From fundamentals and theories to heterostructured electrocatalyst design: An in-depth understanding of alkaline hydrogen evolution reaction

Anion exchange membrane water electrolyzers (AEMWEs) feature compelling advantages over the current benchmarking proton exchange membrane water electrolyzers (PEMWEs). However, the sluggish hydrogen evolution kinetics in alkaline media and its elusive mechanism, greatly impede the practical deployment of AEMWEs. A clear understanding of alkaline hydrogen evolution reaction (HER) mechanism is a prerequisite to design advanced electrocatalysts for AEMWEs. High-performance alkaline HER electrocatalysts have been extensively reported, but most of these development practices are at the trial-and-error stage. Herein, we contribute an in-depth review of alkaline HER by integrating mechanistic and theoretical understanding of alkaline hydrogen evolution into a series of classical catalyst design cases, with special focus on the critical role of interface chemistry in tailoring the intrinsic activity of platinum group metal-based heterostructured electrocatalysts, aiming to provide a solid guidance for rational design of advanced alkaline HER electrocatalysts for AEMWEs.