Electronic structure regulations of single-atom site catalysts and their effects on the electrocatalytic performances

In recent years, single-atom site catalysts (SACs) have achieved great advancements in heterogeneous and electrochemical catalysis due to the merits of maximal atom utilization, unique electronic and geometric structures, low costs, and high catalytic performances. The electronic structures of the isolated metal centers can greatly influence the adsorption energies of reactants and intermediates, thus determining the catalytic activities of SACs. Especially, the electronic structure regulation of the metal sites has been advanced to the atomic level and proven a powerful strategy to enhance their electrocatalytic performances, which provides great opportunities for the further development of SACs. Based on the reported synthesis and structural modulation methods, in this review, the experimental and computational advances in the electronic structure regulation strategies for SACs, including coordination adjustment, electronic metal-support interaction, oxidation state modulation, and strain engineering, will be summarized. Then, the effects of electronic structures on the adsorption behaviors and, thus, the electrocatalytic activities of water splitting and O2/CO2 reduction reactions will be emphatically exemplified and discussed. In the end, a brief conclusion of this paper and the existing challenges and future opportunities in this research direction will be proposed. This review aims to highlight the understanding of electronic structure in association to the electrocatalytic activity for SACs and provide guidance for their further development in electrochemical applications.