With the further exploitation of renewable energy sources, electrochemical hydrogen evolution reaction (HER) is considered a key technology to solve environmental problems and achieve global carbon neutrality. Currently, alkaline water electrolyzers (AWEs) have been revitalized as a traditional electrolytic water production industry, yet they face great challenges in achieving new technological breakthroughs due to the catalytic properties of electrode materials. In alkaline media, besides the slow kinetics of oxygen evolution reaction, the sluggish HER needing water dissociation and the mass transfer problems at high current densities are among the major factors limiting the development of alkaline water electrolysis for industrial applications. Therefore, it is of great importance to design HER electrocatalysts with high activity and stability at high current densities (>500 mA cm−2) for industrial applications at the “Research and Development level” (R&D level). Herein, a brief overview of the development of AWEs at the industrial scale is presented, and some mainstream recognized catalysis mechanisms for HER in alkaline electrolytes are summarized. Based on the requirements of industrial application and theoretical guidance, the activation strategies of HER electrocatalysts are also summarized. This review will propose new insights into the future development of alkaline water electrolysis.

Hydrogen generated by proton exchange membrane (PEM) electrolyzer holds a promising potential to complement the traditional energy structure and achieve the global target of carbon neutrality for its efficient, clean, and sustainable nature. The acidic oxygen evolution reaction (OER), owing to its sluggish kinetic process, remains a bottleneck that dominates the efficiency of overall water splitting. Over the past few decades, tremendous efforts have been devoted to exploring OER activity, whereas most show unsatisfying stability to meet the demand for industrial application of PEM electrolyzer. In this review, systematic considerations of the origin and strategies based on OER stability challenges are focused on. Intrinsic deactivation of the material and the extrinsic balance of plant‐induced destabilization are summarized. Accordingly, rational strategies for catalyst design including doping and leaching, support effect, coordination effect, strain engineering, phase and facet engineering are discussed for their contribution to the promoted OER stability. Moreover, advanced in situ/operando characterization techniques are put forward to shed light on the OER pathways as well as the structural evolution of the OER catalyst, giving insight into the deactivation mechanisms. Finally, outlooks toward future efforts on the development of long‐term and practical electrocatalysts for the PEM electrolyzer are provided.

A controlled amount of nitrogen is introduced into the NiMo alloy to obtain a bimetallic nitride with improved activity and stability, resulting in a stability of over 50 h at a current density of 1.0 A cm−2 under 2.17 V in an anion membrane flow cell.