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Abstract

Microkinetic modeling of surface chemical reactions still relies heavily on the mean-field based rate
equation approach. This approach is expected to be most accurate for systems without appreciable
lateral interactions among the adsorbed chemicals, and there in particular for the uniform adlayers
resulting in poisoned regimes with predominant coverage of one species. Using first-principles
kinetic Monte Carlo simulations and the CO oxidation at RuO2(110) as a showcase, we demonstrate
that even in this limit mean-field rate equations fail to predict the catalytic activity by orders
of magnitude. This deficiency is traced back to the inability to account for the vacancy pair formation
that is kinetically driven by the ongoing reactions.