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

Hydrogen evolution reaction (HER) is a vital step in water electrolysis toward H₂ production. However, conventional nanocatalysts lack uniform size, composition, structure, and a homogeneous chemical coordination environment, causing the retrieval of an unambiguous structure–performance relationship to be extremely challenging. Owing to its ultra-small size, definitive composition, well-defined structure, and uniform chemical environment at the atomic level, atomically precise Au nanoclusters can serve as a model catalyst to improve understanding of the relationship between the structure and its catalytic properties. First, this review describes the fundamental mechanism and significance of HER and highlights the unique advantages of employing Au nanoclusters as a model catalyst. Then, the recent progress involving the promotion and catalysis of HER by Au and Au-alloy nanoclusters is discussed, with a focus on elaborating the structure–performance relationship. The key factors affecting the catalytic performance, including but not limited to the electronic interaction, interfacial effect, size effect, charge state, ligand effect, metal core composition, single-atom doping, and geometric configuration effect, are analyzed with explicit examples. Finally, the current critical challenges involved in this process and future perspectives are discussed. We hope that this review can shed light on the design of efficient and stable coinage metal-nanocluster-based catalysts toward electrochemical H₂ production and beyond.