Altering the electronic structure and surface chemical environment of Pt{100} facets via synergizing with Ir species for enhanced oxygen-reduction activity and stability

Abstract

Shape-controlled metal-based nanomaterials provide a special platform to regulate the surface physicochemical properties for optimizing the electrocatalytic performance, due to their homogeneously arranged surface atomic structures. Accordingly, owing to the solely {100} facets-ended surfaces, highly uniform Pt nanocubes (NCs) are utilized in this study, to probe the effects of synergizing with Ir species (a very effective metal for various electrocatalysis) on the electrocatalytic performance for the oxygen reduction reaction (ORR). Electrochemical results present that carbon-supported Pt1Ir1 NCs with surface Ir–O species (Pt1Ir1–O NCs/C) have much enhanced electrocatalytic activity and electrochemical stability than both Pt NCs/C and commercial Pt/C. Physicochemical characterization and theoretical calculation analyses further elucidate the mechanism of the improved electrocatalytic performance: the strong electronic interaction between Pt and Ir, the lowered d-band center of the surface metal atoms, and especially the synergistic effect induced by the surface Ir–O species. This study not only develops a highly active and stable ORR electrocatalyst, but also demonstrates an effective and universal research paradigm to explore the surface engineering effects on the electrocatalytic performance, which can be further applied in other crystalline facets for other (electro)catalytic reactions.