| Titanium dioxide has extremely extensive application in various field such as photocatalyst, antibacterial materials and hydrophilic materials.In recent years, the application of titanium dioxide in solar cells has attracted much attention from the researchers. Because titanium dioxide has special physical and chemical properties, such as good electronic transmission characteristics, it plays an important role in dye sensitization solar cells and perovskite solar cells.Solar cells had attracted much more attention as the clean energy because of the energy crisis, which result that the research of titanium dioxide has become a research hotspot. The size and shape have a great impact on the performance of titanium dioxide. So the preparation of size-controlled titanium dioxide is extremely important. In this paper, the titanium dioxide nanoparticles with controllable size and shape were prepared by the liquid phase method which is easy to control the size and shape of the materialsThrough adjusting the reaction parameters, such as reaction temperature, duration, and concentration of the reactants, the size, shape, and dispersibility of the products can be controlled. The adding of surfactant is the effective way to control the size and shape of titanium dioxide. In this paper, a series of experiments were carried out to study the size and shape of titanium dioxide by solvothermal method and titanium sulfate was mainly used as raw materials. The size, shape, structure and morphology of titanium dioxide are characterized by XRD, SEM, TEM and DLS. Meanwhile, the spectroscopic properties were characterized by FT-IR. The main work and the results of this paper are as follows:(I) TiO2 particles in micron were prepared by the hydrothermal method with titanium sulfate as the titanium source and urea as a precipitating agent. The reaction temperature, reaction time and Ti(SO4)2 solution concentration changes change the solubility of Ti(SO4)2 in hydrothermal reaction system. TiO2 particle with smaller average size were prepared at higher solution solubility conditions and low solvent content. The orthogonal experiment was used to discuss the impact of experimental parameters on the titanium dioxide particle size.The result shows that the reaction temperature, titanium sulfate concentration have larger impact on the particle diameter, and the impact of reaction time and molar ratio of Ti(SO4)2/urea is relatively small. The Ti(SO4)2 reaction rate and the introduce of steric hindrance were controlled to a certain extent by controlling the molar ratio of Ti(SO4)2/urea.TiO2 prepared in series of experiments are nearly spherical micron sized particles. Particles are micron/ nanometer particles mixed. It showed the existing of Osworld ripening phenomenon in the synthetic process, the size distribution chaos of TiO2 particles and serious aggregation.(2) Using Titanium sulfate as the titanium source, urea as precipitator and water/ethanol mixed solvent to prepare nano TiO2 by solvothermal method. The effects of different experimental parameters on the particle size of TiO2 particles were discussed. The addition of ethanol can improve the dispersion of TiO2 nano powder and decrease the aggregation of CTAB in a certain extent. The addition of cationic surfactant can effectively improve the aggregation problem.70nm TiO2 nanoparticles with good dispersibility were obtained at 180℃ for 6h when the concentration of Ti (SO4)2 solution is 0.05mol/L molar, ratio of Ti (SO4)2/urea is 1:2, volume ratio of water/ethanol is 1:4 and add a certain amount of CTAB.(3)In this experiment, monodisperse and well crystallized TiO2 nanoparticles were prepared by solvothermal method. Titanium sulfate was used as titanium source, oleic acid and oleylamine were used as surfactant. By changing the precursor concentration, reaction time and the volume ratio of OA/OM, it can be ensured that the size of anatase TiO2 particles can be continuously adjusted between 4-40nm. According to the TEM, XRD, DLS and FT-1R detection, reaction mechanism of preparing monodisperse and highly crystalline TiO2 nanoparticles by hydrothermal method in the OA/OM system was explored.In this mixed system, we proposed that hydrolysis of titanium sulfate, ammonolysis reaction of OA and OM and hydrolysis of amide in this system interact and restrict each other. Relatively stable system can be obtained by adjusting parameters, it can be the guarantee of stable existence of monodisperse and highly crystalline TiO2 nanoparticles.The main features and innovations of this paper are embodied in:The reaction mechanism of solvothermal synthesis of nano TiO2 was studied by using titanium sulfate OM and OA. In a certain range, the particle size can be continuously controlled by the adjustment of the experimental parameters. |
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