Preparation And Photocatalytic Property Of CDS And Its Composites

Semiconductor photocatalysts are widely used in sewage treatment owing to completely decomposing organic pollutants. CdS nanomaterials have narrow band gap and can be able to respond to visible light, thus becaming research hotspot in recent years. In order to improve the photocatalytic ability of CdS nanomaterials and inhibit the light corrosion, CdS composites were prepared by chemical bath deposition method and polyolmenthod. In this thesis, CdS nanomaterials and its nanocomposites have been considered as the objects and synthesized by polyol process. The samples are characterized by XRD, FESEM, EDS, FTIR. Besides, we studied the effect of various factors on the structure, morphology and the photoactivity of the samples and the detailed contents are as the following three aspects:(1) CdS nanomaterials are successfully prepared by the chemical bath deposition method. XRD results showed that CdS is cubic crystal and hexagonal crystal. The influence of the concentration of NH3·H2O and NH4Cl on morphology and photocatalytic properties of CdS nanomaterials are studied. When NH4Cl is fixed1.5g, with increasing the concentration of NH3·H2O, flower-like CdS became thiner. Specifically, the amount of spherical CdS nanoparticles increases with the increasing NH3·H2O. When the volume of ammonia is fixed10ml, spherical CdS nanoparticles become smaller and serious agglomeration with the increasing concentration of NH4Cl.(2) CdS/T-ZnOw composites were prepared via the chemical bath deposition method and polyol method. In this system, the influence of the Cd/Zn molar ratio and the concentration of NH4Cl on the composites morphology and photocatalytic properties were studied. When the concentration of NH4Cl is fixed0.017mol/L, CdS nanoparticles increases with the increasing Cd/Zn molar ratio and serious agglomeration of CdS particles was also found, which resulted in the decrease of photocatalytic properties; when Cd/Zn molar ratio is0.1%, CdS nanoparticles evenly distributed and the amount of CdS reduced. The concentration of NH4Cl is2.99mmol/L, photocatalytic properties of the sample is the best. In the system of Polyol preparation of CdS/T-ZnOw, when PVP content is fixed0.02g, amount of CdS nanoparticles increases and reunion was found with the increasing Cd/Zn molar ratio. When Cd/Zn＜0.57%, the photocatalytic performance increase with the increasing Cd/Zn molar ratio. The photocatalytic performance is getting worse when further increasing the ratio values. When Cd/Zn=0.57%, PVP is less than or equal to0.06g, with the increaseing of PVP, CdS deposition becomes uniform, photocatalytic properties getting better; when PVP continues to increase, the mean size of CdS nanoparticles will become small and evenly distributed.(3) CdS nanoparticles are sueeessfully deposited on the surface of MWCNTs by using Chemical bath deposition method. The influence of MWCNTs mass fraction and NH4CI concentration on the material morphology and photocatalytic performance were investigated. When ammonium chloride concentration is fixed0.05mol/L, amount of CdS nanoparticles fabricated reduces with the decreasing of Cd2+concentrations, and the reunion of CdS nanoparticles to be restrained effectively; When MWCNTs mass fraction＞9%, photocatalytic performance decreased with the increasing of MWCNTs. When MWCNTs mass fraction is9%, amount of CdS deposited decreases with the increasing of NH4Cl concentration. When NH4Cl concentration is less than0.064mol/L, the photocatalytic properties get better with the NH4Cl concentration increases.Bath deposition method and polyol process are simple and the reaction temperature low. Through comparation of the photocatalytic performance of CdS composites with different morphologies, we believe that the morphology have an important impact on the photocatalytic properties of composites.