Studies On Preparation, Modification And Photocatalytic Performance Of Sulfide Semiconductor Photocatalysts

In this thesis the preparation and modification of sulfide semiconductor photocatalyst as well as its photocatalytic performance for hydrogen production were searched.The reseach work is composed of two parts:In the first part the preparation of Composite of SiO₂ and Pt-Cd_0.53Zn_0.47S solid solution and its photocatalytic performance were studied.Cd_0.53Zn_0.47S was prepared by a coprecipitation method.Pt was loaded onto Cd_0.53Zn_0.47S by photodeposition method.SiO₂ was covered onto Cd_0.53Zn_0.47S by hydrolysis of the tetraethylorthosilicate(TEOS),and the effect of the hydrolysis pH on the activity of the catalysts was studied.The samples were characterized by X-ray diffraction(XRD), BET,Photoluminescence(PL),UV-Vis diffusive reflectance spectroscopy(UV-Vis DRS),and scanning electron microscope(SEM) techniques.The composite SiO₂ prevents effectively photocorrosion and coalescence of Pt-Cd_0.53Zn_0.47S nanoparticles during the photocatalytic reaction,and improve the charge separation of photogenerated electrons and holes.Therefore,the stability and the activity of Pt-Cd_0.53Zn_0.47S for photocatalytic hydrogen generation under visible light irradiation were improved greatly.In the second part the preparation of CdS nanorods and its photocatalytic performance were studied.One dimensional CdS nanorods were synthesized by a hydrothermal method using ethylenediamine(EDA) as a complexing agent and characterized by transmission electron microscopy(TEM),X-raydiffraction(XRD), BET and UV-Vis absorption spectra techniques.It was revealed that the reaction time, the molar ratio of precursors,and temperature can control the size and morphology of prepared CdS.The effect of deposited Pt on photocatalytic hydrogen production activity has been investigated.It has been found that when at molar ratio of EDA to Cd²⁺ of 2.0 and at the reaction temperature 150℃,0.05 wt%Pt-loaded CdS exhibited the highest activity for H₂ evolution with the apparent quantum yield at 420 nm amounted to 13.9%.