Tuning the structure of bifunctional Pt/SmMn2O5 interfaces for promoted low-temperature CO oxidation activity

Abstract

The interfacial structure of metal–oxide composite catalysts plays a vital role in heterogeneous catalysis, which is crucial to the adsorption and activation of reactants. Herein, the interfacial effects of bare and Fe/Co/Ni doped SmMn₂O₅ mullite oxide supported Pt clusters on CO oxidation have been investigated by first-principles based microkinetics analysis. A robust formation of Pt/Mn₂ trimer structures is demonstrated at the bifunctional interfaces irrespective of the Pt_n cluster's size, which can provide spatially separated sites for CO adsorption and O₂ dissociation. The binding strength of CO at the interfacial Pt sites is in the optimal range due to the charge transfer from Pt clusters to oxide, while the strong polarization of Mn₂ dimers induced by Pt clusters with stable three-dimensional morphologies can lower the energy barrier of O₂ dissociation. Based on the microkinetics analysis, the O₂ dissociation is the rate-determining step in the full CO oxidation cycle, and the introduction of Mn–Fe hetero-dimers at the interface is predicted to further enhance the low temperature CO oxidation activity of Pt/SmMn₂O₅ catalysts.