CO oxidation on Pd(100) vs. PdO(sqrt5xsqrt5)R27^o: First-Principles Kinetic Phase Diagrams and Bistability Conditions

Abstract

We present first-principles kinetic Monte Carlo (1p-kMC) simulations addressing the CO oxidation reaction at Pd(100) for gas-phase conditions ranging from ultra-high vacuum (UHV) to ambient pressures and elevated temperatures. For the latter technologically relevant regime there is a long-standing debate regarding the nature of the active surface. The pristine metallic surface, an ultra-thin (sqrt5xsqrt5)R27^o PdO(101) surface oxide, and thicker oxide layers have each been suggested as the active state. We investigate these hypotheses with 1p-kMC simulations focusing on either the Pd(100) surface or the PdO(101) surface oxide and intriguingly obtain a range of (T, p)-conditions where both terminations appear metastable. The predicted bistability regime nicely ties in with oscillatory behavior reported experimentally by Hendriksen and coworkers [Catal. Today 105, 234 (2005)]. Within this regime we find that both surface terminations exhibit very similar intrinsic reactivity, which puts doubts on attempts to assign the catalytic function to just one active state.

25 pages, 6 figures

References in corpus (4)

• First-principles statistical mechanics study of the stability of a sub-nanometer thin surface oxide in reactive environments: CO oxidation at Pd(100)
• CO oxidation at Pd(100): A first-principles constrained thermodynamics study
• CO oxidation on Pd(100) at technologically relevant pressure conditions: A first-principles kinetic Monte Carlo study
• On the accuracy of first-principles lateral interactions: Oxygen at Pd(100)

Cited by in corpus (3)

• A Practical Guide to Surface Kinetic Monte Carlo Simulations
• Multi-Lattice Kinetic Monte Carlo Simulations from First-Principles: Reduction of the Pd(100) Surface Oxide by CO
• Structure Sensitivity in Oxide Catalysis: First-Principles Kinetic Monte Carlo Simulations for CO Oxidation at RuO${}_2$(111)