Surface modification engineering on three-dimensional self-supported NiCoP to construct NiCoOx/NiCoP for highly efficient alkaline hydrogen evolution reaction

Abstract The development of highly active and low-cost metal electrocatalysts for hydrogen evolution reaction (HER) is crucial for application of water electrolysis. In this work, a novel and facile strategy to fabricate self-supported NiCoOx/NiCoP film was proposed via a simple surface modification engineering process with in situ electrochemical oxidation directly applied to NiCoP porous film. The electrocatalytic performance of the obtained NiCoOx/NiCoP is significantly optimized after surface modification engineering. NiCoOx/NiCoP film exhibits excellent catalytic activity toward HER, which only requires an overpotential of 35 and 104 mV to reach the current density of 10 and 100 mA cm−2 in alkaline solution, respectively, while NiCoP film requires an overpotential of 66 and 140 mV at the same current density. Meanwhile, the self-supported NiCoOx/NiCoP film shows a low Tafel slope of 56 mV/dec and superior long-term stability. The HER activities of NiCoOx/NiCoP films obtained by in situ anodic oxidation with different time duration reveal that an appropriate anodic oxidation time duration is important and beneficial for achieving improved HER activity without changing the microstructure. This simple method provides a promising avenue for designing and constructing high-performance HER electrocatalysts with lower cost.