Synthesis of Pure-Phase Ni2P Nanocatalysts via Phosphorus Ligand Selection for Efficient Hydrogen Evolution Reaction

Developing facile and low-cost synthetic methods of high-active platinum group metal-free electrocatalysts is essential for green hydrogen production primarily based on water electrolysis. We adopted a facile solution-based synthetic approach to prepare nickel phosphide nanoparticles (NP) and systematically studied the role of phosphorus ligands in the synthesis. Pure-phase Ni2P NPs were obtained by selecting the proper phosphorus ligands, which tuned the structures of the product. The Ni2P nanowire, prepared using triphenyl phosphite, exhibited the best activity and stability in acidic, neutral, and alkaline media for hydrogen evolution reaction (HER), indicating the advantages of the nanowire structure to the performance. In the acidic medium, it only required overpotential values of 100 and 167 mV to achieve the HER current densities of 10 and 100 mA cm(-2), respectively. Furthermore, the overpotential increased only by 26 mV during the 50-hour stability test, indicating potential for device application. It was also demonstrated that the on-site generation of insoluble nickel salts (e. g., hydroxides, phosphates, etc.) on the surface resulted in lower activity and stability in neutral and alkaline media than in acid.