Engineering Metal Nanoclusters at the Atomic Level for Effective Electrocatalysis

ABSTRACT With the advances of nanochemistry in the past several decades, a diverse set of nanomaterials has been developed as electrocatalysts with enhanced activity, selectivity, and durability for electrocatalytic reactions. However, it has remained as a long challenge to systematically understand the mechanism of electrocatalytic reactions, which involves multiple protons‐coupled electron transfer processes and varied products at the atomic level, intrinsically because of the complexity and polydispersity of the traditional nanomaterials. By sharp contrast, ligand‐protected metal nanoclusters (NCs) possess atomically precise structures and abundant active sites, facilitating their applications as effective model electrocatalysts for revealing the mechanism of electrocatalytic reactions. This review summarizes recent progress in atom‐level engineering of metal NCs as model catalysts for electrocatalytic reactions. Specifically, we first discuss the effects of metal composition engineering, including doping and size effects, on the electrocatalytic performance of metal NCs. Then similar electrocatalytic discussion extends to ligand effects of metal NCs, where ligand type and coverage engineering are deciphered. Moreover, we discuss how the overall charge and morphology of NCs modify their electrocatalytic performance. The fundamental and methodological insights summarized in this review should serve as useful references guiding the future development of effective metal electrocatalysts in diverse sectors of industry.