Preparationand Photocatalytic Performance Of Modified Titanium Dioxide

TiO2materials have many excellent properties, which are widely used in the photocatalysis,bionic of medicine, dye-sensitized solar cells and many other fields. However, the wide band gap of TiO2reduces its utilization of photons. Therefore, the research on TiO2nanomaterial modification has attractedmuch attention.In the recent references, there are many methods for modifying TiO2, such as precious metaldeposition, ion doping, compound semiconductors and photosensitizing dyes. In recent years, thesynthesises of TiO2nanocrystalline with special structures and special carbon material composite structureshave become a hot research at home and abroad. Due to the special structure of TiO2material, it possessesmore advantages, such as rich mesopores and large specific surface area. Therefore, TiO2has been used asa useful candidate for various applications in the fields of biomedicine, photocatalysis and dye-sensitizedsolar cells.In this thesis, there are several major works as follows:(1) Hierarchical anatase TiO2spheres were successfully prepared via a simple solvothermalmethod by using titanium n-butoxide and acetic acid as raw material. Scanning electron microscope (SEM),X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR) were used to characterize theprecursor and products. The main influence factors during the preparation of TiO2spheres wereinvestigated, such as the addition of reactants, reaction time, reaction temperature, calcination temperatureand so on. The photocatalytic activity of the TiO2microspheres was evaluated by the degradation ofreactive brilliant blue KN-R solution under ultraviolet light. The results demonstrated that the hierarchicalstructures were assembled from numerous highly crystallized anatase nanocrystals, and the particlediameter was2-4μm. The TiO2spheric material exhibited good photocatalytic activity. The degradationrate of reactive brilliant blue KN-R was about97.79%after60min irradiation by ultraviolet light, while itwas1.41times higher to commercial P25.(2) Core-shell anatase TiO2spheres were successfully prepared via a simple solvothermalmethod by using titanium n-butoxide as raw material, without adding structure inducer and template. In thesolvothermal process, the oxygen bubbles were produced by the decomposition of Ti(O2)2+, which could act as soft templates for the formation of core-shell-structured TiO2materials. SEM, XRD and UV-vis DRSwere used to characterize the precursor and products. Infuencing factors in the preparation of TiO2wereinvestigated. The photocatalytic activity of the TiO2microspheres was evaluated by degradation methyleneblue solution under ultraviolet light. The results showed that the TiO2particle diameter was2-3μm, and thecrystallinity were very good. Under the same conditions, core-shell anatase TiO2spheres exhibited higherphotocatalytic properties compared with commercial Degussa P25powder, which degradation rate was2.18times higher to commercial P25.(3) First, the ordinary TiO2nanoparticles were synthesized by solvothermal method. C3N4/TiO2materials with different mass ratios were composited by graphite-like C3N4and TiO2nanoparticles viaphysical mixing by using methanol as solvent. SEM, XRD and UV-vis DRS were used to characterize theproducts. The optimum quality ratio of C3N4and TiO2was investigated. The photocatalytic activities wereevaluated by degradating the orange Ⅳ under the UV light and visible light irradiation. The results showedthat all the C3N4/TiO2photocatalysts exhibited higher photocatalytic activity than the pure TiO2sampleunder UV light irradiation. The photocatalytic activity was enhanced gradually with the increasingproportion of C3N4, the optimum synergetic effect of C3N4/TiO2was found at a weight ratio of5%.The experimental results showed that the modified TiO2materials had better photocatalyticperformance. It provides reference for the synthesis of new TiO2materials with high photocatalytic activityin future. Moreover, the simple preparation process and low cost made it possible to apply in industry.