Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 4: Heterogeneous catalysis I

O 4.6: Talk

Monday, March 22, 2010, 12:30–12:45, H33

Oxidation of carbon monoxide on Au/ZnO nanoparticles: an infrared spectroscopy study — •Heshmat Noei¹, Martin Muhler¹, and Yuemin Wang^1,2 — ¹Lehrstuhl für Technische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany — ²Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, 44801 Bochum, Germany

Recently, supported gold nanoparticles have attracted enormous attention due to their unique catalytic properties for a number of chemical reactions including CO oxidation at low temperatures. In this contribution the catalytic reactivity of different ZnO-supported Au nanoparticles was studied systematically by ultra-high vacuum FTIR spectroscopy (UHV-FTIRS). Exposing negatively charged Au nanoparticles to CO at 110 K leads to the appearance of two C-O stretching bands at 2180 and 2066 cm⁻¹, which are assigned to CO species adsorbed on ZnO and Au surfaces, respectively. On oxidized Au/ZnO (with Au⁰) the IR band for CO adsorption on ZnO is observed at 2183 cm⁻¹, while two new C-O bands show up at 2105 and 2112 cm⁻¹, which are attributed to the CO species adsorbed on Au/ZnO interface and Au particles, respectively. After further exposing the reduced and oxidized Au/ZnO nanopartcles to oxygen at 110 K, CO oxidation occurs yielding physisorbed CO₂ and carbonate species. It was found that the reduced surfaces favour CO₂ production, whereas on the oxidized surfaces carbonate species are preferentially formed. The catalytic mechanisms of low temperature CO oxidation will be discussed in details.