Strategies for design of electrocatalysts for hydrogen evolution under alkaline conditions

Electrocatalytic hydrogen evolution reaction (HER) in alkaline environments is one of the major energy conversion processes in water electrolysis technology. Very active and cost-effective catalysts are highly desirable for alkaline HER not only for its industrial value but also for its fundamental importance in studying all electrocatalytic reactions occurring on cathode electrodes. However, to date, the reaction mechanism of alkaline HER is still under debate, which makes the design of catalysts largely a trial-and-error process. To address this issue, here we present strategies for the design of alkaline HER catalysts based on the current knowledge of the reaction mechanism by emphasizing the connection between the atomic-level materials engineering and reaction fundamentals. Particularly, we focus on the improvement of the inherent electronic structure of the materials to achieve desired interactions between the catalysts and reactive intermediates. By showing several successful examples of both theoretical and experimental design strategies, we aim to provide direct guidelines toward the design of catalysts for HER under alkaline conditions.