Synthesis, Characterization And Photocatalytic Properties Studies Of Semiconductor Nanostructure Materials By Doping Nonmetal

Semiconductor photocatalysts have attracted much interest due to their potential applicability in degradation of environmental pollutants and solar energy conversion recently. Semiconductor photocatalytic technology overcomes many disadvantages of traditional methods after its appearance. However, its industrial application is hampered because the photocatalytic activity and solar utilization is not high enough for the requirements of practical application. Over the past several years, considerable effert has been made to extend the absorption of semiconductor photocatalysts. Among these modifications, the doping of nonmetal atoms has been proved to be an effective method.On the base of works in the past, in this paper, ZnWO4 and In2O3 were choosed as study objects because of their fascinating properties. ZnWO4 and In2O3 nanostructured was synthesized using hydrothermal synthesis technology's advantages in controlling the materials microstructures, morphologies and size and the photocatalytic activity was enhanced via doping nonmetal atoms.The detailed information of the dissertation is listed as follows:1. Synthesis of nanowires ZnWO4. ZnWO4 nanowires were sucessfully synthesized without any surfactant through a simple hydrothermal route. The ZnWO4 nanowires had a length over 600 nm and a diameter of 10-20 nm. Based on the experment result, the pH value and time of the system played an important role on the morphology of the products. We investigated the growth process of the nanowires and found the "Ostwald-ripening process" played an important role. The photocatalytic activites for aqueous RhB of samples were investigated, and it was amazing that nanowires exhibited a strong photocatalytic activity.2. Synthesis and study the photocatalysis of Fi-ZnWO4. We present a combined study of the photocatalysis of the F interstitially doped ZnWO4 (Fi-ZnWO4) nanocrystals by means of experiment and DFT band structure calculations. The Fi-ZnW04 nanorods were prepared via a two-step hydrothermal process by adjusting the pH of the reaction solution. The results showed that the Fi-ZnWO4 samples exhibited stronger absorption in the UV-visible range with a red shift in the band gap transition. The photo catalytic activity of the F;-ZnW04 samples was highly enhanced for the photocatalytic decomposition of RhB under ultraviolet light irradiation. The morphology and crystallinity of Fi-ZnWO4 have a significant influence on the photocatalytic activity, the Fi-ZnWO4 nanorod showed much higher photocatalytic activity than the nanoparticle one. The DFT calculations show that the interstitially doped fluorine impurities induce the formation of localized states in the band gap. Excitations from these localized states to the conduction band may account for the absorption edge shift toward lower energies observed in the experiment. Calculations also show that fluorine doping leads valance band of ZnW04 move about 0.32 eV to lower energy compared with pure phase, which indicates a stronger hole oxidation ability for the photocatalytic reaction. The excellent agreement between the measured spectra and calculated band can provide a solid basis for understanding of the enhanced photocatalytic activity of Fi-ZnWO4 nanocrystals.3. Synthesis and study the photocatalysis ofⅠ-In2O3 nanorods. In(OH)3 nanorods were successfully prepared through a hydrothermal process at 120℃. Calcination of the In(OH)3 nanorods yielded pure In2O3 nanorods andⅠ-In2O3 nanorods. The nanorods had a length about 300 nm and a diameter of 20 nm. The as-preparedⅠ-doped In2O3 showed high efficiency for the photocatalytic decomposition of MB under visible light irradiation.