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O: Fachverband Oberflächenphysik
O 58: Surface chemical reactions II
O 58.4: Talk
Wednesday, March 24, 2010, 15:45–16:00, H42
High pressure XPS on supported planar model and powder Au/TiO2 catalysts in the presence of reactive gases — •Joachim Bansmann1, Yvonne Denkwitz1, Stefan Kielbassa1, Birgit Schumacher1, R. Jürgen Behm1, Peter Schnörch2, Elaine Vass2, Michael Hävecker2, Axel Knop-Gericke2, and Robert Schlögl2 — 1Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm — 2Dept. Inorganic Chemistry, Fritz-Haber-Institut, D-14195 Berlin
The interaction of pre-conditioned, planar Au/TiO2(110) model and dispersed Au/TiO2 catalysts with O2, CO and CO/O2 atmospheres at sub-millibar pressures was investigated by in-situ X-ray photoelectron spectroscopy at BESSY. Measurements in different reaction atmospheres showed that Au is present as metallic Au nanoparticles on both types of catalysts. There was no evidence for positively charged Auδ + species, neither during nor after exposure to the respective atmospheres. The TiO2(110) substrate, on the other hand, changed its chemical, electronic and electric properties during these treatments, which results in variable shift of the substrate-related binding energy of the valence band and the Ti(2p) core levels. Whereas a detailed analysis in the case of powder catalysts was largely limited by severe charging effects, we could follow the chemically-induced variations in the electronic states of the planar Au/TiO2(110) model catalysts.