Monte Carlo simulation of CO and O coadsorption and reaction on Pt(1 1 1)

Abstract

Dissociative oxygen adsorption, CO adsorption on the oxygen-covered Pt(1 1 1) surface, formation and stability of the p(2 × 2) structure of adsorbed oxygen and of O–CO coadsorbed layers, and reaction kinetics have been simulated by a refined Monte Carlo method. Results of the simulations are in good agreement with experiments, which suggests validity of the concepts of the precursor states in the dissociative adsorption, indirect lateral interaction between adsorbed particles, and reveals important role of mobility of the species in formation of film structures and in reaction between adsorbed CO molecules and O atoms. A new model of catalytic CO oxidation reaction, in which only oxygen atoms in hcp-type threefold adsorption sites on the Pt(1 1 1) surface are chemically active, is suggested. Within this model, the TPD (temperature programmed desorption) spectra of the coadsorbed CO–O films, which represent the rate of CO oxidation, do resemble experimental data for CO adsorption on a perfectly ordered p(2 × 2) oxygen film as well as on the oxygen layer with domain walls.