Recent Advances in Transition Metal‐Based Catalysts and Strategies for Promoting Alkaline Water Electrolysis

Hydrogen has been regarded as one of the most promising energy carriers, which enables the reduction of reliance on conventional fossil fuels. However, the sluggish kinetics of the electrochemical water electrolysis under alkaline conditions has proposed great challenges for the production of hydrogen on a large scale. In particular, both the thermodynamic energy demand, reflected by enthalpy changes, and the kinetic barriers of water dissociation strongly influence the overall efficiency of the alkaline hydrogen evolution reaction (HER). On the one hand, the underlying mechanism of alkaline HER is still under debate. On the other hand, the catalysts that display exceptional electrocatalytic activity in acid media may experience incompatibility with the oxygen evolution reaction catalysts that usually determine the overall water electrolysis. Herein, we first introduced the state of the art of catalysts developed in recent years. Then, we summarized and highlighted how the electrocatalytic performance of transition metal catalysts could be improved by composition and structure engineering strategies such as alloying, heteroatom doping, constructing heterostructure/interface, regulating the microenvironment of single-atom sites, and supporting effects. Finally, a summary and outlook were made. This review may provide insightful information for the future development of alkaline catalysts.