Heteroepitaxial Interface of Pt//CeO2 Nanoparticles for Enhanced Catalysis in Oxygen Reduction Reaction (ORR)

Abstract

Metal-oxide nanocomposites (MONs) have garnered significant interest in catalysis due to their excellent performance in various chemical reactions. A key focus of research on MONs is the heteroepitaxial metal-oxide interface, which has been known to serve as a highly active catalytic center. In this report, we demonstrate that nanometer-sized MONs with heteroepitaxial interfaces can be materialized to exhibit enhanced catalytic performance owing to their strong interfacial effects. Specifically, a MON material composed of platinum (Pt) and cerium dioxide (CeO₂), denoted as Pt//CeO₂, can be obtained by exposing graphene-supported precursor Pt₅Ce alloy nanocrystals (Pt₅Ce/graphene), which are synthesized by the pyrolytic dissociation of chloroplatinic acid (H₂PtCl₆) and cerium trichloride (CeCl₃) in a hydrogen-containing atmosphere, to a gas mixture of carbon monoxide (CO) and oxygen (O₂) at elevated temperatures. Transmission electron microscopy (TEM) observations revealed a sharp heteroepitaxial interface between Pt(110) and CeO₂(110) planes within the Pt//CeO₂ material. This nanometer-sized heteroepitaxial interface showed a superior catalytic activity of Pt//CeO₂ compared to carbon-supported Pt and large-grained Pt//CeO₂ bulk catalysts for the oxygen reduction reaction (ORR) in basic media.