Graphitic-C3N4 quantum dots decorated {001}-faceted TiO2 nanosheets as a 0D/2D composite with enhanced solar photocatalytic activity

Zero-dimensional (0D)/two-dimensional (2D) heterojunctions have attracted great attention in photocatalysis due to their superior interfacial effects. In this work, 0D g-C3N4 quantum dots (CNQDs) were firstly used to modify {001}-faceted 2D TiO2 nanosheets by a simple solvothermal method. During the controlled growth of TiO2 nanosheets with exposed reactive {001} facets, the CNQDs can be simultaneously assembled on the surface of TiO2 nanosheets in a highly dispersive way. The 0D/2D composite containing only 0.5% of CNQDs shows the optimized solar photocatalytic activity for the degradation of rhodamine B and 4-chlorophenol. More importantly, the 0D/2D composite exhibits a better solar photocatalytic activity than the bulk g-C3N4/TiO2 nanosheets composite. This improvement can be ascribed to the close interfacial contact and strong interaction between the highly dispersed CNQDs and the TiO2 nanosheets, which could lead to efficient separation of the photogenerated electron–hole pairs, provide more catalytic active sites, and enhance the absorption of solar light. The 0D/2D composite also shows good stability for its practical applications.