Preparation Of Ti O₂/mica Thin Film And Study Of Its Optical Properties

Since the discovery of the photocatalytic properties of TiO₂ semiconductor materials,researchers have continued to deepen their research on TiO₂ multifunctional materials.Researchers have carried out a lot of experimental and theoretical research work in order to improve the application efficiency of TiO₂.In this study,we used electron-beam evaporation to prepare TiO₂ thin films on silicon substrates under high vacuum conditions,and studied the effects of different environments on the microstructure and optical properties of the TiO₂ thin films,as well as the photocatalytic efficiency.According to the X-ray diffraction pattern,the sample presents an anatase phase and has good crystallinity.At the same time,we can also see that the oxygen annealing atmosphere is conducive to the reduction of the impurity phase Ti₂O₃.Scanning electron microscopy images show that the surface of the TiO₂ film is composed of uniform and dense spherical nanoparticles.In addition,we found through X-ray diffraction patterns that the crystallinity of samples annealed in oxygen atmosphere is higher than that of samples annealed in air and nitrogen atmosphere.The band gap energy of the oxygen annealing sample obtained from the experiment is 2.98 e V.The photocatalytic degradation experiments show that the degradation rates of the samples annealed in air,nitrogen and oxygen atmosphere are 1.6%,4.6%and 4.8%,respectively.It can be said that the annealing atmosphere has a significant effect on the degradation rate of the samples prepared by electron-beam evaporation in methylene blue solution.At an annealing temperature of 550°C,an oxygen atmosphere is an appropriate annealing environment to improve the photocatalytic efficiency of the TiO₂ film.The results of the experiment show that as the annealing temperature increases,the sample particles become significantly larger.The samples annealed with air and N₂ showed impurity peaks.With the increase of annealing temperature and O₂ annealing conditions,the impurity peak intensity gradually decreased.The crystallinity of samples annealed in the same atmosphere is optimized with the increase of annealing temperature.In short,it is preferable to obtain samples with lower band gap energy at these annealing temperatures,and the annealing atmosphere is preferably an air atmosphere.In these annealing atmospheres,samples with lower band gap energy are preferably obtained at an annealing temperature of 750°C.In this study,we studied the effect of annealing temperature on the surface morphology,crystal structure and optical properties of the TiO₂/mica film and the effect of stress on the photocatalytic efficiency.The research results show that as the annealing temperature increases,the grain size becomes larger and the band gap energy of the film becomes smaller.We also did experiments on photocatalytic degradation of TiO₂/mica film under the influence of pressure and under natural conditions at the same time.The experimental results are:without affected by the pressure,the degradation rates of the annealed films at 600℃,650℃,and 700℃are 8.56%,5.78%and 2.39%respectively;after affected by pressure,the degradation rates of the annealed films at 600℃,650℃,and 700℃are 8.79%,6.89%and 3.28%,respectively.The experimental results show that the degradation rate of samples affected by pressure is greater than the degradation rate of samples in the natural state,and the degradation rate of samples affected by pressure at the annealing temperature of 650℃is greater than that of samples affected by the external forces at 600℃and 700℃.The degree of improvement indicates that the stress has a certain promoting effect on the improvement of the photocatalytic degradation rate of the film.