Electronic and Geometric Structure of Ce3+ Forming Under Reducing Conditions in Shaped Ceria Nanoparticles Promoted by Platinum

The structure of Ce3+, which is responsible for the low-temperature oxygen storage capacity of ceria, was determined by high-energy-resolution fluorescence detected X-ray absorption spectroscopy at the Ce L3 and L1 edges. Well-defined ceria nanoparticles (rods, truncated octahedra, and cubes) were s...

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Published inJournal of physical chemistry. C Vol. 118; no. 4; pp. 1974 - 1982
Main Authors Safonova, O. V, Guda, A. A, Paun, C, Smolentsev, N, Abdala, P. M, Smolentsev, G, Nachtegaal, M, Szlachetko, J, Soldatov, M. A, Soldatov, A. V, van Bokhoven, J. A
Format Journal Article
LanguageEnglish
Published American Chemical Society 30.01.2014
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Summary:The structure of Ce3+, which is responsible for the low-temperature oxygen storage capacity of ceria, was determined by high-energy-resolution fluorescence detected X-ray absorption spectroscopy at the Ce L3 and L1 edges. Well-defined ceria nanoparticles (rods, truncated octahedra, and cubes) were synthesized hydrothermally and promoted by platinum nanoparticles. The electronic structure of Ce3+ does not depend significantly on the nature of the exposed crystallographic planes of CeO2 particles; it does, however, differ from the electronic structure of known stable compounds containing Ce3+ ions, such as CeAlO3, Ce(NO3)3·6H2O, and Ce2Zr2O7. Theoretical simulation of Ce L1 and L3 X-ray absorption spectra, quantitative analysis of the oxygen storage capacity, and X-ray diffraction data suggest that Ce3+ ions form both at the surface and in the near-surface layer. Surface and bulk Ce3+ ions are characterized by elongated Ce–O distances in the first coordination shell and almost the same Ce–Ce distances in the second coordination shell with respect to Ce4+ in stoichiometric CeO2. Ce3+ ions on the surface of the nanoparticles surface may have a smaller number of oxygen neighbors (as low as six), while in the near-surface layer they tend to have an 8-fold coordination, thus producing oxygen deficit structures similar to Ce11O20.
ISSN:1932-7447
1932-7455
DOI:10.1021/jp409571b