Title

Density functional theory study of water adsorption at reduced and stoichiometric ceria (111) surfaces

Authors

Authors

S. Kumar;P. K. Schelling

Comments

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Abbreviated Journal Title

J. Chem. Phys.

Keywords

ELECTRONIC-STRUCTURE; MOLECULAR-DYNAMICS; CEO2; H2O; PRINCIPLES; CEO2(111); CHEMISTRY; DIOXIDE; SOLIDS; CO; Physics, Atomic, Molecular & Chemical

Abstract

We study the structure and energetics of water molecules adsorbed at ceria (111) surfaces for 0.5 and 1.0 ML coverages using density functional theory. The results of this study provide a theoretical framework for interpreting recent experimental results on the redox properties of water at ceria (111) surfaces. In particular, we have computed the structure and energetics of various absorption geometries at the stoichiometric ceria (111) surface. We find that single hydrogen bonds between the water and the oxide surface are favored in all cases. At stoichiometric surfaces, the water adsorption energy depends rather weakly on coverage. We predict that the observed coverage dependence of the water adsorption energy at stoichiometric surfaces is likely the result of dipole-dipole interactions between adsorbed water molecules. When oxygen vacancies are introduced in various surface layers, water molecules are attracted more strongly to the surface. We find that it is very slightly energetically favorable for adsorbed water to oxidized the reduced (111) surface with the evolution of H-2. In the event that water does not oxidize the surface, we predict that the effective attractive water-vacancy interaction will result in a significant enhancement of the vacancy concentration at the surface in agreement with experimental observations. Finally, we present our results in the context of recent experimental and theoretical studies of vacancy clustering at the (111) ceria surface. (c) 2006 American Institute of Physics.

Journal Title

Journal of Chemical Physics

Volume

125

Issue/Number

20

Publication Date

1-1-2006

Document Type

Article

Language

English

First Page

8

WOS Identifier

WOS:000242408100041

ISSN

0021-9606

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