In recent years, various electro- and photocatalysts with exceptional performance in renewable energy conversion have emerged as promising candidates for addressing escalating energy demands and environmental challenges. However, a comprehensive understanding of their catalytic mechanisms remains limited due to the complex compositions and structures of conventional catalysts. Atomically precise metal nanoclusters (MNCs), such as gold, silver, and their alloys, have demonstrated significant advances in catalysis owing to their well-defined and tunable geometric and electronic structures, high atom utilization efficiency, and peripheral capping ligands. Unlike their bulk counterparts, ligand-protected MNCs possess precise molecular formulas and atomic structures, enabling rational design strategies to optimize catalytic activity and selectivity for specific reactions while providing detailed insights into the relationship between catalytic performance and structure/composition at the atomic level. In this review, the synthetic methods for MNCs are systematically explicated, followed by a detailed discussion of the electrochemical gap associated with their electronic structures. Subsequently, recent advances in the applications of MNCs in important catalytic reactions are comprehensively summarized, with particular emphasis on their electrocatalytic performance in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), electrochemical CO 2 reduction reaction (CO 2 RR), and electrochemical nitrogen fixation (ENF), as well as their photocatalytic performance in pollutant degradation, water splitting, CO 2 reduction, N 2 fixation, singlet oxygen generation, and oxidation reactions. We discuss the key factors influencing electro- and photocatalytic performance, including size, shape, composition, charge, ligands, and support materials, while exploring the underlying electro- and photo-catalytic mechanisms. Finally, the major challenges and future perspectives in this rapidly evolving field are highlighted.
He et al. (Fri,) studied this question.