Vacancy Regulates the Electronic Structure and Microenvironment of Ni-Based Heterostructures to Promote Alkaline Hydrogen Evolution Reaction

The alkaline hydrogen evolution reaction performance of Ni-based catalysts is strongly affected by sluggish water dissociation, slow H* transport, and inappropriate H* adsorption. However, there is still a lack of efficient strategies to thoroughly solve the existing challenges, making their mass activity much lower than that of Pt catalysts. Herein, we discover that P vacancy engineering not only creates a local acid-like microenvironment to promote H* transport but also regulates the heterointerface electronic structure to optimize H* adsorption. In addition, constructing heterostructures combined with oxyphilic species and nickel phosphide favors breaking the H–OH bond, thus accelerating water dissociation. Noteworthy, the mass activity of optimized Ni2Pv-1.2-Ni(OH)2-5/NF (v stands for vacancy) reaches 0.85 A mgNi–1 at −0.114 V vs RHE, close to commercial Pt/C (0.91 A mgPt–1) for the first time. In addition, the anion exchange membrane electrolyzer assembled with Ni2Pv-1.2-Ni(OH)2-5/NF needs only 1.86 V to achieve 1.0 A cm–2 and could work stably for 500 h.