Preparation And Characterization Of ZnS-ZnIn₂S₄ And Its Photocatalytic Performance For Hydrogen Generation In The Presence Of Glucose Visible Light Irradiation

In this thesis, we prepared ZnS coated ZnIn2S4 (ZnS-ZnIn2S4) photocatalysts by two methods, investigated photocatalytic hydrogen generation over ZnS-ZhIn2S4 using glucose as an electron donor, and discussed the possible mechanism. The reseach work is composed of two parts:In the first part, ZnS coated ZnIn2S4 (ZnS-ZnIn2S4) photocatalysts were prepared in methanol by a facile solvothermal process. The photocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), UV-vis diffusive reflectance spectroscopy (DRS), BET, and electrochemical measurements. ZnS-ZnIn2S4 photocatalysts had hexagonal crystal phase and complex morphology such as micro-spheres, micro-tubes and micro-ribbons. Using glucose as an electron donor, photocatalytic hydrogen generation over Pt/ZnS-ZnIn2S4 was investigated. The results showed that photoactivity of hydrogen generation over Pt/ZnS-ZnIn2S4 was improved notably with simultaneous degradation of glucose. The factors which affected photocatalytic hydrogen generation, such as composition of ZnS-ZnIn2S4, initial concentration of glucose and concentration of NaOH, were investigated. The prepared ZnS-ZnIn2S4 photocatalysts exhibited better activity for hydrogen generation than pure ZnIn2S4, which may be attributed to enhancement of the adsorption of glucose by ZnS on the ZnIn2S4 surface. The effect of glucose concentration on the hydrogen generation rate is consistent with a Langmuir model. A large number of·OH radicals was generated in the ZnS-ZnIn2S4 system, which have been tested by a TA-FL (terephthalic acid-fluorescence) method. A possible mechanism was discussed.In the second part, ZnS coated ZnIn2S4 (ZnS-ZnIn2S4) photocatalysts were prepared by a facile hydrothermal method. The photocatalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis diffusive reflectance spectroscopy (DRS), and BET. By comparing their photocatalytic activity and property. It was revealed that ZnS-ZnIn2S4 photocatalysts prepared by hydrothermal method were different from that by solvothermal method. The photocatalysts are composed of micro-spheres, but not of micro-tubes and micro-ribbons. Besides, they had smaller BET, so their photocatalytic activity was lower. In addition, they had the best photocatalytic activity when the photocatalyst composition was ZnS(40 mol%)-ZnIn2S4.