Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 18: Adsorption an Oberflächen I

O 18.1: Vortrag

Dienstag, 9. März 2004, 11:15–11:30, H38

Composition of the surface oxide on Pd(100) in an O₂ and CO environment — •Jutta Rogal, Karsten Reuter, and Matthias Scheffler — Fritz-Haber-Institut der MPG, Berlin,Germany

The oxidation of the Pd(100) surface leads to a (√5× √5)R27^∘ surface oxide structure, which was recently identified to be essentially a PdO(101) overlayer on Pd(100)[1]. In thermodynamic equilibrium with an O₂ gas phase this surface oxide represents the most stable phase over a wide range of environmental conditions, suggesting that the surface oxide may play some role in the catalytic oxidation of CO on the Pd(100) surface.

To get a first insight into this catalytic reaction we investigate the structure and composition of the surface oxide in equilibrium with an arbitrary O₂ and CO gas environment using density-functional theory and No-dqconstrainedNo-dq atomistic thermodynamics[2]. Studying the simultaneous adsorption of CO and O we arrive at a (T,p)-phase diagram of the stable structures, and discuss possible kinetic effects due to the ongoing reaction.

[1] M. Todorova et al., Surf. Sci. 541, 101-112 (2003)

[2] K. Reuter and M. Scheffler, Phys. Rev. B 68, 045407 (2003)