The surface oxide as a source of oxygen on Rh(111)

E. Lundgren1, J. Gustafson1, A. Resta1, J. Weissenrieder1, A. Mikkelsen1, J.N. Andersen1, L. Köhler2, G. Kresse2, J. Klikovits3, A. Biedermann3, M. Schmid3, P. Varga3

1 Department of Synchrotron Radiation Research, Institute of Physics, Lund University, S-22100 Lund, Sweden
2 Institut f. Materialphysik and Centre for Computational Materials Science, Universität Wien, 1090 Wien, Austria
3 Institut für Allgemeine Physik, Technische Universität Wien, 1040 Wien, Austria

J. Electron Spectrosc. Relat. Phen. 144-147 (2005) 367-372

The reduction of a thin surface oxide on the Rh(111) surface by CO is studied in-situ by photoemission spectroscopy, scanning tunneling microscopy, and density functional theory. CO molecules are found not to adsorb on the surface oxide at a sample temperature of 100 K, in contrast to on the clean and chemisorbed oxygen covered surface. Despite this behavior, the surface oxide may still be reduced by CO, albeit in a significantly different fashion as compared to the reduction of a phase containing only chemisorbed on-surface oxygen. The experimental observations combined with theoretical considerations concerning the stability of the surface oxide result in a model of the reduction process at these pressures suggesting that the surface oxide behaves as a source of oxygen for the CO-oxidation reaction.

Corresponding author: E. Lundgren. Reprints also available from M. Schmid (schmid< encoded email address >).

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