Redox Properties of Water on the Oxidized and Reduced Surfaces of CeO{sub 2} (111)
We present x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) results probing the surface chemistry of water on the oxidized and reduced surfaces of a 500 {angstrom} epitaxial CeO{sub 2} (111) film grown on yttria-stabilized ZrO{sub 2} (111). Oxidation with O{sub 2} at 773 K under UHV conditions was sufficient to generate XPS spectra reflective of fully oxidized CeO{sub 2} (111). Surface reduction was carried out by annealing in UHV between 773 and 973 K, and the level of reduction was quantified using changes in the Ce3d{sub 3/2} 4f{sup 0} photoemission peak at 917 eV which results primarily from Ce{sup 4+} sites. As expected, the level of surface reduction (generation of Ce{sup 3+} sites) increased with increasing temperature. These Ce{sup 3+} sites were primarily in the first layer based on the fact that exposure of the film to O{sub 2} at RT resulted in nearly complete conversion of Ce{sup 3+} to Ce{sup 4+}. Annealing at 773 K led to a surface in which approximately 40% of the surface Ce{sup 4+} sites were reduced to Ce{sup 3+}, whereas annealing at higher temperatures led to more substantial reduction of the first layer along with some subsurface reduction that was not reoxidized by RT exposure to O{sub 2}.
- Research Organization:
- Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Laboratory (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15003544
- Report Number(s):
- PNNL-SA-37912; SUSCAS; 6694; KC0302010; TRN: US200502%%58
- Journal Information:
- Surface Science, Vol. 526, Issue 1-2; Other Information: PBD: 20 Feb 2003; ISSN 0039-6028
- Country of Publication:
- United States
- Language:
- English
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