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Controllable Preparation of Bismuth-based Composite Semiconductors in Solution Phase and Photocatalytic Properties Study

Author: GuanMeiLi
Tutor: HuangShaoMing；MaDeZuo
School: Wenzhou University
Course: Physical and chemical
Keywords: bismuth-based semiconductor composite materials solution-phase synthesis heterojunction photocatalytic properties
CLC: O643.36
Type: Master's thesis
Year: 2011
Downloads: 132
Quote: 1
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Abstract


This paper was committed to study preparation, characterization and photocatalytic properties of bismuth-based composite materials. The main research work is listed as the following parts:（1） Hollow olive-shaped BiVO4 microspheres was successfully synthesized in the presence of AOT under mixed solvothermal conditions at 160 oC for 18 h on a large scale. Furthermore, core-shell BiVO4@Bi2O3 was obtained by thermal solution etching route, employing olive-shaped BiVO4 as precursors. The as-obtained products were characterized by X-ray diffraction （XRD）, Field-emission scanning electron microscope （FE-SEM）, Transmission electron microscope （TEM）, BET specific surface area, and UV-vis diffuse reflectance spectroscopy in detail. The influences of surfactant and the ratios of mixed solvents on the resultant products were systematically surveyed. The formation process of hollow olive-shaped BiVO4 was investigated through the X-ray diffraction analyses and scanning electron microscope observations of the intermediate products at the different reaction stages. The photocatalytic properties of the as-obtained hollow olive-shaped BiVO4 and core-shell BiVO4@Bi2O3 were compared. The results indicated that core-shell BiVO4@Bi2O3 exhibited much higher photocatalytic activities than pure olive-shaped BiVO4. The mechanism of enhanced photocatalytic activity of core-shell BiVO4@Bi2O3 was proposed on the basis of theoretical calculation.（2） Bi2S3/BiVO4 composite photocatalysts were successfully synthesized through a chemical conversion route under hydrothermal conditions, employing olive-shaped BiVO4 as precursors and Thioacetamide （TTA） as sulfur resource. The as-obtained products were characterized by X-ray diffraction （XRD）, Field-emission scanning electron microscope （SEM）, UV-vis diffuse reflectance spectroscopy, Photoluminescence spectra and EDX spectra in detail. The photocatalytic properties of the as-obtained BiVO4 and Bi2S3/BiVO4 composite photocatalysts were compared. The results indicated that Bi2S3/BiVO4 composite photocatalysts exhibited much higher photocatalytic activities than pure BiVO4. It was found that Bi2S3/BiVO4 composite semiconductor prepared with molar ratio of BiVO4: TAA=1:0.4 shows the best photocatalytic acticity. Combined with theoretical calculation of band-edge positions of the two semiconductors, the mechanism of enhanced photocatalytic activity of Bi2S3/BiVO4 was proposed.（3） Bi2WO6/CNTs composite photocatalysts were synthesized under hydrothermal conditions, using carboxylated carbon nanotubes as supports. The as-obtained products were characterized by X-ray diffraction （XRD） and Field-emission scanning electron microscope （FE-SEM） in detail. The influence of the concentration of reactants on the morphology of resultant products was studied by field-emission scanning electron microscope. The photocatalytic results shows Bi2WO6/CNTs nanocomposite materials have good photocatalytic performance on the degradation of Rhodamine B under visible-light irradiation （λ>400nm）.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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