Advances in graphene quantum dots-based photocatalysts for enhanced charge transfer in photocatalytic reactions

The development of efficient green energy technology is imperative in the face of energy crises and environmental concerns. Photocatalysis, which utilizes solar energy for processes such as carbon dioxide (CO₂) reduction, organic pollutants degradation, and hydrogen (H₂) production through water splitting, is a promising approach. The key to high-efficiency photocatalysis lies in the design of superior photocatalysts. Graphene quantum dots (GQDs) have sparked significant interest in photocatalysis due to their exceptional up conversion photoluminescence (UCPL), strong light-capturing capability, and unique photoinduced charge transfer properties. However, their standalone use is limited by stability and activity. By integrating GQDs into composite photocatalysts, the separation of photogenerated electron-hole pairs is enhanced, boosting photocatalytic performance. This review provides the first overview and summary of the preparation methods of GQDs in photocatalysts, encompassing top-down and bottom-up strategy. Subsequently, a pioneering detailed summary was made on the applications of GQDs-semiconductor composites (metal organic frameworks, CdS, and bismuth-based oxides, etc.) in photocatalytic reactions such as CO₂ reduction, organic pollutant degradation, and H₂ generation. Furthermore, the corresponding representative examples and mechanisms are also elaborated and discussed respectively. Finally, the challenges and prospects for GQDs-based photocatalysts in the field of photocatalysis are proposed. This review provides inspiration and guidance for the development of efficient GQDs-based photocatalysts.