Theoretical Study of the Role of a Metal–Cation Ensemble at the Oxide–Metal Boundary on CO Oxidation

Abstract

Identification of the active sites in heterogeneous catalysis is important for a mechanistic understanding of the structure–reactivity relationship and rationale of the design of new catalysts, but remains challenging. Among others, the boundaries at metal nanoparticles and supported oxides were found to be important and attributed to the active sites in various catalytic reactions. To reveal the nature of the active sites at the boundaries, the catalytic role of the inverse 3d transition-metal oxide nanoislands on Pt(111) for low-temperature CO oxidation was studied by density functional theory calculations. A characteristic Pt–cation ensemble at the oxide/metal boundaries as the active sites is identified. In Pt–cation ensembles, coordinate-unsaturated (CUS) cations exposed at the edges of oxide nanoislands are highly active for O2 adsorption and dissociation, and less-reactive Pt binds modestly with dissociated O responsible for the facile CO oxidation. Inverse VIIIB-oxide/Pt boundaries exhibit high ac...