Mo, Co co-doped NiS bulks supported on Ni foam as an efficient electrocatalyst for overall water splitting in alkaline media

Abstract

In this study, a composite of Mo, Co co-doped NiS bulks grown on an Ni foam (Mo,Co-NiS/NF) was synthesized as a bi-functional electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using a simple method. The existence of ZIF-67 and Mo ensure the even distribution of Co and Mo elements and the formation of N doped carbon layer in Mo, Co-NiS/NF. Mo, Co co-doping and NF support greatly improved the electrocatalytic performance of NiS bulks, because metal element doping could improve the intrinsic activity and electrical conductivity. Moreover, the Ni foam could act as a substrate to avoid aggregation and provide nickel source to form the bimetallic sulfide. The product Mo,Co-NiS/NF-400 showed outstanding electrochemical properties, with ultralow overpotential (92 mV vs. RHE) for HER and ultralow overpotential (117.2 mV vs. RHE) for OER to achieve 10 mA cm⁻², as well as the ultralow cell voltage (1.36 V) to achieve 20 mA cm⁻² for overall water splitting. This study provides an available method to promote the electrocatalytic activity of the traditional monometallic sulfides for overall water splitting.