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O: Oberflächenphysik
O 26: Postersitzung (Rastersondentechniken, Nanostrukturen, Teilchen und Cluster, Methodisches, Oxide und Isolatoren, Grenzfl
äche fest-flüssig, Struktur und Dynamik reiner Oberfl
ächen, Oberfl
ächenreaktionen, Zeitaufg. Spektroskopie, Phasenüberg
änge
O 26.70: Poster
Mittwoch, 13. März 2002, 14:30–17:30, Bereich C
The Complex Redox Chemistry of the RuO2(110) surface: Theory and Experiment — •Ari Seitsonen1, Young Dok Kim2, Stefan Wendt2, Marcus Knapp2,3, Edvin Lundgren4, Michael Schmid4, Peter Varga4, and Herbert Over2,1,3 — 1MPI für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart — 2Dept. Phys. Chemie, Fritz-Haber Institut der MPG, Faradayweg 4-6, 14195 Berlin — 3Dept. Phys. Chemie, JLU Giessen, Heinrich-Buff-Ring 58, 35392 Giessen — 4Inst. für Allgemeine Physik, TU Wien, Wiedner Hauptstr. 8-10, A-1040 Wien, Austria
RuO2(110) is mildly and heavily reduced by CO exposure when the reaction temperature is below 400 K and above 500 K, respectively. The restoration of the reduced RuO2(110) surface was investigated by LEED and AES. CO molecules adsorb over the under-coordinated Ru atoms and recombine with the under-coordinated lattice O atoms on the RuO2(110) surface. The initial conversion probability for this process is as high as 80 by the removal of bridging O atoms. A (completely) mildly reduced surface is inactive in oxidizing CO below 450 K. However, temperature treatment (= 550 K) or oxygen exposure at room temperature is able to reactivate the mildly reduced surface. Heavy reduction of RuO2(110) leads to a roughening of the surface, which is partly restored by annealing at 700 ... 800 K. The activation barriers of various reaction pathways are determined by state-of-the-art DFT calculations and compared with experiments.