Reaction-path switching induced by spatial-distribution change of reactants: CO oxidation on Pt(111)

The mechanism of carbon monoxide oxidation on oxygen covered Pt(111) surfaces during CO exposure was studied using time-resolved near edge x-ray absorption fine structure spectroscopy. A switching of reaction path in CO oxidation reaction was caused by the CO adsorption induced two dimensional condensation of O atoms. Monte Carlo simulations and in situ monitoring of reaction kinetics revealed that CO coadsorption played a role of inducing change in spatial distribution of O atoms. The results demonstrate that effects of long-range interactions and consequent dynamic spatial-distribution changes of the reactants are of importance for understanding the kinetics in the reaction systems deviated from the conventional Langmuir-Hinshelwood kinetics.