Enhanced electrocatalytic performance of Ni-based phosphides via dual regulation of Co-introducing and graphene-support for hydrogen evolution

Abstract

Ni-based phosphides are a kind of promising electrocatalyst for the hydrogen evolution reaction (HER). However, the catalytic activity of phosphides still needs further improvement. Herein, with the incorporation of Co, highly dispersed spherical NiCoP supported on graphene nanosheets (NiCoP/GR) as HER catalyst was successfully prepared by the simple impregnation and phosphorization method. The highly-dispersed morphology and the synergetic interaction between NiCo bimetal endow the as-prepared NiCoP/GR with high catalytic performance for HER. When the current density is 10 mA cm−2 in 0.5 M H2SO4, the as-prepared NiCoP/GR exhibited a low overpotential of 195 mV, and the Tafel slope was only 66.4 mV dec−1. Furthermore, the density functional theory (DFT) calculations reveal that the low activation barrier of NiCoP/GR can be ascribed to the adjustment of electronic structure. As a result, the HER catalytic performance of NiCoP/GR is significantly enhanced by electronic structure adjustment. This work provides a new approach for introducing multiple metal elements and graphene support material with unique properties to boost the catalytic performance of transition metal phosphide catalysts.