溶剂热法制备Ag/TiO2纳米材料及其光催化性能

以乙醇为溶剂, 钛酸四丁酯为前驱体, 用溶剂热法制备了Ag表面修饰的负载型纳米二氧化钛光催化剂. 利用X射线衍射(XRD)、N₂吸附-脱附(BET)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱等技术对其进行了系统的表征, 以亚甲基蓝(MB)溶液的脱色降解为模型反应, 考察了不同Ag含量样品的光催化性能. 结果表明: 用溶剂热法制备的样品中TiO₂皆为锐钛矿相, 金属Ag颗粒沉积在TiO₂表面, 粒径为2 nm左右, 比表面积较溶胶凝胶法制备的样品大大增加, 最高可达151.44 m²·g^-1; UV-Vis光谱和光催化实验表明: Ag修饰使TiO₂对光的吸收能力大大增强, 吸收带边红移至可见光区, 亚甲基蓝在该复合材料上的光催化降解反应遵循一级反应动力学模型; 溶剂热法制备样品的光催化性能明显好于溶胶凝胶法制备的样品, 在紫外光和可见光下, Ag摩尔分数为5%的样品表现出最佳的光催化活性.

Solvothermal Preparation of Ag/TiO2 Nanoparticles and Their Photocatalytic Activity

Visible-light photoactive Ag/TiO2 catalysts were successfully prepared by a solvothermal method. The samples were characterized by X-ray diffraction (XRD), N₂ adsorption-desorption isotherm (BET), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible (UV-Vis) spectroscopy. The photodegradation of methylene blue (MB) solution was used to evaluate the photocatalytic activity of the catalyst under UV and visible light irradiation (λ>400 nm). XRD results showed that the TiO₂ was in the pure anatase phase. Ag nanoparticles were loaded onto the TiO₂ nanoparticle surface and this had little influence on the crystal phase and the particle size of TiO₂. The specific surface area of the samples was far higher than that for the samples prepared by the sol-gel method and the sample with Ag molar fraction of 5% had the highest value of 151.44 m²·g^-1. The absorption spectrum of the Ag-modified TiO₂ increased greatly and the adsorption edge was extended into the visible region. The photodegradation of MB solution followed a pseudo-first-order kinetic expression. The photocatalytic activities of the Ag/TiO₂ composites prepared by the solvothermal method were remarkably higher than those prepared by the sol-gel method. Under UV or visible light irradiation, the optimal photoactivity was obtained for the sample with a Ag molar fraction of 5%.