In this paper, carbon quantum dots (CQDs) modified BiOCl ultrathin nanosheets photocatalyst was synthesized via a facile solvothermal method. The structures, morphologies, optical properties, and photocatalytic properties were investigated in detail. The photocatalytic activity of the obtained CQDs modified BiOCl ultrathin nanosheets photocatalyst was evaluated by the degradation of bisphenol A (BPA) and rhodamine B (RhB) under ultraviolet, visible, and near-infrared light irradiation. The CQDs/BiOCl materials exhibited significantly enhanced photocatalytic performance as compared with pure BiOCl and the 5 wt % CQDs/BiOCl materials displayed the best performance, which showed a broad spectrum of photocatalytic degradation activity. The main active species were determined to be hole and O2•- under visible light irradiation by electron spin resonance (ESR) analysis, XPS valence spectra, and free radicals trapping experiments. The crucial role of CQDs for the improved photocatalytic activity was mainly attributed to the superior electron transfer ability, enhanced light harvesting, and boosted catalytic active sites.

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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.

Development of efficient, durable and inexpensive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts with accelerated kinetics and high‐performance remain a grand challenge in the context of reversible metal–air batteries. Herein, the Fe3O4 nanoparticles inside N‐doped hollow mesoporous carbon spheres (N/HCSs) yolk‐shell structure (Fex@N/HCSs) is constructed as an excellent bifunctional electrocatalyst for ORR and OER via an innovative approach. The N/HCSs effectively control and confine in situ growth of Fe3O4 nanoparticles using the melting‐diffusion strategy via capillary force and significantly improve the conductivity and structural stability of the hybrid material. The constructed yolk‐shell structured Fe20@N/HCSs ecosystem with Fe–Nx active sites exhibits excellent ORR and OER activity and stability, which even surpass commercial grade Pt/C, RuO2, IrO2 and many reported catalysts. Moreover, the zinc–air battery assembled with Fe20@N/HCSs as a cathode achieves high open circuit voltage (1.57 V), large power density (140.8 mW cm−2), and excellent long‐term cycling performance (over 300 h), revealing superior performance compared to commercial Pt/C + RuO2. This work provides a new avenue for the design and optimization of other high‐performance yolk‐shell materials with nanoscale confinement structures.

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.

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This study describes a promising sunlight-driven photocatalyst for the treatment of ofloxacin and other fluoroquinolone antibiotics in water and wastewater. Perylene diimide (PDI) supramolecular nanofibers, which absorb a broad spectrum of sunlight, were prepared via a facile acidification polymerization protocol. Under natural sunlight, the PDI photocatalysts achieved rapid treatment of fluoroquinolone antibiotics, including ciprofloxacin, enrofloxacin, norfloxacin, and ofloxacin. The fastest degradation was observed for ofloxacin, which had a half-life of 2.08 min for the investigated conditions. Various light sources emitting in the UV−vis spectrum were tested, and blue light was found to exhibit the fastest ofloxacin transformation kinetics due to the strong absorption by the PDI catalyst. Reactive species, namely, h + , 1 O 2 , and O 2•− , comprised the primary photocatalytic mechanisms for ofloxacin degradation. Frontier electron density calculations and mass spectrometry were used to verify the major degradation pathways of ofloxacin by the PDI−sunlight photocatalytic system and identify the transformation products of ofloxacin, respectively. Degradation mainly occurred through demethylation at the piperazine ring, ketone formation at the morpholine moiety, and aldehyde reaction at the piperazinyl group. An overall mechanism was proposed for ofloxacin degradation in the PDI−sunlight photocatalytic system, and the effects of water quality constituents were examined to determine performance in real water/wastewater systems. Ultimately, the aggregate results from this study highlight the suitability of the PDI−sunlight photocatalytic system to treat antibiotics in real water and wastewater systems.

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