Study On Solvothermal Preparation Of Metal-doped Nano-TiO₂ And Its Application Performance

With the continuous growth of global population and the rapid development of industry in recent years,the problems of environmental pollution and energy shortage have become increasingly prominent.In order to ensure the long-term sustainable development of human society,it is urgent to develop environmentally friendly and renewable technologies that can be applied to green energy production and environmental protection.As a representative photocatalyst,titanium dioxide has many advantages,such as stable physical and chemical properties,wide sources,low cost and low energy consumption.However,the band gap of anatase titanium dioxide is 3.2eV,which can only absorb ultraviolet light with wavelength less than 387.5nm,the rapid recombination of photogenerated electrons and holes will reduce the photocatalytic efficiency,which limits the practical application of TiO2 photocatalyst.Therefore,it is necessary to develop high-efficiency photocatalysts,improve the separation efficiency of photogenerated electrons and holes,and reduce their recombination rate,so that the photocatalytic reaction can occur under visible light conditions.This topic mainly prepares single metal element-doped TiO2 and metal element co-doped TiO2 by solvothermal method.The main research contents and conclusions of the topic are summarized as follows:1.The single metal element doped nano-TiO2 was prepared by solvothermal method.The effects of five doping elements of Bi,Fe,Ce,Pr,La and different doping amounts on the physical and chemical properties and photocatalytic performance of TiO2 are mainly studied.The results of XRD and Raman tests show that the crystalline phase of the prepared TiO2 is anatase under the doping elements and doping amounts selected in this topic.SEM and TEM results show that the prepared TiO2 is nanoparticles with a size distribution of 10-30 nm,and the EDS results show that the elements are successfully doped on TiO2.UV-Vis DRS results show that the absorption edge of partially doped TiO2 has red-shifted or the absorption in the visible light band has increased.The results of fluorescence spectra show that the fluorescence intensity of doped TiO2 samples is lower than that of undoped TiO2,indicating that doping is beneficial to reduce the recombination rate of photogenerated carriers.The results of Zeta potential test and dispersion stability test show that the doped samples still have relatively good dispersion performance.The photocatalytic test showed that the visible light catalytic performance of the doped TiO2 sample has a certain improvement compared with the undoped TiO2.Among them,the 0.75%Ce doped sample has the strongest photocatalytic performance,and 3h visible light degrades methyl orange(MO).In the experiment,the degradation rate increased from 20.4%of the undoped sample to 67.4%.2.On the basis of single element doping,further experiments are carried out by solvothermal method,Three combinations of Ce-La,Ce-Pr and Pr-La were selected for the preparation of co-doped nano-TiO2 to study the effects of different co-doping combinations and doping amounts on the properties of TiO2.The XRD test results found that the crystal phase of the co-doped sample is still anatase.SEM results show that TiO2 is still maintained in the range of 10-30 nm,The EDS results show that the two elements selected for co-doping are both present on TiO2,UV-DRS shows that,compared with undoped samples,the light absorption of co-doped samples in the visible light band has increased.The results of fluorescence spectroscopy showed that the fluorescence intensity of some co-doped samples was lower than that of undoped and single-doped samples,which proved that co-doping reduced the recombination rate of photogenerated carriers.Zeta potential results show that the co-doped samples still maintain a certain degree of dispersion stability.The photocatalytic experiment found that the photocatalytic performance of the co-doped samples was higher than that of the undoped samples,and the photocatalytic performance of Ce-La co-doped TiO2 was further improved compared with Ce-doped TiO2 and La-doped TiO2.In the 3h visible light degradation experiment of methyl orange(MO),the degradation rate of 0.75%Ce-0.4%La-TiO2 sample was the highest,reaching 89.4%.