Carbon quantum dots sensitized 2D/2D carbon nitride nanosheets/bismuth tungstate for visible light photocatalytic degradation norfloxacin

A novel carbon quantum dots (CQDs) sensitized 2D/2D carbon nitride nanosheets and bismuth tungstate composite (CQD-CNs/BWO) was successfully prepared via the facile hydrothermal method and used for the photocatalytic degradation of norfloxacin (NOR). During 120 min irradiation test, CQD-CNs/BWO exhibited 9 and 1.76 times higher photocatalytic activity than CNs and BWO, respectively. CQDs and constructed 2D/2D structure could not only improve the light harvesting but also promote the generation and separation of electron-holes. The existing inorganic ions in solution (e.g. bicarbonate ions, chlorine ions, and sulfate ions) could inhibit NOR degradation. Based on the electron spin resonance and free radicals inhibition tests, the holes and superoxide radicals rather than hydroxyl radicals were the main reactive species. The intermediates and possible pathways were proposed, and the antibacterial activity of the treated solution after the reaction was evaluated via bacteriostatic tests. The prepared composite material with high photocatalytic activity and stability is potentially effective for the degradation of antibiotics in wastewater.