AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThA

Paper SS1-ThA2
The Hydrogen Cycle on the CeO@sub 2@ <111> Surface

Thursday, November 16, 2006, 2:20 pm, Room 2002

Session: Reactivity of Oxide Surfaces II
Presenter: A.S. Foster, Helsinki University of Technology, Finland
Authors: M. Watkins, University College London, UK
A.S. Foster, Helsinki University of Technology, Finland
A.L. Shluger, University College London, UK
Correspondent: Click to Email
The ability of Cerium atoms to exist in varying charge states permits facile surface oxidation/reduction allowing ceria to mediate oxygen concentration when part of a mixed metal oxide catalyst. There is an extensive literature on the reduction/oxidation behaviour, however, experimental conditions and uncertainties in sample preparation make interpretation of experimental data difficult. We present density functional calculations implementing the generalized gradient approximation (GGA) and on site coulomb interactions (GGA+U) on the most stable surface of Ceria, specifically focusing on its interactions with hydrogen and water. Our calculations allow us to consider the process of surface reduction and the probable state of lightly reduced surfaces in the presence of water, allowing insight into surface processes in a variety of conditions. Several interesting properties of the Ceria surface are brought to the fore - the dissociation of water molecules on the ideal surface, the rapid dissociation of water at vacancy sites and the strongly exothermic dissociation of H@sub 2@ on the ideal surface. These results have strong implications for the interpretation of experimental data, and the construction of reaction schemes for this technologically important metal oxide surface.