Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 10: Adsorption an Oberfl
ächen (I)
O 10.10: Vortrag
Montag, 26. März 2001, 18:30–18:45, C
Chemical reacticity of palladium-vanadium binary alloy surfaces — •Robin Hirschl, Andreas Eichler, and Jürgen Hafner — Institut für Materialphysik and Center for Computational Materials Science, Universität Wien, Sensengasse 8/12, A-1090 Wien, Austria
We study the adsorption properties of palladium-vanadium (111) alloy surfaces with ab-initio density functional calculations. The code used is the Vienna Ab initio Simulation Package (VASP), which is based on a plane wave basis set and PAW pseudo-potentials. The test molecules investigated are CO and H2.
Compared to the clean Pd (111) surface the adsorption energies for both molecules decrease up to 30% by incorporating V impurities sub surface. Investigation of the local adsorption properties for CO show that the influence of V atoms differs qualitatively depending on the concentration. Adsorption energy differences between clean and alloyed surfaces are in good agreement with experimental TPD results. In the case of H2 adsorption, we could identify a physisorbed precursor state over the alloyed surface (in agreement with experimental predictions), while adsorption on the clean metal surface is dominated by a steering mechanism.