Regensburg 2004 – scientific programme

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O: Oberflächenphysik

O 26: Adsorption an Oberflächen II

O 26.9: Talk

Tuesday, March 9, 2004, 17:45–18:00, H45

Coadsorption of H and CO on Pd(210) — •Christian Mosch, Markus Lischka, and Axel Groß — Physics-Department, Technical University of Munich, D-85747 Garching, Germany

The study of the interaction of molecules with stepped surfaces is of importance in order to close the structure gap between surface science and heterogeneous catalysis. We have focused on the adsorption of hydrogen [1,2] and CO on Pd(210) by performing density functional theory (DFT) calculations within the generalized gradient approximation. The (210) surface can be regarded as being built up by small (100) terraces. CO is known to adsorb on Pd(100) in an upright fashion at the bridge position [3,4]. On Pd(210), there are two inequivalent bridge positions. And indeed, we find a relatively small corrugation in the CO adsorption energies with the two bridge sites being energetically almost degenerate. CO is furthermore known as a strong poison in heterogeneous catalysis. We have therefore also addressed the coadsorption of CO with atomic hydrogen. There is a strong inhibition of the hydrogen adsorption due to the presence of CO which is analyzed in terms of the electronic structure of the adsorbate system.

[1] P.K. Schmidt et al., Phys. Rev. Lett. 87, 096103 (2001).

[2] M. Lischka and A. Groß, Phys. Rev. B 65, 075420 (2002)

[3] A. M. Bradshaw and F. M. Hoffmann, Surf. Sci. 72, 513 (1978).

[4] A. Eichler and J. Hafner, Phys. Rev. B 57, 10110 (1998).