掺杂二氧化锡的二氧化钛的光学性质及其光催化特性

二氧化钛多相催化是一种极具前途的环境污染深度净化技术。 本文以钛酸四丁酯和四氯化锡为原料，无水乙醇为溶剂，采用溶胶-凝胶法制备了掺杂二氧化锡的二氧化钛薄膜和复合氧化物粉体。通过测量薄膜的吸收光谱推算光学能隙，结果发现掺杂样品的光学能隙比纯二氧化钛样品有所变小。随着热处理温度的提高，掺杂和纯二氧化钛样品的光学能隙都略微降低。X-射线衍射分析表明，复合氧化物粉体的热处理温度对样品的晶体结构和光催化性能有重要影响。以掺杂二氧化锡5 % 摩尔比的样品与纯二氧化钛对照，500 ℃以下热处理样品以锐钛矿结构为主，600 ℃热处理样品为锐钛矿与金红石相共存，并显示了较好的光催化性能。透射电子显微镜观察显示，同样600 ℃热处理，掺杂样品要比纯二氧化钛具有更小的颗粒尺寸。在700 ℃热处理的样品中，掺杂样品只存在金红石相而纯二氧化钛样品中仍存有锐钛矿相。用阿伦尼乌斯经验关系式推测的晶粒生长的活化能,纯二氧化钛47.486 kJ.mol, 掺杂5 % 摩尔比的复合氧化物样品33.103 kJ.mol。以亚甲基蓝为降解物质，考察了掺杂量和热处理温度对样品的光催化性能。

Optical Absorption Property and Photo‐catalytic Activity of Tin Dioxide‐doped Titanium Dioxides

SnO₂‐doped TiO₂ films and composite oxide powders have been prepared by a sol‐gel method. Ti(OC₄H₉)₄ and SnCl₄·5H₂O were used as precursors and C₂H₅OH was used as solvent. The optical absorption measurements indicate that the composite oxide SnO₂‐TiO₂ thin films exhibit smaller optical energy band gaps than pure TiO₂ thin films and the optical energy band gap decreases as calcining temperature increases. X‐ray diffraction was used to characterize the phase transition for the composite oxide powders at different calcining temperatures. Aanatase phase is the main crystal structure in both pure TiO₂ and Sn_0.05Ti_0.95O₂samples if calcining temperature is below 500 °C. The rutile phase has appeared and coexisted with the anatase crystal phase for both pure TiO₂ and Sn_0.05Ti_0.95O₂ composite oxides when calcining was at 600 °C. Transmission electron microscopy analysis shows a smaller grain size in Sn_0.05Ti_0.95O₂ powders than TiO₂ powders calcined at 600 °C. When calcining temperature is 700 °C, there is only rutile phase in Sn_0.05Ti_0.95O₂ samples, but there are still two crystal phases, anatase and rutile, coexisting in the pure TiO₂ samples. Assuming the grain growth obeys the first order kinetics, Arrhenius empirical relation has been used to estimate the activation energy of 47.486 and 33.103 kJ·mol^?1 for the grain growth of TiO₂ and Sn_0.05Ti_0.95O₂, respectively. The photo‐catalytic activity of the powder samples has been examined by measuring the degradation of methylene blue solution under ultra‐violet irradiation. Two effective factors of photo‐catalytic activity namely, the content of SnO₂ in the TiO₂ samples and the calcining temperature, have been optimized based on the photo‐catalytic degradation of methylene blue solution.