Title

Cerium LIII-edge EXAFS Investigation of the Structure of Crystalline and Amorphous Cerium Oxides

Abstract

Cerium oxide solid samples were prepared via precipitation from aqueous solution of hydrous cerium(III) nitrate in the presence of different percentages of H 2O2 to increase the potential for cerium oxide precipitates to function as oxygen traps for fuel cells. X-ray absorption spectroscopy at the Ce LIII edge was applied for the characterization of crystalline anhydrous CeO2, nanocrystalline hydrous CeO2, nanocrystalline CeO2 sample I precipitated in the presence of H 2, and an amorphous CeO2 sample II precipitated at a higher H 2O2 concentration. XANES for cerium oxides did not indicate a broad variation in cerium valence state in the precipitated samples as compared to anhydrous CeO2. Furthermore, XANES analysis revealed a decrease in the intensity of the white line peaks for the precipitated samples relative to those in anhydrous CeO2. Hydrogen peroxide reduced the precipitate's particle size and bulk crystallinity. Growth in the coordination number of the first, Ce-O, shell was observed with an increased bond distance RCe-O in hydrous and precipitated CeO2 samples. However, the coordination numbers of the third, Ce-Ce and the sixth, Ce-O, shells were reduced in comparison with anhydrous CeO2.

Meeting Name

228th ACS National Meeting (2004: Aug. 22-26; Philadelphia, PA)

Department(s)

Chemistry

Sponsor(s)

American Chemical Society (ACS)

International Standard Serial Number (ISSN)

657727

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2004 American Chemical Society (ACS), All rights reserved.

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