Vanadium Substitution Steering Reaction Kinetics Acceleration for NiN Nanosheets Endows Exceptionally Energy-Saving Hydrogen Evolution Coupled with Hydrazine Oxidation

Designing highly active transition-metal-based electrocatalysts for energy-saving electrochemical hydrogen evolution coupled with hydrazine oxidation possesses more economic prospects. However, the lack of bifunctional electrocatalysts and the absence of intrinsic structure-property relationship research consisting of adsorption configurations and dehydrogenation behavior of NH molecules still hinder the development. Now, a V-doped NiN nanosheet self-supported on Ni foam (V-NiN NS) is reported, which presents excellent bifunctional electrocatalytic performance toward both hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER). The resultant V-NiN NS achieves an ultralow working potential of 2 mV and a small overpotential of 70 mV at 10 mA cm in alkaline solution for HzOR and HER, respectively. Density functional theory calculations reveal that the vanadium substitution could effectively modulate the electronic structure of NiN, therefore facilitating the adsorption/desorption behavior of H* for HER, as well as boosting the dehydrogenation kinetics for HzOR.