Hydrogen Evolution Reaction: Mechanistic Insights and Emerging Design Strategies for Efficient Catalysis

ABSTRACT The hydrogen evolution reaction (HER) plays a pivotal role in electrochemical water splitting and clean hydrogen production but is often hindered by sluggish reaction kinetics, particularly in alkaline media. While extensive efforts have been made to design high‐performance electrocatalysts, most studies emphasize material classifications over fundamental mechanistic understanding. In this review, we adopt a step‐specific perspective, systematically analysing how advanced catalyst architectures address the distinct kinetic barriers of the Volmer, Heyrovsky, and Tafel steps involved in the overall process. In addition, recent advances in electrode–interface engineering aimed at controlling bubble nucleation, growth, and detachment interfacial phenomena and its influence in mass transport and thereby HER kinetics has also been explored. We highlight key developments in water dissociation promoters, electronic structure tuning, interfacial engineering, and defect‐rich nanostructures that enhance each elementary step. Particular emphasis is placed on bifunctional and dual‐site catalysts that achieve multi‐step acceleration through cooperative mechanisms. By correlating catalytic performance with individual reaction steps, this review provides a mechanistic framework that transcends traditional material taxonomies, offering design principles for next‐generation HER catalysts. These insights aim to guide the development of scalable, efficient hydrogen production technologies for future clean energy systems.