Monodisperse PdCu@PtCu Core@Shell nanocrystal and their high activity and durability for oxygen reduction reaction

Core@shell nanocrystals (NCs) have been widely explored for oxygen reduction reaction (ORR). In this work, monodisperse PdCu@PtCu NCs with various shell thicknesses and compositions have been synthesized through a two-step protocol. As-synthesized PdCu@PtCu core@shell catalysts show enhanced specific activities (SAs) and mass activities (MAs) towards ORR. When PdCu/PtxCuy (core/shell) atomic ratio and Pt/Cu (x/y) ratio both reach 1/1, the core@shell catalyst exhibits the highest SA and MA (normalized with total mass of Pt and Pd). It is also found that the core@shell catalysts show drastically enhanced stability compared with pure PtCu alloy catalyst. It is proposed that both the activity and stability enhancements can be ascribed to the electronic interaction or charge transfer between Pd atoms (in core) and the shell elements. This work demonstrates a new family of core@shell catalysts that can be potentially used as cathode electro-catalysts in fuel cells.