Highly efficient and stable electrocatalyst for hydrogen evolution by molybdenum doped Ni-Co phosphide nanoneedles at high current density

Abstract

There is an increasingly urgent need to develop cost-effective electrocatalysts with high catalytic activity and stability as alternatives to the traditional Pt/C in catalysts in water electrolysis. In this study, microspheres composed of Mo-doped NiCoP nanoneedles supported on nickel foam were prepared to address this challenge. The results show that the nanoneedles provide sufficient active sites for efficient electron transfer; the small-sized effect and the micro-scale roughness enhance the entry of reactants and the release of hydrogen bubbles; the Mo doping effectively improves the electrocatalytic performance of NiCoP in alkaline media. The catalyst exhibits low hydrogen evolution overpotentials of 38.5 and 217.5 mV at a current density of 10 mA·cm−2 and high current density of 500 mA·cm−2, respectively, and only 1.978 V is required to achieve a current density of 1000 mA·cm−2 for overall water splitting. Density functional theory (DFT) calculations show that the improved hydrogen evolution performance can be explained as a result of the Mo doping, which serves to reduce the interaction between NiCoP and intermediates, optimize the Gibbs free energy of hydrogen adsorption (ΔG∗H), and accelerate the desorption rate of *OH. This study provides a promising solution to the ongoing challenge of designing efficient electrocatalysts for high-current-density hydrogen production.