Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Surface chemical reactions I
O 49.8: Talk
Wednesday, March 24, 2010, 12:15–12:30, H42
High pressure behavior of Au/TiOx/Pt(111) model catalysts — Luca Artiglia1, Gaetano Granozzi1, •Heinrich Hartmann2, Thomas Diemant2, Joachim Bansmann2, and R. Jürgen Behm2 — 1Department of Chemical Sciences, via Marzolo 1, University of Padova, Italy — 2Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany
In an effort to bridge the pressure gap between model and realistic catalytic processes, three different ultrathin TiOx on Pt(111) films have been prepared and investigated in-situ using XPS, LEED and IRAS to determine their stability in pure CO and CO/O2 (1:1) at pressures up to 100 mbar. Two of the TiOx films consist of reduced phases with and without a long range order of defects, the third film is a fully oxidized TiO2 phase.
All three TiOx phases were stable in a reducing CO atmosphere at RT. In a CO/O2 (1:1) mixture, only the fully oxidized phase showed no structural and electronic changes. The reduced phases underwent a process of oxidative surface restructuring with a partial dewetting of the Pt(111) substrate.
The TiOx/Pt(111) films were used as substrates to deposit Au nanoparticles (1-6 nm) with surface morphologies particular to each TiOx phase. IRAS measurements on these Au/TiOx/Pt(111) model catalysts showed, that the size of the Au nanoparticles (itself dependent on the morphology of the underlying TiOx phase) plays a major role for the adsorption of CO, while the oxidation state of the oxide support is less relevant.