Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 15: Heterogeneous catalysis I
O 15.6: Talk
Monday, March 26, 2012, 17:15–17:30, MA 042
First-principles kinetic Monte Carlo simulations of CO oxidation at Pd(100): Surface oxide or metal? Both! — •Max J. Hoffmann1, Matthias Scheffler2, and Karsten Reuter1 — 1TU München, Germany — 2Fritz-Haber-Institut, Berlin, Germany
CO oxidation at Palladium model catalysts is an evergreen in the quest to establish an atomic-scale understanding of heterogeneous catalytic processes and the relation between atomistic structure and catalytic activity. Notwithstanding and despite numerous experiments, the character of the active surface above Pd(100) under ambient reaction conditions remains heavily debated [1]. The pristine metal surface, a thin surface oxide layer, and bulk palladium oxide have each been suggested to be present and responsible for the catalytic activity.
Contributing to this we perform first-principles kinetic Monte Carlo (1p-kMC) simulations for each of these phases as a function of temperature and partial pressures. Next to obtaining their inherent catalytic activities at steady-state, we can use the determined surface coverages to infer on the stability ranges of the different phases. Intriguingly, this indicates an overlap of the stability regimes of pristine and oxidized Pd(100), which could be underlying the experimentally observed bistability switching between different reaction kinetics.[2]
[1] Gao et al., J. Phys. Chem. C, 114, 6874 (2010).
[2] Frenken et al., Topics Catal. 36, 43 (2005).