Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 28: Heterogeneous catalysis II

O 28.5: Talk

Tuesday, March 27, 2012, 11:30–11:45, MA 042

HR-EELS studies on zinc oxide powder samples — •Sebastian Frey, Martin Kroll, and Ulrich Köhler — Ruhr-Universität, Bochum, Deutschland

High resolution electron energy loss spectroscopy is a useful tool in heterogeneous catalysis as it provides information about vibration states of adsorbates. With this, not only the adsorbed species can be identified, but also their orientation can be determined. In methanol synthesis HR-EELS is successfully applied to doped oxide single crystals [1] while studies on oxide powders, which are more similar to real catalysts, rely on infrared spectroscopy (FTIRS, [2]) due to their low conductivity.

However, with a thoroughly preparation it is possible to sediment a thin powder layer on a gold plate substrate. This avoids the conductivity problem and enables HR-EELS studies also on powders. Results show a distinct signal of Fuchs-Kliewer phonons and their multiples decreasing during adsorption which is comparable to ZnO single crystal samples. Further measurements contain CO, CO2, Methanol and other gases.

[1] Y. Wang et al., Angew. Chem. Int. Ed., 46, 5624-5627 (2007)

[2] H. Noei et al., Appl. Catalysis A, 391, 31-35 (2011)