| In recent years, semiconductor photocatalyst used in the field of energy and environment is developing rapidly. Amount of papers have reported on WO3semiconductor materials. The WO3semiconductor itself, however, has some defects such as it’s band gap (Eg) is relatively wide and the transferring speed of photogenerated charges of WO3is slow, etc., which limit the actual application of WO3. In order to alleviate the defects of WO3, it is necessary to modify WO3with other materials. Based on the above thoughts, Fe(III), Zn(II) and Cu(II) ions modified WO3thin films were prepared by electrodeposition-impregnation and cyclic voltammetry methods. We preliminary studied the photoelectrochemical properties and photoelectrocatalitic activity on the degradation of organic dyes of the materials and discussed the transferring mechanism of photogenerated charges in the semiconductor materials. This content and innovation of this thesis are listed as following:(1) Preparation of WO3photoelectrodes modified with Fe(III) ion and their photoelectrochemical and photoelectrocatalytical properties. Nanostructured thin film electrodes of WO3were modified with different amount of Fe(III) ions (Fe-WO3) through an electrodeposition-impregnation method, followed by annealing in air at450℃for3h. The samples were characterized by XRD, SEM, EDS and ESR. Results showed that iron species existed in both the form of lattice iron and Fe2O3clusters, the crystal size of WO3decreased upon Fe loading. The Fe-WO3thin film electrode containing1.12at%Fe relative to W atom showed the best performance in photoconversion efficiency for water splitting and photoelectrocatalytic activity for degrading methylene blue (MB), and its photoconversion efficiency and photoelectrocatalytic activity were6.8times and3.4times than those of pure WO3electrode, respectively. The possible mechanism for the improved photoelectrochemical performance of Fe-WO3electrodes was discussed in the text.(2) Preparation of WO3photoelectrodes modified with Zn(II) ion and their photoelectrochemical and photoelectrocatalytical properties. According to the work of the Fe(Ⅲ) modified WO3thin film electrode materials, we adopted the same methods to prepare Zn(II) modified WO3thin film photoelectrodes. The effect of Zn(Ⅱ) content on the structure and morphology of WO3thin film photoelectrodes was researched by XRD, FE-SEM, UV-Vis and PL emission spectra characterization. The photoelectrochemical and photoeiectrocatalytic activity on degradation of malachite green (MG) were tested and the results showed that Zn(II) content in WO3thin film photoelectrodes has significant influence on the photocurrent and photoelectrocatalytic activity. It is proved that part of Zn(Ⅱ) existed in the form of ZnO particles on the surface of WO3based on Raman results, ZnO act the role of capture the holes on the valance of WO3, which is also the reason of the improved photocurrent and photoelectrocatalitic activity.(3) Preparation and the photoelectrochemical performance of Cu(II) modified WO3photoelectrode. Cu(II)-WO3film was prepared by cyclic voItammetry one-step clectrodeposition method, which is simple and highly reproducible. In comparation with the cell parameters between Cu-WO3film and WO3film, it is proved that Cu was penetrated in the lattice of WO3after heating treatment. EDS showed that in Cu-WO3film, the atomic percentage of Cu relative to W is1.43at%and Cu was uniformly distributed in the Cu-WO3film. The photoelectrochemical experiment showed that the current density of Cu-WO3thin film is2times than WO3. PL emission spectra showed that there were less oxygen defects in Cu doped WO3crystals, which improved the photoelectrochemical performance of WO3. |
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