扩散火焰法制备TiO2纳米晶及其光催化活性

利用自行设计开发的扩散火焰燃烧反应器,以四氯化钛为前驱体,通过四氯化钛气相水解法,改变四氯化钛进料速率和中心环氧气含量,合成粒径和晶型组成可控的二氧化钛纳米晶。透射电镜(TEM)和X射线衍射仪(XRD)分析结果表明:制备的球形样品分散性好、粒径分布均匀、晶化完整。以罗丹明B染料在紫外光条件下的降解为模型反应,考察了球形二氧化钛纳米晶的粒径和晶型组成与光催化活性的关系。结果表明:晶型组成不变时,晶粒尺寸越小,光催化活性越好;而当晶粒尺寸不变时,随着锐钛矿型质量分数的增加,光催化降解罗丹明B的活性先增加后降低,锐钛矿型二氧化钛质量分数为0.80时,光催化活性最好。

Preparation of TiO2 Nanocrystallite by co-Flow Diffusion Flames and Their Photocatalytic Activity

TiO_2 nanocrystallite was synthesized by gas hydrolysis of titanium tetrachloride conducted in co-flow diffusion flames.TiCl_4 feed rate and O_2 mole fraction in the center tube were varied to tune the grain size and the anatase content of TiO_2 nanocrystallite.Transmission electron microscopy(TEM) and X-ray powder diffraction(XRD) results show that the nanocrystallite is spherical in shape,uniformly distributed within the narrow size range. The photocatalyst activity of TiO_2 nanocrystallites under UV(irradiation) is evaluated using RhB as a mode organic compound.The results indicate that when the anatase content of TiO_2 nanocrystallite is constant,the grain size is in the range of 9.4 nm to 15.5 nm,smaller size has higher photocatalytic activity;when the grain size is constant,with the increasing of the anatase content,the photocatalytic activity increases first and then decreases.The anatase content of 0.80 has the highest photocatalytic activity for RhB degradation.