TiO2@ graphene quantum dots nanocomposite as an efficient photocatalyst for degradation of RB5 under sunlight irradiation

Herein, we report the facile fabrication of graphene quantum dots (GQDs) NPs, and @GQDs nanocomposite. NPs with the average particle size of 8 nm, band gap of 2.45 eV, and specific surface area of 236 m2 g-1 and /GQDs nanocomposite with the average particle size of 15.60 nm and band gap of 2.23 eV were prepared by one-pot hydrothermal method. The GQDs with the average particle size of 20 nm were prepared via one-step pyrolysis of citric acid. The photocatalytic activity of @GQDs nanocomposite was evaluated by the photodegradation of an azo dye, Reactive Black 5 (RB5) under sunlight irradiation and compared with that of NPs, P25, and GQDs. The results showed that the complete (100.00%) photocatalytic degradation of RB5 dye was achieved by @GQDs nanocomposite compared with that of NPs (99.98 %), P25 (91.16 %), and GQDs (1.55 %) (Fig. 1). The photocatalytic degradation mechanism of RB5 by NPs was evaluated through the addition of 20 mM of different scavengers to the solution. The results showed that is the main oxidant in the photodegradation of RB5.