Stabilization of Single Metal Atoms on Graphitic Carbon Nitride: Synthetic Strategies and Emerging Applications

Emerging as a new frontier in catalysis science, single-atom catalysts (SACs) have sparked broad attention owing to their maximum atom utilization efficiency, well-defined active sites, and unique structures and properties. The prerequisite for the scientific research and practical application of SACs is to stabilize and maintain the highly reactive isolated metal atoms on suitable supports. Graphitic carbon nitride (g-C₃N₄), with characteristic 2D architecture, abundant unsaturated nitrogen coordination sites, and periodic structural cavities, serves as an exceptional substrate for stabilizing isolated SACs, while the inherent semiconductor nature further enables visible-light-responsive photocatalytic activity for solar energy conversion and environmental remediation. Importantly, an intensive investigation has pushed the study of SACs@g-C₃N₄ far beyond what people can imagine in the beginning, but less well summarized. Herein, a panorama review of recent advances in SACs@g-C₃N₄ catalysts, including i) advanced synthetic strategies for SACs@g-C₃N₄ with special emphasis on the stabilization of isolated metal atoms against migration and aggregation during the synthesis processes, and ii) appealing achievements of SACs@g-C₃N₄ in a variety of emerging applications, including electrocatalysis, photocatalysis, and organic chemical transformations. Finally, current challenges are highlighted and an outlook on the prospects for future development of this fascinating research hotspot is presented based on pioneering studies.