Recent development of metal single atoms-confined 0D-3D carbon supports as bifunctional electrocatalysts for water splitting applications.

The design of cost-effective, highly active catalysts is urgently needed in electrocatalysis. Single-atom catalysts (SACs) are a novel catalyst family that has attracted considerable attention for their unique properties and catalytic performance, arising from rich electroactive sites, tailored structural design, and modulated electronic properties. The development of well-distributed SACs not only provides a good opportunity to observe and understand the reaction mechanism at the atomic scale but also significantly enhances catalytic efficiency. Thus, the design of SACs on efficient 0D-3D carbon supporting materials is a promising approach to enhance active sites and maintain stability during electrocatalytic processes. Herein, we provide a critical review of recent advances in state-of-the-art SACs. The correlation among their structure, physicochemical properties, and catalytic performance is discussed to elucidate their enhanced performance. Furthermore, emerging electrochemical applications of SACs for hydrogen and oxygen evolution reactions will be highlighted. Lastly, several challenges and prospects for the development of SACs are briefly discussed.