Minireview of the Electrocatalytic Local Environment in Alkaline Hydrogen Evolution

The electrocatalytic hydrogen evolution reaction (HER) in an alkaline environment is one of the most important energy conversion processes as a result of its fundamental value in studying a variety of electrocatalytic cathode reactions. However, the reaction mechanism of alkaline HER is still unclear, which challenges the improvement of the slow HER kinetics and the design of an efficient catalyst in a non-acidic environment. With the aid of the advanced operando characterizations and increasing simulation techniques, recent studies have discovered that the origin of the sluggish kinetics in alkaline HER originates from its special electrocatalytic local environment. To address this issue, here, we present a thorough review on the current knowledge of the reaction mechanism of alkaline HER, emphasizing the latest understanding on how the electrocatalytic local environment determines the reaction kinetics. Specially, we briefly discuss the methodology for studying and altering the electrocatalytic interface via in situ approaches. We aim to provide new strategies and guidelines for the study and engineering of the electrocatalytic local environment in alkaline HER.