Preparation And Performance Study Of Titanium Dioxide Nano-photocatalyst

Environmental pollution and energy shortage is increasingly becoming a seriousproblem to the globe due to advances in industrialization. Photocatalytic degradationpollutants have been suggested as an effective method to solve environmentalpollution problems. Among the various photocatalysts, TiO₂semiconductorhas attracted extensive concern of researchers because of its chemical stability, highoxidizing power, rich source, low cost and non-toxicity. However pure TiO₂can notbe used widely due to its low solar energy utilization rate and low quantum efficiency.In this paper, we study the influence of ion doping, surface sensitization and formingcoupled semiconductor on the surface morphology; chemical composition; crystalstructure and photocatalytic activity of TiO₂. The main results are as follows:（1）Both undoped and La-doped TiO₂samples exhibit anatase structure preparedby sol-gel method. Lanthanum doping decreases the grain size of TiO₂. When La/Timolar ratio x is3%, the absorption light intensity and photocatalytic activity ofLa-doped TiO₂sample reachs maximum under ultraviolet light and visible light.（2）Both undoped and I-doped TiO₂samples were prepared by direct hydrolysismethod. Iodine doping decreases the grain size and shortens the band gap of TiO₂.When the annealing temperature increases, I-doped TiO₂sample grain size increasesand the crystal phase changes from brookite and anatase phase to rutile phase, whichresult in the photocatalytic activity reduces. The photocatalytic activity of I-dopedTiO₂samples annealed at400℃is higher than that of P25under the visible light.（3）Porphyrin sensitization doesn’t change the crystal structure of TiO₂, butsensitization can broaden its absorption spectrum to the visible light. The sensitizedsample can produce more electronic and·OH under visible light irradiation, whichimprove the photocatalytic activity of TiO₂under the visible light.（4）The Ag₃PO₄and Ag₃PO₄-TiO₂composite nano-materials were preparedsuccessfully with precipitation method. Ag₃PO₄can absorb visible light less than500nm. The photocatalytic activity of TiO₂can be significantly improved, when theAg₃PO₄is coupled with TiO₂, which can be contributed to the visible light absorptionand the separation of carrier.