▎ 摘　　要

Cobalt phosphides based materials are considered as promising electrocatalysts for the hydrogen evolution reaction (HER). The catalytic performance can be further enhanced by improving the intrinsic catalytic activity, exposing more active sites and coupling with conductive support. Herein, a novel electrocatalyst based on nitrogen doped reduced graphene oxides decorates with uniformly distributed CoPx nanoparticles with a suitable P/Co ratio (x = 1.7) via a facile and mild condition. The optimized composite (CoPx/N-rGO) exhibits superior electrocatalytic HER activities with a low overpotential of 104 mV (at 10 mA cm(-2)), a small Tafel slope of 65 mV dec(-1), and long-term stability in the alkaline media, comparable to the performance of other HER electrocatalysts. The remarkable HER performance can be ascribed to the good electrical conductivity of rGO and extra active sites created by nitrogen doping. In addition, the ultrafine nanostructure (average particle size approximate to 4 nm) and well-dispersed CoPx nanoparticles also help expose more active sites for electrocatalytic reactions, largely hindering the agglomeration and exfoliation. This work provides a versatile route on the design of multifunctional composite materials for renewable energy research with low cost and high activity.