Hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) have aroused great interest, but the high price of platinum group metals (PGMs) limits their development.The electronic reconstruction at the interface of a heterostructure is a promising strategy to enhance their catalytic performance. Here, MoO 2 /Ni heterostructure was synthesized to provide effective HER in an alkaline electrolyte and exhibit excellent HOR performance. Theoretical and experimental analyses prove that the electron density around the Ni atom is reduced. The electron density modulation optimizes the hydrogen adsorption and hydroxide adsorption free energy, which can effectively improve the activity of both HER and HOR. Accordingly, the prepared MoO 2 /Ni@NF catalyst reveals robust HER activity (η 10 = 50.48 mV) and HOR activity (j 0 = ∼1.21 mA cm −2 ). This work demonstrates an effective method to design heterostructure interfaces and tailor the surface electronic structure to improve HER/HOR performance.

Transition metal nitrides and elemental doping are effective methods to enhance the catalytic activity of hydrogen evolution reaction (HER) at a high current density. Herein, Ni-W2N@NF was synthesized to exhibit excellent HER performance in an alkaline environment. Not only theoretical but also experimental analyses prove that Ni enters the W2N lattice in the form of substitutional doping. Ni-doped W2N optimizes the free energy of hydrogen adsorption and hydroxide adsorption. Thus, the HER kinetics are accelerated. Therefore, the synthesized Ni-W2N@NF achieved an industrial high current density of 2000 mA cm–2 in 1 M KOH with a small overpotential of 317 mV. The HER activity of Ni-W2N@NF is superior to those of most reports. What is more, the obtained catalyst achieves a current density of 1500 mA cm–2 in an alkaline seawater solution with an overpotential of only 345 mV and exhibits excellent cycling stability. This work will offer a feasible idea for a designing platinum group metals free metal as an effective catalyst for HER reaction under an industrial large current in an alkaline solution.