Constructing porous boron doped nickel phosphide (Ni2P) rod arrays with optimized electron coordination for alkaline hydrogen evolution

Transition metal-based phosphides (TMPs) show great potential for hydrogen evolution reaction (HER). The fine regulation of the electronic structure of metal-rich phosphides is an effective and challenging strategy for better activity. Herein, a simple and effective molten salt treatment is designed to synthesize porous boron doped Ni 2 P rod nanoarrays (M-B-Ni 2 P) for alkaline HER. The molten salt treatment facilitates the formation of unique porous Ni 2 P rod nanoarrays with homogeneous boron doping. The synthesized porous M-B-Ni 2 P exhibit excellent catalytic performance in alkaline media, requiring only an overpotential of 217 mV to drive 100 mA cm -2 , which is 79 mV lower than binary nickel phosphide (M-Ni 2 P). The boron doping not only optimizes the porous geometry to increase the number of active sites, but also regulates the electronic coordination to promote the dissociation of water and the adsorption and desorption of hydrogen atoms. In addition, the self-supported monolithic M-B-Ni 2 P electrode can operate at a larger current density of 100 mA cm -2 for at least 100 h. This study on realizing boron doping based on molten salt treatment provides a new strategy for constructing transition metal-based phosphides as electrocatalysts. • The molten salt treatment facilitates the formation of unique porous Ni 2 P rod nanoarrays with homogeneous boron doping. • The boron doping optimizes geometry to increase active sites, and regulates the electronic coordination to improve reaction kinetics. • The porous M-B-Ni 2 P exhibit excellent catalytic HER performance in alkaline media. • The self-supported 3D electrode ensures the stability of the catalyst.