Studies On The Preparation And Photocatalytic Aactivity Of Novel Photocatalyst

Environmental, energy sources and materials sciences are the three key projects 21th century. One of them is the photocatalysis using oxide semiconductor which associated tightly with those topics. Recently, emiconductor materials have attracted increasing attention to fundamental and applied research in the area of environmental remediation. However, the limitation associated with feasibility and viability of semiconductor photocatalytic oxidation is fast recombination of the photogenerated electron-hole pairs and only semiconductor photocatalyst works efficiently under UV irradiation. Therefore, researchers are thinking about the main problems are how to broaden the range of light-response wavelength of semiconductor catalyst, improve the catalytic efficiency and reduce the catalyst cost.In this paper, two novel photocatalyst nanoparticles Sn-SnO2/C,ZnO-ZnS/C were respectively synthesized by a simple carbothermal reduction. A comprehensive study of the novel photocatalyst nanoparticles were investigated by XRD, XPS, TEM, EDX and other new technologies. The photocatalytic activities of the nanocomposites were evaluated by the degradation process of reactive brilliant blue K-3R. Furthermore, possible growth mechanisms of the two novel photocatalysts were proposed. The main results from those studies are summarized as follow:1. A novel ZnO-ZnS/C photocatalyst has been synthesized by dipping-carbothermal reduction. Optimize the preparation process condition and obtain the best preparation parameters as follows:The loading capacity of Zn is 10%, the heat-treating temperature is 700℃, the heat-treating time is 2h. The research found that the surface composition and structure of ZnO-ZnS/C catalyst can be adjusted by changing preparation conditions. Activated carbon played a very important role for the formation of ZnS. In addition, ZnO and ZnS nanoparticles are intimately contacted on the carrier surface, indicating the ZnO-ZnS heterojunction can be formed. The ZnO-ZnS/C photocatalyst was evaluated by the degradation of reactive brilliant blue K-3R simulating wastewater showed that the photocatalytic activity of the ZnO-ZnS/C photocatalyst was significantly enhanced under the UV and visible light compared with pure ZnO and ZnO/C which showed more excellent photocatalytic activity.2. A novel Sn-SnO2/C photocatalyst has been synthesized by adsorption-carbothermal reduction. Optimize the preparation process condition and obtain the best preparation parameters as follows:The concentration of liquor (SnCl4) is 0.4mol/L, the heat-treating temperature is 800℃, the heat-treating time is 2h. The research found that the Sn-SnO2 heterojunction is built by depositing of metallic Sn on the crystal lattice oxygen of as-formed SnO2 during the heat-treatment process by carbon carrier, which obviously increase amount of adsorbed oxygen on the surface of catalyst. The Sn-SnO2/C was evaluated by the degradation of reactive brilliant blue K-3R showed more excellent photocatalytic activity compared with pure SnO2. The enhancement of photocatalytic performance of Sn-SnO2/C can be attributed to the formation of metallic Sn on the surface of catalysts. The metallic Sn and adsorbed oxygen as the sinks of photoinduced electron and the electronic scavenges, respectively, hinder the recombination of photoexcitated electron-hole pairs, equentially enhance the photocatalytic activity.