Preparation And Application Of Core-shell Photocatalyst Based With CdS Nanoparticles

A problem of the21st century human face and urgent need to solve is environmental pollution. In recent years, photocatalyst become an ideal environment pollution control technology. Because it was discovered that the photocatalytic reaction have many superior performance, such as fast, mild conditions and degradation of organic matter completely. Therefore, the selection and preparation of photocatalyst became our research focus. As a photocatalyst, CdS’s energy gap is narrow, bandgap is about2.4eV, visible light can be excited, and the production cost is low. However, pure CdS is not stable under the condition of the sunlight, prone to light corrosion. And pure CdS have a certain degree of secondary pollution after the catalytic degradation. The above problems can be solved by preparing nanocomposite materials with other materials. In this paper, the main research works are as follows:1. Monodisperse CdS nanoparticles were prepared by60Co y-ray irradiation method with CdCl2·2.5H2O and Na2S2O3·5H2O as raw materials, isopropyl alcohol as a catalyst, PVP as the stabilizer. In addition, the influential factors of the salt concentration and the amount of ethanol on the impact of the morphology, size and size distribution of CdS nanoparticles were studied. XRD and HRTEM spectrum showed that CdS nanoparticles was sphalerite structure. Morphology and monodispersity of CdS nanoparticles was characterized by TEM photographs. By comparing the TEM of CdS prepared under different recipes, the effects of salt concentration and the amount of ethanol on CdS nanoparticles size, CdS nanoparticles size distribution and dispersion was studied.2. Using the as-prepared monodisperse CdS nanoparticles as raw material, core-shell CdS/SiO2nanocomposite microspheres were synthesized by in-situ hydrolysis of TEOS at room temperature. CdS/SiO2nanocomposite microspheres were characterized by FT-IR and TEM. Results show that with different catalysts, alcohol water system, water content and the amount of TEOS, the CdS/SiO2nanocomposite microspheres prepared have different shell thickness. With the increase of water amount or the decrease of TEOS concentration, the SiO2shell thickness varies from28to105nm. The shell thickness of silica could be easily controlled. We focused on the photocatalytic activity of as-prepared CdS/SiO2and the residual Cd2+concentration after photocatalytic degradation of MB. With slight reduction of photocatalytic reactivity, the CdS/SiO2nanoparticles obviously enhance the photo-stability of CdS and reduce the residual concentration of Cd2+in aqueous solution.3. Using the as-prepared monodisperse CdS/SiO2nanoparticles as raw material, with MPS (3-(Methacryloyloxy) propyl trimethoxysilane) modified, core-shell-shell structure CdS/SiO2/PS nanocomposite microspheres was synthesized by dispersion copolymerization method. The morphology of CdS/SiO2/PS nanocomposite microspheres was characterized by TEM, the composition of CdS/SiO2/PS nanocomposite microspheres was analyzed by TGA. The effect of the amount of monomer and crosslinking on the morphology and size of CdS/SiO2/PS nanocomposite microspheres was researched. TEM results show that CdS/SiO2/PS nanocomposite microspheres has core-shell-shell structure, the shell thickness of PS range from28nm to227nm. The shell thickness of PS could be easily controlled. Finally, the CdS/SiO2/PS nanocomposite microspheres photocatalytic degradation of MB experiment under the organic environment was researched, and its photocatalytic performance was studied. Photocatalytic results illustrate that the CdS/SiO2/PS nanocomposite microspheres as photocatalyst have potential application value.In this article, monodisperse CdS nanoparticles, core-shell structure CdS/SiO2nanocomposite microspheres and core-shell-shell structure CdS/SiO2/PS nanocomposite microspheres were successfully prepared with simple methods. And their performance of photocatalytic degradation of organic matter were got a preliminary study, research results indicate that they all have potential application value in reality.