| TiO2 is a kind of semiconductor material with the advantages of low price, strong chemical stability, non-toxic and good reutilization character. While, TiO2 can only be excited by ultraviolet light to generate photo-generated electrons and holes. However, in the sun light, ultraviolet light accounted for only about 5 %, that is to say, when the bandgap of the semiconductor is larger(greater than 3.1 eV), the use of solar energy and artificial light can not be effectively, so that the quantum efficiency of TiO2 is very low. In order to overcome the big weakness of semiconductor, the development of novel visible light driven catalyst has always been the pursuit of the the researchers.Recently, silver based semiconductor photocatalyst has attracted more and more attention because of their surface plasmon resonance effect, especially Ag/AgX(X=Cl, Br) materials, because of their excellent photocatalytic ability, they are widely used in many fields and have attracted researchers’ in-depth study. In this experiment, Ag/AgX(X=Cl, Br) particles were coated on the surface of the TiO2 nanofibers homogeneously through a series of experiments, by controlling the experimental conditions to regulate the size and morphology of the nano-particles. Thus, the method is not only solved the problem of agglomeration of Ag/Ag X, and also lead to surface modification of TiO2 nanofibers. The surface plasmon resonance effect of noble metals, heterojunction structure of Ag-AgX/TiO2 and the synergistic effect of Ag, AgX and TiO2 enhance the absorption of visible light, accelerate the separation of photogenerated electrons and holes and greatly improves the photocatalytic efficiency of the catalyst.In this experiment, we used TiO2 nanofibers prepared by electrostatic spinning as template, synthesized a series of visible light response catalysts of Ag-AgX/TiO2(X=Br or Cl) by ion-exchange and photoreduction method. X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM), scanning electron microscopy(SEM), UV-Vis diffuse reflectance spectra(DRS) and light induced luminescence spectroscopy(PL) methods were used to test the structure, morphology and performance of the prepared catalysts. Using methylene blue and phenol to study the degradation performance of the Ag-AgX/Ti O2 under visible light irradiation and explore the relationship between the structure and photocatalytic properties of the composite photocatalytic materials. Studies have shown that the performance of Ag-AgX/TiO2 heterostructure was much better than that of pure TiO2 and Ag-AgX powder, by the analysis of the catalytic mechanism, the possible explanation is that, in the AgX, part of the Ag+ is reduced to Ag by Photoreduction, with the help of the surface plasmon excitation effect of Ag and the synergistic effect of between Ag, AgX and TiO2, the catalyst can enhance the absorption of visible light, moreover TiO2 nanofibers as the template can increase the specific surface area of the photocatalyst, and is favorable for photocatalytic reaction. In addition, We used repeated experiment to investigate its stability and availability of reusing. The results show that, the prepared catalysts not only exhibits perfect catalytic effect but also possess the advantages of easy recovery, good stability and availability of reusing. |
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