| In this thesis, we prepared cadmium sulfide photocatalysts through solvothermal and hydrothermal method, investigated the photocatalytic hydrogen generation over CdS using fomic acid as an electric donor under visible light. This work is composed of two parts:In the first part, the preparation of nanocrystalline CdS by solvothermal process in the presence of ethylenediamine and its photocatalytic performance were studied. We synthesized CdS photocatalyst by solvothermal method, using ethanol as the solvent and ethylenediamine as the complexing agent. The effects of amount of the complexing agent, the amount of deposited platinum(Pt) and the reaction temperature on the photocatalytic activity of the products were investigated. The samples were characterized by X-ray diffraction(XRD), specific surface area(BET), scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflectance spectra (UV-Vis).The results showed that the photocatalytic activity of the samples were improved greatly via the introduction of ethylenediamine. The possible mechanism was discussed.In the second part, the preparation of CdS by a NasPO4-assisted hydrothermal method and its photocatalytic performance were studied. Using Na3PO4as an assisted agent, a series of samples were synthesized by hydrothermal method. The effects of concentration of Na3PO4, hydrothermal time and Pt loading on the photocatalytic activity of the products were investigated. The samples were characterized by X-ray diffraction (XRD), specific surface area (BET), transmission electron microscopy(TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible diffuse reflectance spectra(UV-Vis) and electrophoretic analysis. The activity and the stability of the products were enhanced greatly when Na3PO4was added. Na3PO4induced the transformation of cubic to hexagonal phase of CdS. It was found that when the concentration of Na3PO4was0.05M, the reaction temperature was180℃, the formed hexagonal phase content reaches a maximum (82%). Pt is dispersed highly on CdS so that the Pt content for the effective hydrogen evolution is very low.0.025%Pt-loaded CdS exhibited the highest activity for hydrogen evolution with the apparent quantum efficiency at420nm amounted to21.4%. This work highlights a facile and low-cost method for preparation of highly-efficient CdS photocatalyst. The possible mechanisms were discussed. |
