| Nanometer ZnO is an important semiconductor material whose bandgap is similar to that of TiO2.However,there were many problems in quantum efficiency, wavelength absorption scope and powder recovery aspects,so the practical applications of photocatalysis technology were limited.In this paper,nanometer ZnO film,nanometer Ag-ZnO film and nanometer ZnO/PVAc composite film were prepared by sol-gel process,dip-coating process and photodeposition method and its properties were characterized by X-ray Diffraction(XRD),Ultraviolet-Visible Absorption Spectroscopy(UV-vis),Field Emission-Scanning Electron Microscopy (FESEM),Fourier Transform Infrared Spectroscopy(FT-IR),X-ray Photoelectron Spectroscopy(XPS),Electron Paramagnetic Resonance Spectrometry(ESR).The photocatalytic activity of the film was tested using methyl orange as the model reaction.(1)Preparation of nanometer ZnO Film and study on its photocatalytic propertyIn this experiment,nanometer ZnO film was prepared by sol—gel process and dip-coating process.Then,the effects of preparation conditions on the photocatalytic property of nanometer ZnO film were investigated.The results indicated that when the calcination temperature was 250℃and the calcining time was 60 min,the photocatalytic property of nanometer ZnO film was the best.Under the irradiation with ultraviolet light,the decolorization proportion of methyl orange was 62%when using pure nanometer ZnO film.FESEM,XRD,XPS,UV-Vis and FT-IR showed that the significant quantum size effect leads to the high photocatalytic activity.(2)Preparation of nanometer Ag-ZnO Film and study on its photocatalytic propertyIn this experiment,Silver-modified nano-ZnO films were prepared by the sol-gel, dip-coating process and photodeposition method.Then,the effects of the concentration of silver nitrate solution and photodeposition time on the photocatalytic property of composite were investigated.Under the irradiation with ultraviolet light, the decolorization proportion of methyl orange is 78%when using the nanometer Ag-ZnO film at a Ag loading of 0.0182mg·cm-2.FESEM,XPS,ESR,UV-Vis and FT-IR showed that the content of adsorbed oxygen(Oa)and hydroxyl oxygen(OH)on the surface of nanometer Ag-ZnO film was increased and the lattice oxygen(O1)was decreased in contrast to that of the pure nano-ZnO film.therefore,photocatalytic activity was enhanced.At the same time,the reasons of the nano-Ag-ZnO film with high photocatalytic activity were explained.(3)Preparation of composite based on nanometer ZnO/PVAc film and study on its photocatalytic propertyIn this experiment,nanometer ZnO/PVAc composite film with high photocatalytic property under visible light irradiation was prepared by sol—gel process and dip-coating process.Then,the effects of PVAc concentration,calcining temperature and calcining time,nanometer ZnO/PVAc composite film numbers,and attachment layer of nanometer ZnO film numbers on photocatalytic property of composite film were studied by orthogonal method.Under the irradiation of incandescent lamp,the decolorization proportion of methyl orange was 60.00%when using nanometer ZnO/PVAc composite film(250℃,30min,PVAcl0%,(1*1)2). SEM,XRD,UV-Vis and FT-IR showed that PVAc stoped the reunion of ZnO particles and made more integral structure of the nano-crystalline ZnO;The main reasons of nanometer ZnO/PVAc composite film with high photocatalytic property were the effect of interfacial diffusion of the composite film and the new structure formed of the composite film after calcinations.
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