3D carbon quantum dots/graphene aerogel as a metal-free catalyst for enhanced photosensitization efficiency

Carbon quantum dots (CQDs) have recently emerged as the light-harvesting antennas for photocatalytic applications due to their outstanding optical absorption, nontoxicity, unsophisticated synthesis and scalable production. However, the poor photocatalytic efficiency and difficult recovery of CQDs restrict their large-scale practical applications in aqueous photocatalytic reactions. Here we report a facile synthesis of metal-free three-dimensional (3D) construction of CQDs spatially distributed into the frameworks of graphene aerogel (CQDs/GA) with enhanced photocatalytic performance compared to the bare CQDs. The photoelectrochemical characterizations demonstrate that 3D graphene aerogel (GA) with interconnected networks exhibits efficient spatial separation and transportation of photoexcited charge carriers, thereby leading to the improved photocatalytic activity of the CQDs/GA composites. In addition, such 3D bulk aerogel displays easy separability from liquid-phase reaction system and regenerability via simple replenishment of CQDs, which ensures the sustainable photoactivity of the CQDs/GA composites. This approach for preparing 3D CQDs/GA composites is expected to open a new vista for constructing metal-free and regenerable photocatalysts with enhanced photosensitization efficiency of CQDs.