Electronic Structure Regulated Carbon-Based Single-Atom Catalysts for Highly Efficient and Stable Electrocatalysis

Single-atom-catalysts (SACs) with atomically dispersed sites on carbon substrates have attained great advancements in electrocatalysis regarding maximum atomic utilization, unique chemical properties, and high catalytic performance. Precisely regulating the electronic structure of single-atom sites offers a rational strategy to optimize reaction processes associated with the activation of reactive intermediates with enhanced electrocatalytic activities of SACs. Although several approaches are proposed in terms of charge transfer, band structure, orbital occupancy, and the spin state, the principles for how electronic structure controls the intrinsic electrocatalytic activity of SACs have not been sufficiently investigated. Herein, strategies for regulating the electronic structure of carbon-based SACs are first summarized, including nonmetal heteroatom doping, coordination number regulating, defect engineering, strain designing, and dual-metal-sites scheming. Second, the impacts of electronic structure on the activation behaviors of reactive intermediates and the electrocatalytic activities of water splitting, oxygen reduction reaction, and CO₂/N₂ electroreduction reactions are thoroughly discussed. The electronic structure-performance relationships are meticulously understood by combining key characterization techniques with density functional theory (DFT) calculations. Finally, a conclusion of this paper and insights into the challenges and future prospects in this field are proposed. This review highlights the understanding of electronic structure-correlated electrocatalytic activity for SACs and guides their progress in electrochemical applications.