| With the development of economy,science and technology,environmental pollution has become more and more serious.In recent years,environmental problems have been paid more and more attention.Semiconductor materials have been widely used in environmental pollution treatment,such as ZnO,CdS,TiO2,Fe2O3,Bi12TiO20,etc.,in these semiconductor materials,because of its rich source,low price,non-toxic,chemical stability,good photocatalytic performance And so the advantages of researchers to become a hot spot.TiO2 can photocatalytic degradation of most organic matter,the degradation products for CO2,H2 O and inorganic acids and other substances,no secondary pollution,thus becoming the most promising new energy in the 21 st century.However,the forbidden band width of TiO2 is 3.23 eV,which can only absorb ultraviolet wavelength.It has low utilization rate of visible light,and it is easy to be compounded and recovered difficult,so it is limited in practical application.Therefore,the researchers have done further research on the above problems,including the inclusion of metal elements,non-metallic elements,deposition of precious metal elements,and semiconductor composite methods to modify the TiO2,can increase its absorption in visible light,slow down the photoelectron-Hole-to-compound rate,and easy recovery after photodegradation.Modification of the synthesis methods are mainly sol-gel method,hydrothermal method,microwave-assisted method,solution combustion method.In this study,the preparation of Sr,Y Ag-doped TiO2 nanomaterials by microwave-induced combustion method and its photocatalytic performance were studied.The conclusions are as follows:(1)Using urea as fuel,butyl titanate as titanium source and oxidant,Strontium nitrate as dopant ion,microwave-induced combustion method was used to prepare Sr-doped titania nanomaterials and characterized by XRD,FT-IR,SEM,XPS,UV-Vis.XRD indicates that Sr is favorable for anatase formation and suppresses grain crystallization.SEM shows that the sample has a larger specific surface area after doping.XPS indicates that the Ti element is present in the form of Ti4+ and the Sr element is present as Sr2+.UV-Vis diffuse reflectance indicates that the strip width of the sample is less than 3.2eV,indicating that the sample can absorb visible light.The effect of doping amount on the photocatalytic efficiency of the sample was studied by the concentration of 20mg/L methyl orange solution in UV irradiation.The results showed that the degradation rate of pure TiO2 was 52.4%,and the photocatalytic efficiency of pure Sr was higher than that of pure TiO2,and the photocatalytic efficiency increased first and then decreased with the increase of Sr content.When the Sr content is 0.5%,the maximum photocatalytic efficiency is 95.6%.When the Sr content is 1.0%,the photocatalytic degradation rate is 93.4%.(2)Using urea as fuel,butyl titanate as titanium source and oxidant,Yttrium nitrate as dopant ion,Y-doped titania nanomaterials were prepared by microwave-induced combustion method.X-ray diffraction was used to characterize the formation of anatase phase and inhibit grain growth.The UV-Vis diffuse reflectance indicates that the resulting sample is partially absorbed in the visible range.Under the ultraviolet light,the catalytic degradation concentration was 20 mg/L methyl orange for 20 min,and the catalytic efficiency of the samples doped with Y was more than 90% Degradation efficiency(degradation rate: 52.4%),and with the increase of Y content,the photocatalytic efficiency increased first and then decreased.When the amount of Y was 1.5%,the catalytic effect was the best,the degradation rate was 95%.When the amount of Y was 2.0%,the degradation rate was 91.5%.(3)Using urea as fuel,butyl titanate as titanium source and oxidant,silver nitrate as dopant ion,microwave-induced combustion method was used to prepare Ag-doped titania nanomaterials and characterized by XRD,FT-IR,SEM,XPS and UV-Vis sample.XRD results show that the prepared samples are mixed crystal and Ag can inhibit the formation of rutile phase.SEM results show that the morphology of the samples after doping was more dispersed and was fine granular.XPS characterization of the Ag element in the doped sample is present in the form of Ag0.UV-Vis indicates that the sample has a sharp red shift and has a strong absorption in the visible region.Under the ultraviolet light,the degradation concentration was 20 mg / L methyl orange solution for 20 min,the effect of doping amount on the photocatalytic effect was investigated.The photocatalytic efficiency was the highest when the amount of doping was 1.0%,and the degradation rate was 98.1%.Under visible light,degradation 20 mg / L methyl orange solution for 3h,the results showed that the photocatalytic efficiency increased first and then decreased with the increase of silver content.When the silver content was 1.0%,the catalytic efficiency was the best,and the degradation rate was 82.7%.When the silver content was 1.5%,the degradation rate was 77%. |
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