The full catalytic cycle that involves the oxidation of two CO molecules is investigated here by using periodic density functional calculations. To simulate the nature of Fe(OH)x/Pt nanoparticles, three possible structural models, i.e., Fe(OH)x/Pt(111), Fe(OH)x/Pt(332) and Fe(OH)x/Pt(322), are built. We demonstrate that Fe(iii)–OH–Pt stepped sites readily react with CO adsorbed nearby to directly yield CO2 and simultaneously produce coordinatively unsaturated iron sites for O2 activation. By contrast, the created interfacial vacancy on Fe(OH)x/Pt(111) prefers to adsorb CO rather than O2, thus inhabiting the catalytic cycles of CO oxidation. We suggest that such structure sensitivity can be understood in terms of the bond strengths of Fe(iii)–OH.
Structure sensitivity in oxide catalysis: First-principles kinetic Monte Carlo simulations for CO oxidation at RuO2(111)
