Hydrothermal synthesis of cobalt-doped ZnS for efficient photodegradation of methylene blue
•Hierarchical coral-like Co-doped ZnS was prepared by hydrothermal method.•Co-doping enhances the absorption of visible light of the ZnS.•Co-doping inhibits the recombination of photoinduced charge carriers.•A 5.49 at.% Co content guaranteed higher photocatalytic activity.
A series of coral-like Co-doped ZnS were synthesized by hydrothermal method and used for efficient photodegradation of methylene blue. The chemical composition and microstructure of the Co-doped ZnS were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, scanning electron microscope, and transmission electron microscopy. The results showed that the Co atoms were incorporated into the Zn-S lattice, forming solid solution-type phase. As the Co dopant concentration increases from 0 to 22.49 at.%, the calculated band gap energy of the doped ZnS decreases from 3.32 to 2.65 eV, which enables stronger absorption of visible light. Furthermore, the Co dopant could act as electron trapping center, which inhibits the recombination of the photoinduced electrons and holes. As such, the Co-doped ZnS micro-corals showed higher photodegradation efficiency for methylene blue compared with pristine ZnS. The optimized photocatalytic activity was achieved on 5.49 at.% Co-doped ZnS.
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Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 325, 1 July 2016, Pages 62–67