Narrow Results

In this study, direct Z-scheme MnWO₄/g-C₃N₄ photocatalyst was fabricated via facile hydrothermal method. Compared with pristine graphitic carbon nitride (g-C₃N₄) and manganous tungstate (MnWO₄), the prepared MnWO₄/g-C₃N₄ photocatalyst showed obviously enhanced photocatalytic activity for Rhodamine B (RhB) degradation under visible light irradiation. The MnWO₄/g-C₃N₄ photocatalyst prepared with 10% MnWO₄ (MC10%) showed the highest photocatalytic activity among all samples, which is about 2.3 and 12.7 times than that of pristine g-C₃N₄ and MnWO₄, respectively. This enhancement is due to the strong light absorption and efficient electron–hole separation of direct Z-scheme MnWO₄/g-C₃N₄ photocatalyst. Electron spin resonance (ESR) experiments and active species trapping experiments revealed that $•$OH and $•{\mathrm{\text{O}}}_2^{-}$ are the main active species in the photocatalytic process. This work may be beneficial for designing MnWO₄-based Z-scheme photocatalyst for application in environmental remediation.

Double element co-doped carbon quantum dots (CQDs) have unique electron properties and broad prospects in photocatalysis. In this paper, the phosphorus and nitrogen co-doped CQDs (PNCQDs) were loaded on TiO₂ nanosheets by in-situ synthesis method. Physical structure and chemical composition of samples were analyzed by XRD, FT-IR, XPS, SEM and TEM. UV–Vis spectra show the donor–acceptor coupling between PNCQDs and TiO₂ and enhanced strong UV light absorption. Photoluminescence spectra indicate that PNCQDs effectively promote charge separation, which is different from nitrogen doped CQDs. The sample 1-PNCT with the optimal phosphorus doping amount has the highest kinetic constant for photodegradation of Methylene Blue (MB), which is 3.4 times pure TiO₂. A possible Z-scheme photodegradation mechanism is proposed according to the active species scavenge experiment results in which PNCQDs can not only accept but also localize photogenerated electrons to dopant sites due to the quantum wells created by P and N doping energy barriers.

Ag₂S/AgI/Ni composite films were prepared by constant current electrodeposition and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and UV-vis diffuse reflectance spectroscopy. Under visible light (> 420 nm), Ag₂S/AgI/Ni composite film photocatalyst showed higher photocatalytic (PC) activity in the degradation of rhodamine B (RhB) than a pure Ag₂S/Ni film or AgI/Ni film. The composite film demonstrated excellent stability and could be recycled 11 times with an essentially unchanged PC activity. Ag nanoparticles were generated in the PC process and acted as a charge-transfer bridge, forming a $Z$-scheme composed of Ag₂S, Ag, and AgI. This effectively separated the photogenerated electrons and holes, hence providing excellent PC activity and stability to the Ag₂S/AgI/Ni composite film.