采用Sol-gel法制备SiO_2/TiO_2光催化双层薄膜

Preparation of Photocatalytic Double Films of SiO_2 and TiO_2 by Sol-gel Method

采用溶胶-凝胶(sol-gel)旋涂法在玻璃基体上制备SiO_2/TiO_2双层膜,提高TiO_2的光催化性并赋予传统玻璃自洁净功能。通过增加SiO_2阻挡层,防止玻璃中的碱金属离子向TiO_2层的扩散,同时以多孔SiO_2为模版,增加TiO_2的比表面积,提高光的利用率,进而提高其光催化活性。对各影响因素进行了研究,得出最佳制备工艺条件。并采用降解甲基橙溶液的方法对其光催化性能进行评价,采用紫外-可见分光光度计对镀膜样品的透射比及吸光度进行测试;采用XRD对薄膜的结构进行分析。实验结果表明:SiO_2溶胶陈化时间为4 d,调节溶胶p H值为5,母液与阶梯醇的质量比为3∶1,旋涂速度为3000 r/min,加液量为3滴,400℃热处理保温3 min时,制备出的薄膜在可见光范围内的平均透射比可达到94.5%,比未镀膜玻璃基片提高约3.2%,具有最大透射比。400℃热处理6 min的双层膜的光催化性能最好,在紫外灯的照射下对甲基橙溶液的降解率相较于单层二氧化钛光催化薄膜明显提高,提高了25.6%。

In this paper, SiO2/TiO2 double films were prepared by sol-gel process on the glass substrate with spin coating technology to improve the photocatalytic activity of TiO2 and give conventional glass self- cleaning function. SiO2 barrier layer can prevent the alkali metal ion in glass diffusioning to the TiO2 layer, increasing the specific surface area of TiO2 using the antireflection of SiO2 improves the utilization rate of light and increases its photocatalytic activity. By researching on the factors of sol aging time, the ratio of mother liquor and diluent, coating speed, heat treatment temperature, holding time, the ratio of hydrophobic agent and curing temperature, we obtained a set of optimum preparation conditions. The photocatalytic activity was evaluated by the degradation rate of methyl orange solution. The optical transmittance of films was studied by UV-Vis spectrophotometer. And the structures of the films were characterized by XRD. The experimental results show that the films have the best optical performance with average transmittance 94.5% in the visible wavelength range which increases about 3.2% than that of the uncoated substrate in the optimum condition of 4 d sol aging time, pH value 5 of the sol adjusted by acetic acid, the mass ratio of mother liquor and diluent 3： 1. coating sneed 3000 r/min with 3 drops of the solution, 400 ℃ of the heating treatment temperature and 3 min of the holding time. Heated at 400 ℃ and held for 3 min, the films have the best photocatalytic activity. Under the irradiation of UV light, the degradation rate of this sample for methyl orange solution is higher than monolayer TiO2 light catalytic film by 25.6%.