Regulating the surface Pt coordination environment in the PtN overlayers on PtCuN hollow nanospheres for efficient oxygen reduction reaction

Abstract

Engineering the surface Pt coordination environment is a promising strategy for promoting the kinetically sluggish oxygen reduction reaction (ORR) on Pt-based catalysts. In this study, we achieve the compressive strain effect and electronic effect by Cu and N co-doping to synthesize the PtCuN hollow nanospheres with PtN overlayers (PtCuN@PtN HNSs) using a facile solvothermal synthesis. Electrochemical investigations show that the constructed disordered Pt–N coordination structures effectively facilitate the ORR and stabilize Pt atoms in the compressed lattice, whereas an excessive N-doping can lead to the formation of a structurally unstable Pt nitride phase. Theoretical analyses confirm that the oxygen reduction kinetics on the compressed PtN overlayers are regulated by a synergistic effect resulting from N-doping and lattice compression, circumventing the traditional linear scaling relationships (LSR). The optimized PtCuN@PtN HNSs, with the composition of PtCu0.29N1.1, demonstrate an area-specific activity of 1.98 mA cm–2 and a mass-specific activity of 1.81 A mgPt–1.