Preparation And Photocatalytic Properties Of Titanium Dioxide Composites

With the increasingly serious problem of environmental pollution, photocatalytic technology as a new way to deal with water pollution has become a chemistry and materials science research hotspots. Traditional photocatalyst TiO₂ can only be excited by ultraviolet light, so the utilization of solar energy is very low. Bi₂WO₆ and TiO₂ semiconductor composite can broaden the spectral response of TiO₂. β-cyclodextrin has a strong adsorption ability toward various organic molecules due to its hydropobicity. Hence, the adosrptoion capabiliy of the Bi₂WO₆/TiO₂ photocatalyst f or pollutants can be improved if the catalyst surface is modified with β-cyclodextrin. Further more, catalytic efficiency of TiO₂ was restricted by the carrier recombination. While electrons and holes can be effectively separated in case of graphene’s high specific carrier transmission speed. Graphene’s high surface area provides more active sites for the surface reaction. TiO₂ supported on the three-dimensional structure of graphene also recovered for reuse more easily. The main contents of this thesis are as follows:First, Bi₂WO₆/TiO₂ composites were fabricated through hydrothermal methods. The photodegradation of methylene blue dye was employed to evaluate the photocatalytic activities of the Bi₂WO₆/TiO₂ composites under simulated sunlight irradiation. It is demonstrated that when the molar ratio of TiO₂ and Bi₂WO₆ is 6: 1, the material show the highest photocatalytic activities. To prepare Bi₂WO₆/TiO₂/CM-β-CD composite, the adsorption properties of Bi₂WO₆/TiO₂/CM-β-CD was greatly enhanced.Second, the graphene oxide was prepared by modified Hummers method. Then the graphene oxide and TiO₂ were assembled by adjusting the electrostatic interaction. The assembled composites were supported on melamine foam, then three-dimensional graphene and TiO₂（3D r GO/TiO₂） composites were prepared by the way of calcination. The photodegradation of methylene blue dye was employed to evaluate the photocatalytic activities of the 3D r GO/TiO₂ composites under ultraviolet light irradiation.The results show that when graphene oxide and titanium dioxide mass ratio of 1: 1.5,the material show the highest photocatalytic activities. In addition, the 3D r GO/TiO₂ composites can easily be separated for reuse and maintaining high photocatalytic activity.