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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.77: Poster

Wednesday, March 28, 2007, 17:00–19:30, Poster C

CO oxidation measurements on Au/TiO₂ model catalysts — •Stefan Kielbassa, Joachim Bansmann, and Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University

Au nanoparticles on metal oxide supports exhibit a high catalytic activity for numerous reactions, e.g., the low temperature CO oxidation. It was found, that the activity is not only very sensitive to the size and the shape of the Au particles, but also to the chemical composition of the support. Especially reducible metal oxides, like TiO₂, are known to increase the catalytic activity and thus, they are not only passive spectators.

Planar model catalysts are ideally suited to investigate the influence of structural properties on the catalytic activity by varying the numbers of defects, steps and kinks on the substrate surface. Therefore, different types of planar titania surfaces, from well-ordered single crystal via epitaxially ordered to polycrystalline films, have been prepared and their influence on the CO oxidation activity of Au/TiO₂ model catalysts was studied using a micro-flow reactor attached to the UHV preparation chamber. We found, that significant differences in the catalytic activity can be observed with respect to the surface structure of the support. The results will be discussed with respect to activity data on model catalysts presented previously.