原位合成可见光响应TiO_2/SnS_2及其光催化还原水中Cr(Ⅵ)的性质研究

In-situ One-step Solvothermal Synthesis of TiO_2 Nanocrystals-covered SnS_2 Nanoplates with High Performance for Photocatalytic Reduction of Aqueous Cr(Ⅵ)

本文以钛酸四丁酯、四氯化锡和硫代乙酰胺为原料,在无水乙醇-水-冰醋酸的混合溶剂中得到可见光响应TiO_2/SnS_2纳米复合材料,采用XRD、TEM、HRTEM、XPS和UV-vis等测试手段表征了产品的结构、组成和光学性质;以可见光(λ>420 nm)为光源、K2Cr2O7水溶液为模型污染物,考察了所制产品和物理混合法所制的具有相同组成的PM-TiO_2/SnS_2的光催化活性.实验结果表明:得到了可见光响应的表面分散型TiO_2/SnS_2纳米复合材料具有比SnS_2纳米片、TiO_2纳米晶和PM-TiO_2/SnS_2纳米粉更高的可见光催化活性和良好的光催化稳定性;TiO_2和SnS_2具有匹配的能带结构,形成的表面分散型的异质结界面利于光生载流子有效分离和转移是ISTiO_2/SnS_2具有良好催化性能的重要因素.

TiO_2 nanocrystals-covered SnS_2 nanoplates were synthesized via a simple and cost-effective insitu one-step solvothermal method, using Sn Cl4·5H_2O, thioacetamide and tetrabutyl titanate as the reactants and ethanol-water-acetic acid solution as the solvent. The compositions, structures and optical properties of the as-synthesized TiO_2/SnS_2 composites were characterized by X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectra. It was observed that the as-synthesized TiO_2/SnS_2nano-heterojunctions not only demonstrated much higher efficiency than SnS_2 nanoplates, TiO_2 nanocrystals and physical mixture of SnS_2 nanoplates and TiO_2 nanocrystals in photocatalytic reduction of aqueous Cr（VI） under visible light（λ 420 nm） irradiation, but also had high photocatalytic stability. The greatly improved photocatalytic performance of the as-synthesized IS-TiO_2/SnS_2nano-heterojunctions was mainly attributed to the efficient charge transfer and separation at the heterojunction interfaces between closely contacted SnS_2 nanoplates and TiO_2 nanocrystals, as well as the matching band potentials of SnS_2 and TiO_2.