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In this paper the influence of ZnO shell thickness on the luminescence properties of Mn-doped ZnS nanoparticles is studied. Transmission electron microscopy (TEM) images showed that the average diameter of ZnS:Mn nanoparticles is around 14 nm. The formation of ZnO shells on the surface of ZnS:Mn nanoparticles was confirmed by X-ray diffraction (XRD) patterns, high-resolution TEM (HRTEM) images, and X-ray photoelectron spectroscopy (XPS) measurements. A strong increase followed by a gradual decline was observed in the room temperature photoluminescence (PL) spectra with the thickening of the ZnO shell. The photoluminescence excitation (PLE) spectra exhibited a blue shift in ZnO-coated ZnS:Mn nanoparticles compared with the uncoated ones. It is shown that the PL enhancement and the blue shift of optimum excitation wavelength are led by the ZnO-induced surface passivation and compressive stress on the ZnS:Mn cores.

Visible-light-driven Cr-doped SrTiO 3 nanocubes were successfully synthesized by hydrothermal method in alkaline KOH conditions. X-ray diffraction spectroscopy (XRD), Raman spectra, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize the samples, and the Cr-doped SrTiO 3 possess cubic morphology with about 30-50 nm in size, and single-crystal feature. In addition, the Cr-doped SrTiO 3 extended light-harvesting properties to visible-light region which was testified by UV-vis absorption spectra, and excellent charge transfer and separation efficiency were approved by photo fluorescence spectra (PL), electrochemical impedance spectroscopy (EIS) and photocurrent response measurements. Among the synthesized photocatalysts, SrTiO 3 nanocubes doped with 2% Cr by molar ratio exhibits the highest photocatalytic activity, achieving 11.66 μmol of H 2 evolution during 5 h visiblelight irradiation. This study provides a facile and effective way to enhance the performance of SrTiO 3 -based photocatalysts.

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Heterostructured photocatalysts play a significant role in the removal of contaminants by decreasing the recombination of the photo-induced charges. Herein, we presented novel TiO 2 /C/BiVO 4 ternary hybrids employing a 2D layered Ti 3 C 2 MXene precursor, overcoming the lattice mismatching of TiO 2 /BiVO 4 binary heterostructures simultaneously. Raman and XPS analyses proved the strong coupling effects of TiO 2 , carbon and BiVO 4 components, and the heterostructures were identified from high-resolution transmission electron microscopy results. Moreover, the ternary TiO 2 /C/BiVO 4 composites exhibit excellent photocatalytic performance of Rhodamine B degradation, which is about four times higher than pure BiVO 4 and twice that of binary TiO 2 /BiVO 4 heterostructures, reaching a reaction constant of 13.7×10 −3 min −1 under visible-light irradiation (λ>420 nm). In addition, for the possible mechanism for dye elimination it was proposed that RhB molecule be directly oxidized by photo-induced holes (h + ) on the BiVO 4 components and superoxide radical ( - •O 2 ) generated from conduction band electrons of the heterostructures. This work will provide possibilities for developing visible-light responsive nanomaterials for efficient solar utilization.