an O-stage for conventional SW kraft pulps. The rate of formation and loss of fiber charge during an O-stage stage can be employed to maximize net fiber charge. Optimal fiber charge development and delignification are two independent parameters and do not parallel each other. It is possible to utilize an O-stage to enhance overall cellulosic fiber charge of low and high kappa SW kraft pulps which is beneficial for physical strength properties. The application of NIR and multi-variant analysis was developed into a rapid and simple method of determining the yield of pulp from an oxygen delignification stage that has real-world mill applications. A focus point of this program was the demonstration that Kraft pulping conditions and oxygen delignification of high and low-kappa SW and HW pulps are intimately related. Improved physical pulp properties and yield can be delivered by controlling the H-factor and active alkali charge. Low AA softwood kraft pulp with a kappa number 30 has an average improvement of 2% in

  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. Economic Analysis for Conceptual Design of Supercritical O2-Based PC Boiler

    SciTech Connect (OSTI)

    Andrew Seltzer; Archie Robertson

    2006-09-01

    This report determines the capital and operating costs of two different oxygen-based, pulverized coal-fired (PC) power plants and compares their economics to that of a comparable, air-based PC plant. Rather than combust their coal with air, the oxygen-based plants use oxygen to facilitate capture/removal of the plant CO{sub 2} for transport by pipeline to a sequestering site. To provide a consistent comparison of technologies, all three plants analyzed herein operate with the same coal (Illinois No 6), the same site conditions, and the same supercritical pressure steam turbine (459 MWe). In the first oxygen-based plant, the pulverized coal-fired boiler operates with oxygen supplied by a conventional, cryogenic air separation unit, whereas, in the second oxygen-based plant, the oxygen is supplied by an oxygen ion transport membrane. In both oxygen-based plants a portion of the boiler exhaust gas, which is primarily CO{sub 2}, is recirculated back to the boiler to control the combustion temperature, and the balance of the flue gas undergoes drying and compression to pipeline pressure; for consistency, both plants operate with similar combustion temperatures and utilize the same CO{sub 2} processing technologies. The capital and operating costs of the pulverized coal-fired boilers required by the three different plants were estimated by Foster Wheeler and the balance of plant costs were budget priced using published data together with vendor supplied quotations. The cost of electricity produced by each of the plants was determined and oxygen-based plant CO{sub 2} mitigation costs were calculated and compared to each other as well as to values published for some alternative CO{sub 2} capture technologies.

  10. The role of film interfaces in near-ultraviolet absorption and pulsed-laser damage in ion-beam-sputtered coatings based on HfO2/SiO2 thin-film pairs

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

    Ristau, Detlev; Papernov, S.; Kozlov, A. A.; Oliver, J. B.; Smith, C.; Jensen, L.; Gunster, S.; Madebach, H.

    2015-11-23

    The role of thin-film interfaces in the near-ultraviolet absorption and pulsed-laser–induced damage was studied for ion-beam–sputtered and electron-beam–evaporated coatings comprised from HfO2 and SiO2 thin-film pairs. To separate contributions from the bulk of the film and from interfacial areas, absorption and damage-threshold measurements were performed for a one-wave (355-nm wavelength) thick, HfO2 single-layer film and for a film containing seven narrow HfO2 layers separated by SiO2 layers. The seven-layer film was designed to have a total optical thickness of HfO2 layers, equal to one wave at 355 nm and an E-field peak and average intensity similar to a single-layer HfO2more » film. Absorption in both types of films was measured using laser calorimetry and photothermal heterodyne imaging. The results showed a small contribution to total absorption from thin-film interfaces, as compared to HfO2 film material. The relevance of obtained absorption data to coating near-ultraviolet, nanosecond-pulse laser damage was verified by measuring the damage threshold and characterizing damage morphology. The results of this study revealed a higher damage resistance in the seven-layer coating as compared to the single-layer HfO2 film in both sputtered and evaporated coatings. Here, the results are explained through the similarity of interfacial film structure with structure formed during the co-deposition of HfO2 and SiO2 materials.« less