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O: Oberflächenphysik

O 28: Surface reactions II

O 28.1: Vortrag

Dienstag, 28. März 2006, 15:45–16:00, WIL C207

CO-Oxidation measurements on Au/TiO₂ model catalysts — •S. Kielbassa¹, J. Bansmann¹, F. Weigl², H.G. Boyen², P. Ziemann², and R.J. Behm¹ — ¹Dept. of Surface Chemistry and Catalysis, University of Ulm — ²Dept. of Solid State Physics, University of Ulm

Model catalysts with tuneable particle size and distance parameters on flat surfaces open new opportunities for studying the influence of particle sizes and separations on the catalytic activity. However, the overall small active surface, approximately 1:500^th of 1mg of a comparable powder catalyst, results in a very low total product conversion which is difficult to detect, especially in higher pressure regimes ( 1atm). Our model catalysts consist of Au particles with defined particle sizes (1-5nm) and separations (30-100nm) prepared by a micellar approach on flat TiO₂(110) single crystal surfaces. For the catalytic measurements, we use a novel design of a reactor with a very small volume ( 0.003ml) and constant gas-flow ( 0.0005ml) to detect the oxidation of CO. The reactor is situated in the load-lock of a UHV-chamber, which gives us the opportunity to characterize the samples in-situ with AFM and XPS without moving them through air. Results of the influence of particle sizes and separations on the activity are discussed.