Synergy of facet control and surface metalloid modification on hierarchical Pt–Ni nanoroses toward high electrocatalytic activity

Abstract

Driven by the need of high catalytic performance and low cost Pt-based catalysts for methanol oxidation (MOR) and oxygen reduction (ORR) reactions, we developed a highly active nitrogen species-decorated Pt–Ni–N catalyst with tunable architectures and facets toward high catalytic activity. The synthetic procedure was conducted by Ni²⁺-assisted morphology and facet transformation from nanoflowers (NFs) (111) to nanoparticles (NPs) (220) and simultaneous optimization of both hierarchical structure and active surface sites. It is found that the adsorption of nitrogen species plays critical roles in determining both facet control of the Pt–Ni–N hierarchical structure and energetic activation of the catalytic reaction. Decoration of surface nitrogen species can effectually improve the relative content and electronic density of Pt⁰, leading to formation of a hierarchical structure and significantly improved catalytic activity toward both MOR and ORR compared with Pt–Ni and Pt–N, as well as the commercial Pt/C catalysts, indicating a new strategy to obtain highly efficient catalysts. Moreover, the results demonstrate that the catalytic enhancement is mainly due to the synergistic electronic effects among Pt, Ni, and N species.