Preparation Of R-GO-modified-titanium Dioxide Photocatalysts And Evaluation Of Their Photocatalytic Behavior Under Visible Light Irradiation

Titanium dioxide has important applications in photocatalysis, however, these are limited by its wide bandgap. In this dissertation, we aim at improving photocatalysis of titanium dioxide through two different methods to expand the scope of its light absorption range, so that it can make use of visible light and prohibit the rapid recombination of photo-generated electron-hole. So we add r-GO to increase the separation efficiency of photo-generated electron-hole, thereby enhancing the photocatalytic activity.We use microemulsion-solvothermal method prepare Ti³⁺ self-doped TiO₂. The Ti³⁺ can produce isolated states in the forbidden gap of TiO₂.Therefore it can reduce the energy required for exciting the electron form valence band under visible light irradiation. Meanwhile, in the process of microemulsion-solvothermal reaction, titanium trichloride can reduce the graphene oxide into r-GO and Ti³⁺ are oxidized into Ti4+, and it may generate the spherical nuclei, in the latter part of the solvent thermal processes, crystal particles are grown and ultimately rutile Ti O2 microspheres are formed. We also measure the visible light photocatalytic activity of Ti³⁺/r-GO/TiO₂ microspheres, and study on the photocatalyst mechanism under visible light irradiation.In order to improve the utilization of solar energy, great focus had been taken on constructing heterogeneous structure by introducting a narrow band gap semiconductor with TiO₂ to achieve visible-light photocatalysis. TiO₂ microspheres were prepared by solvothermal method and g-C₃N₄ was added to construct TiO₂- C₃N₄ heterojunction extending the light absorption range in the visible region. In order to overcome the inherent defect of high photo-generated carriers recombination in TiO₂-C₃N₄ heterojunction system, a novel ternary composite of heterostructured g-C₃N₄/r-GO/TiO₂ microspheres were prepared. By usingUV-light to reduced r-GO as the intermediate layer of the g-C₃N₄/TiO₂ microspheres to serve as electron conduction bridge. Furthermore, the photocatalytic activity of g-C₃N₄/rGO/TiO₂ microspheres was measured and the probable photocatalytic mechanism was evaluated under visible light irradiation.