Carbon Quantum Dot-Based Hybrid Photocatalysts: A Perspective on Water Purification

Current environmental issues urge the creation of multifunctional photocatalysts with tailored properties for water purification processes. Luminescent carbon quantum dots (CQDs) have drawn a great deal of interest in heterogeneous photocatalysis because of their good water dispersibility, exceptional electron transport, and effective light-harvesting capacity, thus enabling the full utilization of the solar spectrum. Surface modification of CQDs is undertaken to improve the optical and electronic properties via surface passivation or functionalization, doping by metal and nonmetal components, and hybrids or nanocomposite synthesis to design CQD-based photocatalysts. CQDs improve the photocatalytic behaviors of some commonly used photocatalysts due to their favorable upconversion photoluminescence and electron transport capabilities. This review aims to present a complete overview of CQDs and recent developments and innovations in the creation of various CQD-based hybrid photocatalysts. Furthermore, the recent significant advances in contaminant degradation are systematically highlighted. Finally, the main problems to be addressed, and the future perspectives to provide a complete picture of CQD-based hybrids.