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

Carbon Quantum Dots Induced Ultrasmall BiOI Nanosheets with Assembled Hollow Structures for Broad Spectrum Photocatalytic Activity and Mechanism Insight

Carbon quantum dots (CQDs) induced ultrasmall BiOI nanosheets with assembled hollow microsphere structures were prepared via ionic liquids 1-butyl-3-methylimidazolium iodine ([Bmim]­I)-assisted synthesis method at room temperature condition. The composition, structure, morphology, and photoelectrochemical properties were investigated by multiple techniques. The CQDs/BiOI hollow microspheres structure displayed improved photocatalytic activities than pure BiOI for the degradation of three different kinds of pollutants, such as antibacterial agent tetracycline (TC), endocrine disrupting chemical bisphenol A (BPA), and phenol rhodamine B (RhB) under visible light, light above 580 nm, or light above 700 nm irradiation, which showed the broad spectrum photocatalytic activity. The key role of CQDs for the improvement of photocatalytic activity was explored. The introduction of CQDs could induce the formation of ultrasmall BiOI nanosheets with assembled hollow microsphere structure, strengthen the light absorption within full spectrum, increase the specific surface areas and improve the separation efficiency of the photogenerated electron–hole pairs. Benefiting from the unique structural features, the CQDs/BiOI microspheres exhibited excellent photoactivity. The h⁺ was determined to be the main active specie for the photocatalytic degradation by ESR analysis and free radicals trapping experiments. The CQDs can be further employed to induce other nanosheets be smaller. The design of such architecture with CQDs/BiOI hollow microsphere structure can be extended to other photocatalytic systems

S, N Codoped Graphene Quantum Dots Embedded in (BiO)₂CO₃: Incorporating Enzymatic-like Catalysis in Photocatalysis

In this study, S, N codoped graphene quantum dots/(BiO)₂CO₃ hollow microspheres have been fabricated by a facile electrostatic self-assembly method. The nanosized S, N:GQDs, which can be obtained by a bottom-up approach, are superior surface modification materials for photocatalytic applications due to their better electron transfer and peroxidase mimetic properties. The excellent oxidation property of the synthesized nanocomposite is confirmed by degradation of different model pollutants, such as rhodamine B, tetracycline, and bisphenol A under light irradiation or dark situation. Based on several experiments, the essential roles of S, N:GQDs can be described as (i) a photocarrier transport center strengthening photoinduced charge carriers (h⁺–e^–) separation and (ii) an enzymatic-like catalysis center to accelerate H₂O₂ decomposition to produce ·OH because the surface accumulation of H₂O₂ is harmful for photocatalytic processes. The present work may pave the way for integrating enzymatic-like cocatalysis into a photocatalytic process to generate more reactive oxygen species, thus advancing the field of environmental remediation and synthetic chemistry