Nitrogen-Doped Carbon Quantum Dots/BiOBr Ultrathin Nanosheets: In Situ Strong Coupling and Improved Molecular Oxygen Activation Ability under Visible Light Irradiation

Novel nitrogen-doped carbon quantum dots (N-CQDs)/BiOBr ultrathin nanosheets photocatalysts have been prepared via reactable ionic liquid assisted solvothermal process. The one-step formation mechanism of the N-CQDs/BiOBr ultrathin nanosheets was based on the initial formation of strong coupling between the ionic liquid and N-CQDs as well as subsequently result in tight junctions between N-CQDs and BiOBr with homodisperse of N-CQDs. The photocatalytic activity of the as-prepared photocatalysts was evaluated by the degradation of different pollutants under visible light irradiation such as ciprofloxacin (CIP), rhodamine B (RhB), tetracycline hydrochloride (TC), and bisphenol A (BPA). The improved photocatalytic performance of N-CQDs/BiOBr materials was ascribed to the crucial role of N-CQDs, which worked as photocenter for light harvesting, charge separation center for separating the charge carriers, and active center for degrading the pollutants. After the modification of N-CQDs, the molecular oxygen activation ability of N-CQDs/BiOBr materials was greatly enhanced. A possible photocatalytic mechanism based on experimental results was proposed.