Synthesis And Application Of Binary Metal Oxides/Sulfide Photocatalyst

Nowadays, much attention has been paid for environmental purification usingsemiconductor photocatalysts. The first task of the photocatalytic research should be thedevelopment of high efficient photocatalyst. At present time, Semiconductor oxide （e.g.TiO2） has been widely applied in photocatalysis field, because of its non-toxity, low costand strong stability in aqueous media. However, these traditional photocatalysts havemany disadvantages such as low quantum efficiency and narrow range of spectrumresponse, which has seriously hindered their application in many fields. For this reason,it is extremely urgent for us to develop new types of photocatalysts with high efficiencyand full use of the solar energy. In this thesis, to resolve the problems mentioned above,we have finished the following three works:（1） Highly crystalline metastable bismuthtitanate （Bi20TiO32） nanosheets are prepared via a simple green wet chemical route forthe first time. We doped the Bi20TiO32nanoflakes with noble metal （e.g. Au）, which cangreatly enhance the photocatalytic activity of Bi20TiO32by reducing the fastrecombination of the photogenerated charge carriers.（2） Er³⁺doped Bi₂MoO₆nanosheets with enhanced photocatalytic activity were synthesized for the first timeusing a simple hydrothermal method.（3） A series of novel photocatalyst with peculiarmorphology were prepared and they have been successfully applied to photocatalysis.The whole thesis includes five chapters:Chapter1, we reviewed the research progress of semiconductor photocatalysis, andthe principle of the photocatalysis on semiconductor was described in detail in thischapter. Furthermore, we introduced several approaches to enhance the photocatalyticactivity of photocatalysts.Chapter2, we reported a novel and general synthetic strategy to prepare highlycrystalline metastable bismuth titanate （Bi20TiO32） nanosheets via a simple green wetchemical route for the first time. For the catalyst, the size of nanosheets can be wellcontrolled. Inspiringly, the photocatalyst showed high-efficiency and ultrastability forthe degradation rate of X-3B higher than that exhibited by the commercial P25. We doped the Bi20TiO32nanoflakes with noble metal （e.g. Au）, which can greatly enhancethe photocatalytic activity of Bi20TiO32by reducing the fast recombination of thephotogenerated charge carriers.Chapter3, we have demonstrated successfully one-pot wet chemical synthesis ofEr³⁺doped Bi₂MoO₆nanosheets with enhanced photocatalytic activity were synthesizedfor the first time using a simple hydrothermal method. TEM analysis shows that thesenanosheets were selectively exposed {010} facets as the main external surfaces and thenanowires grew along the （010） direction. The activities of the Er³⁺doped Bi₂MoO₆nanosheets were much superior to that of commercial Degussa P25. The effect of Er³⁺on the photocatalytic activity of Bi₂MoO₆was investigated in detail. The enhancedphotocatalytic activity of Bi₂MoO₆nanosheets can be attributed to the exposed {010}facets and the dopant Er³⁺which can transform visible light into ultraviolet light.Chapter4, Novel flowerlike SnO₂nanopaticles embellished SnS₂nanosheetshybrid architectures were synthesized via a one-pot solvothermal process using SnCl45H2O and CH4N2S as precursors. The as-prepared nanocomposite （NCs） exhibitedexcellent photocatalytic activity under visible light. The band-gap of SnS₂@SnO₂canbe easily tuned by the controlled experimental strategy. Anisole and ethanol withdifferent volume ratios were used as binary solvent to tune the composition ofSnS₂@SnO₂NCs continuously and the composites gradually change from hexagonalSnS₂into tetragonal SnO₂.Chapter5, In view of the above problems, in order to promote the practicalapplication of photocatalytic technology, improve the photocatalytic activity andstability of novel photocatalyst, we provides some new ideas on the design of novelphotocatalyst and the development direction of photocatalysis.