二氧化钛光催化一些简单的研究.doc

Overview of Researches of TiO2 梈hang Yu,Li Hao,Zhang Zhaolong Titanium dioxide (TiO2) has been extensively used and investigated as an excellent photocatalyst because of its exceptional properties such as nontoxicity, low cost, and long-term stability against chemical corrosion. In particular, TiO2 has found a wide application in the fields of dye-sensitized solar cells, environmental treatments, sensors, photoinduced hydrophilicity, etc. However, a large intrinsic band gap of TiO2 (3.2 eV for the anatase structure and 3.0 eV for the rutile structure ) allows only a small portion of solar spectrum in the ultraviolet (UV) light region to be absorbed. Therefore, the effective utilization of visible light has become one of the most important goals in photocatalytic applications. The electron(e-) and hole(h+) pairs are generated when TiO2 is irradiated by UV photons with an energy greater than or equal to the band gap energy, and these charge carriers can then migrate to the surface to initiate various redox reactions of the adsorbates. OH- and H2O molecules adsorbed on the TiO2 surface can be oxidized into OH radicals by the h + distributed on the surface, while the OH radical is the strongest oxidant in water there and can oxidize most of organic pollutants and some inorganic contaminants, and the ultimate degradation of CO2, H2O and other harmless substances. As the OH radical pairs of reactants almost no selectivity, and thus in the photocatalytic oxidation plays a decisive role. In addition, many organic oxidation potentials is more negative number than that of TiO2 valence band potential, and can be directly oxidized by h+. The high activity e- on the TiO2 surface, have a strong reduction capacity, and can restore to remove metal ions in water. The reaction as following: There are currently several ways of improving the photocatalytic activity of TiO2 materials, as follows: (1) control of particlesize, crystallinity, and crystalline phases (anatase,rutile,