Carbon Quantum Dots Functionalized g-C3N4 nanosheets as Enhanced Visible-light Photocatalysts for Water Splitting

Abstract Graphitic carbon nitride (g-C3N4) is a representative photocatalyst, but the photocatalytic activity is often limited because of the easy recombination and slow migration of photogenerated charges. Herein, we have successfully prepared carbon quantum dots (CQDs) functionalized g-C3N4 (CCN) by a simple thermal polymerization method. Besides, the CQDs serving as a photosensitizer can enlarge the absorption range of visible light of the composite material. As a result, under the irradiation of visible light, the optimized CCN showed superior catalytic activity with a high H2 production rate of 2321 μmol·g-1·h-1, which was almost about 7.4 times higher than that of bulk g-C3N4. Based on the systematic characterization and density functional theory (DFT) calculation, it was proved that the efficiencies of the separation and transfer of photogenerated charges were enhanced by the micro-regional heterostructure of CQDs and g-C3N4.