Atomically precise Au nanoclusters for electrochemical hydrogen evolution catalysis: Progress and perspectives

Hydrogen evolution reaction (HER) is a vital step for water electrolysis toward H₂ production, but the conventional nanocatalysts lack uniform size, composition, structure, and chemical coordination environment hence making it extremely challenging to establish the unambiguous structure-performance relationship. Owing to the ultrasmall size, definitive composition, well-defined structure, and uniform chemical environment at the atomic level, atomically precise Au nanoclusters can serve as model catalysts to improve the knowledge gap between the structure and the catalytic properties. This review first explains the significance and fundamental mechanism of HER, and highlights the unique advantages of employing Au nanoclusters as model catalysts. Subsequently, the recent progress including Au nanoclusters promote HER, Au nanoclusters catalyze HER, and Au-alloy nanoclusters for HER is discussed, with focus on elaborating the structure-performance relationship. With some explicit examples, the key factors that affect the catalytic performance including but not limited to electronic interaction, interfacial effect, size effect, charge state, ligand effect, metal core composition, single atom doping, and geometric configuration effect are analyzed. Finally, the current critical challenges and future perspectives are discussed. We hope this review can shed light on designing efficient and stable coinage metal nanocluster-based catalyst toward electrochemical H₂ production and beyond.