O doping hierarchical NiCoP/Ni2P hybrid with modulated electron density for efficient alkaline hydrogen evolution reaction

Herein, we design an O-incorporated hierarchical NiCoP/Ni2P hybrid electrodes (O-NiCoP/Ni2P) through a simple progressive phosphatization and dip-coating strategy to overcome the additional cost caused by heteroatom doping. The resulting O-NiCoP/Ni2P displays an ultra-low overpotential of 58 mV at 10 mA cm-2 and longterm stability over 24 h for efficient alkaline hydrogen evolution reaction (HER). Based on the density functional theory simulations, the O doping is beneficial to optimize the free energy of hydrogen/water absorption, which accelerates the HER process. Besides, the strong coupling of O-NiCoP/Ni2P has a positive effect on the electron transfer, thereby improving its catalytic performance. This work provides a potential pathway to the rational design of transition-metal phosphides based HER electrocatalysts and element-doping for energy conversion applications.