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Title: Synthesis, Optical, and Photocatalytic Properties of Cobalt Mixed-Metal Spinel Oxides Co(Al1-xGax)2O4

Authors:
; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
NREL's Laboratory Directed Research and Development (LDRD)
Contributing Org.:
University of Colorado, Boulder, Colorado
OSTI Identifier:
1220654
Report Number(s):
NREL/JA-5900-63353
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Materials Chemistry A; Journal Volume: 3; Journal Issue: 15
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 77 NANOSCIENCE AND NANOTECHNOLOGY

Citation Formats

Lee, K., Ruddy, D. A., Dukovic, G., and Neale, N. R.. Synthesis, Optical, and Photocatalytic Properties of Cobalt Mixed-Metal Spinel Oxides Co(Al1-xGax)2O4. United States: N. p., 2015. Web. doi:10.1039/C4TA06690A.
Lee, K., Ruddy, D. A., Dukovic, G., & Neale, N. R.. Synthesis, Optical, and Photocatalytic Properties of Cobalt Mixed-Metal Spinel Oxides Co(Al1-xGax)2O4. United States. doi:10.1039/C4TA06690A.
Lee, K., Ruddy, D. A., Dukovic, G., and Neale, N. R.. Tue . "Synthesis, Optical, and Photocatalytic Properties of Cobalt Mixed-Metal Spinel Oxides Co(Al1-xGax)2O4". United States. doi:10.1039/C4TA06690A.
@article{osti_1220654,
title = {Synthesis, Optical, and Photocatalytic Properties of Cobalt Mixed-Metal Spinel Oxides Co(Al1-xGax)2O4},
author = {Lee, K. and Ruddy, D. A. and Dukovic, G. and Neale, N. R.},
abstractNote = {},
doi = {10.1039/C4TA06690A},
journal = {Journal of Materials Chemistry A},
number = 15,
volume = 3,
place = {United States},
year = {Tue Apr 21 00:00:00 EDT 2015},
month = {Tue Apr 21 00:00:00 EDT 2015}
}
  • Systems containing MgO and Al/sub 2/O/sub 3/ showed maximum activity for hydrocarbon synthesis from CO and H/sub 2/ among Co-catalysts, where cobalt was applied to metal oxides (groups II-III). When these oxides are heated above 400/sup 0/C cobalt ions penetrate the oxide lattice to form spinel structures. The inclusion of cobalt cations into these spinel structures formed when Co-Al/sub 2/O/sub 3/ and Co-MgO catalysts are heated in air, apparently, affects their properties. In this study catalysts containing cobalt-aluminum spinels are examined as carriers during the synthesis of hydrocarbons from CO and H/sub 2/. 9 references, 2 figures, 5 tables.
  • Ferritic stainless steels are promising candidates for interconnect applications in low- and mid-temperature solid oxide fuel cells (SOFCs). A couple of issues however remain for the particular application, including the chromium poisoning due to chromia evaporation, and long-term surface and electrical stability of the scale grown on these steels. Application of a manganese colbaltite spinel protection layer on the steels appears to be an effective approach to solve the issues. For an optimized performance, Mn{sub 1+x}Co{sub 2-x}O{sub 4} (-1 {le} x {le} 2) spinels were investigated against properties relative for protection coating applications on ferritic SOFC interconnects. Overall it appearsmore » that the spinels with x around 0.5 demonstrate a good CTE match to ceramic cell components, a relative high electrical conductivity, and a good thermal stability up to 1,250 C. This was confirmed by a long-term test on the Mn{sub 1.5}Co{sub 1.5}O{sub 4} protection layer that was thermally grown on Crofer22 APU, indicating the spinel protection layer not only significantly decreased the contact resistance between a LSF cathode and the stainless steel interconnects, but also inhibited the sub-scale growth on the stainless steels.« less
  • New layered Co oxides of nominal formula Sr{sub 2}(Ln{sub 0.8}Ca{sub 0.2})Co{sub 2}O{sub 6} (Ln = Sm, Eu, Gd, Tb, Dy, Ho, and Y) are reported. Single-phase polycrystalline samples were obtained at compositions Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Co{sub 2}{sup 2.5+}O{sub 6{minus}{delta}} (0.2 {le} x {le} 0.5; 0 {le} {delta} {le} 0.24), Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Co{sub 2}{sup 3.4+}O{sub 6+{delta}{prime}} (0.2 {le} x {le} 0.5; 0.62 {le} {delta}{prime} {le} 0.79), and Sr{sub 2}Dy{sub 0.8}Ca{sub 0.2}Co{sub 2}O{sub 6.09}. Powder X-ray and neutron diffraction, thermogravimetric analysis, magnetic susceptibility, and ac resistivity measurements were used to characterize the samples. The tetragonal unit cell for Sr{sub 2}Y{sub 0.8}Ca{submore » 0.2}Co{sub 2}O{sub 6.00} (I4/mmm; a = 3.82765(6) {angstrom}, and c = 19.5795(3) {angstrom}) is comparable to that of the double layer superconducting copper oxide La{sub 2{minus}x}Sr{sub x}CaCu{sub 2}O{sub 6}. A long-range antiferromagnetic (AF) ordered state below about 300 K is found for Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Co{sub x}{sup 2.5+}O{sub 6{minus}{delta}}, and a magnetically glassy state below about 40 K for the oxidized AF phases. All materials are electrically insulating.« less
  • No abstract prepared.
  • Li{sub 2}Mn{sub 4}O{sub 9{minus}{delta}} spinel oxides with 0.36 < {delta} < 0.46 were synthesized by oxidation of aqueous Mn{sup 2+} with hydrogen peroxide or lithium peroxide in the presence of lithium carbonate or lithium hydroxide followed by firing the precursor in air at 300--400 C. Li{sub 2}Mn{sub 4}O{sub 9{minus}{delta}} spinel is metastable and disproportionates at about 500 C to give a lithium-rich spinel Li{sub 1{minus}x}Mn{sub 2{minus}x}O{sub 4+{delta}} and Mn{sub 2}O{sub 3}. The disproportionation temperature and the amount of Mn{sub 2}O{sub 3} impurity formed depended on the synthesis procedure and raw materials used. Use of lithium peroxide and lithium hydroxide inmore » the solution-based oxidation procedure produced the least amount of Mn{sub 2}O{sub 3} impurity at intermediate temperatures. However, the value of x in the lithium-rich spinel Li{sub 1+x}Mn{sub 2{minus}x}O{sub 4+{delta}} decreased with a further increase in firing temperature, and the stoichiometric spinel LiMn{sub 2}O{sub 4} without Mn{sub 2}O{sub 3} impurity was formed at 800 C. Phase analysis as a function of firing temperature for a wider range of Li/Mn ratios in the system Li{sub y}Mn{sub 3{minus}y}O{sub 4+{delta}} (0.7 {le} y {le} 1.33) also revealed that single-phase spinel could be formed for the entire firing temperature range 300 {le} T {le} 800 C only for a narrow value of 1.05 {le} y {le} 1.25. The lithium-intercalation properties of the metastable Li{sub 2}Mn{sub 4}O{sub 9{minus}{delta}} spinel were influenced by the firing temperature. A Li{sub 2}Mn{sub 4}O{sub 9{minus}{delta}} sample formed at an optimum temperature of 400 C showed a capacity of 130 mAh/g in the range 3.8--2.0 V with excellent cyclability.« less