Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 9: Adsorption an Oberfl
ächen I

O 9.2: Vortrag

Montag, 24. März 2003, 15:15–15:30, FOE/ANOR

Ab initio investigation of the adsorption of atoms and small molecules on the polar ZnO(0001) surfaces — •Karin Fink — Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum

The system Cu/ZnO is of great importance in hetereogeneous catalysis, especially for the methanol sythesis. Therefore it is necessary to get detailed information on the interaction between the different surface planes of ZnO and Cu atoms or small Cu particles and the adsorption of small molecules on ZnO.

The main problem for the description of the adsorption process is the design of appropiate cluster models for the ZnO(0001) and ZnO(000-1) surfaces. For electrostatic reasons these polar surfaces should not be stable without geometrical or electronic reconstructions. For ZnO the form of these reconstructions is still under discussion.

We have designed cluster models representing different stabilization schemes of the polar surfaces (defects, metallization of the surfaces, H adsorption) and compared the binding energy of CO for the different models. The comparison with the experimental adsorption energies leeds to a detailed understanding of the stabilization of the polar surfaces.

At the moment we investigate the adsorption of several species involved in methanol sythesis such as CO₂, CO₂⁻, HCOO⁻.