Mechanisms and energetics of CO oxidation on MnO2-supported Pt13 clusters

Abstract

The interface formed by metal clusters supported on (reducible) transition metal oxides (TMOs) is usually responsible for the excellent activity of the redox reaction in the heterogeneously catalytic field. In this work, the catalytic combustion of CO was selected as a typical probe reaction to theoretically reveal the features of Pt13/β-MnO2 (1 1 0) catalyst, which possesses four active sites i.e., interface, β-MnO2 (1 1 0) facet, metallicity (Pt0) and partial oxidized Pt (Ptx+). All active sites were carefully investigated by the characteristics of CO oxidation. For Pt0 and Ptx+ sites, the adsorption energies of CO are larger than those of O2, which might block O2 active sites and cause CO poison. Meanwhile, CO oxidation by the dissociated O atom has the relatively high reaction energy barrier. Thus, Pt0 and Ptx+ are not good active sites for CO oxidation. For β-MnO2 (1 1 0) facet, O2 dissociation is not easy with a high barrier for vacancies healing. In contrast, the most favorable mechanism of CO oxidation is the catalytic cycle at the interface, with low reaction energy barriers in the entire pathway. We hope this comprehensive work can provide a meaningful reference towards the design of heterogeneous catalysts.