Recent Progress on Non-Carbon-Supported Single-Atom Catalysts for Electrochemical Conversion of Green Energy.

Single-atom catalysts (SACs) are a popular area of research for clean energy conversion owing to their cost-effectiveness and excellent performance. The support plays a vital role in uniformly stabilizing and dispersing the single atoms. Although easily accessible carbon (C) is commonly selected as a support for SACs, its electrochemical properties, particularly stability, usually limits its application. Recently, non-C materials with flexible physicochemical properties and unique metal-support interactions have attracted increasing attention for loading isolated metal atoms, showing promise for promoting catalytic performance. Therefore, in this review, a comprehensive summary of current research developments in non-C-supported SACs for green energy conversion is provided. The review begins with a brief introduction of the four types of non-C-supported SACs based on the support used. Thereafter, a systemic summary of synthesis methods for non-C-supported SACs analyzing their advantages and disadvantages is provided. The interactions between single metal atoms and non-C supports are discussed, followed by their applications in green energy conversion. Then, the significance of adopting a variety of in situ/operando approaches is emphasized to gain insight into both the synthesis and reaction mechanisms, which have been successfully deployed for non-C-supported SACs. Finally, the remaining challenges and perspectives on designing promising non-C-supported SACs are discussed.