Advances in single atom alloy: synthesis, electronic regulation and application in energy-related electrocatalysis

Single-atom alloy catalysts (SAAs), which consist of catalytically active metal atoms atomically dispersed within inert metal matrices, have recently attracted considerable attention. SAAs combine the merit of maximized atomic utilization from single-atom catalysts (SACs) with the feature of intermetallic electronic synergetic modulation from alloy catalysts. This enables the synergetic catalysis of multiple active sites, achieving highly active and selective catalysis. Hence, in this review, we summarize recent progress of SAAs from the perspective of synthetic methods, unique electronic properties, and their applications in a series of energy-related electrocatalytic reactions. First, the major approaches, including impregnation, sequential reduction, galvanic replacement, atomic layer deposition, and electrochemical reconstruction, for the fabrication of SAAs are overviewed. Second, the unique electronic properties between single-atom sites and metal supports in SAAs, including free-atom-like d-state, charge transfer, and energy band structure, are further elaborated. Then, the applications of SAAs in various energy-related electrocatalytic reactions are discussed to elucidate the structure-performance relationships and understand the reaction mechanisms. Finally, a conclusion of this review and insights into the challenges and prospects pertaining to this field are also highlighted.