Emerging of carbon quantum dots-based powder materials for photocatalytic environmental remediation and chemical production

The climate crisis and global pollution urgently require cheap and sustainable methods to produce materials and clean ecosystems, such as photocatalysis that uses solar energy. Nonetheless, actual photocatalysts are limited by poor light absorption, low redox ability, high cost, and low efficiency. Here, we review the photocatalysis using carbon quantum dot (CQDs)-based nanomaterials, focusing on their synthesis, co-catalysts, single photocatalysts, and heterostructures through coordination of inorganic and organic semiconductors. They have low preparation cost, ultra-low ecological toxicity, favorable dispersibility, unique optical properties, and photoinduced charge transfer properties. Discovered in 2004, they have been applied in photocatalytic degradation of various organic pollutants, carbon dioxide reduction, hydrogen evolution, photocatalytic sterilization, organic synthesis, and hydrogen peroxide production. We compare the top-down and bottom-up preparation strategies for CQDs, presenting their recent applications in wastewater treatment, sterilization, degradation of gaseous pollutants, and the production of valuable chemicals. Lastly, with the emergence of defective CQDs, these materials appear promising for photocatalytic remediation technologies and the production of useful chemicals.