Sn离子促进纳米TiO_2颗粒低温制备及机理分析

Low Temperature Preparation and Mechanism of Nano-TiO_2 Hastened by Sn Ions

分别以Sn4+和Sn2+为促进剂,钛酸丁酯为主要原料,在80℃下通过强迫水解法制备了纳米TiO2颗粒。利用X射线粉末衍射(XRD)、拉曼光谱(Raman)、透射电镜(TEM)和紫外-可见漫反射光谱(DRS)对产物进行表征。考察了不同酸度下Sn4+和Sn2+对TiO2晶化过程的影响,结果表明:引入Sn4+后,在合适的酸度条件下回流50 min后即可获得锐钛矿结构TiO2,TEM观察表明其晶粒粒径约为5 nm左右。紫外-可见漫反射谱分析表明:加入Sn4+或Sn2+所制备的两种粒子,其吸收带边同体相材料相比向短波方向移动。机理分析认为产物的结构主要取决于水解时的酸度,Sn离子主要起到降低成核表面能垒、促进晶核形成的作用。

Nano-TiO2 was prepared by forced hydrolysis method at 80 ℃ using Ti（OBu）4 as raw material and Sn4＋or Sn2＋as accelerating agent.The as prepared samples were characterized by XRD,Raman spectrum,TEM and DRS.The effects of Sn4＋or Sn2＋under different acidity on the crystallization of nano-TiO2 were studied.The results show that TiO2 of anatase type can be synthesized within 50 min of distillation time with the addition of Sn^4＋under the proper acidity,and observation form TEM images show that the size of nano-TiO2 particle was about 5 nm.The results of UV-Vis diffuse reflection spectra indicate that compared with the bulk TiO2,the absorbance band edge of as-prepared samples with the addition of Sn^4＋ and Sn^2＋ was shifted to short wave.The analysis of mechanism indicate that the crystal form of TiO2 was mainly determined by the acidity,and the addition of Sn ions accelerated the formation of TiO2 by reducing the nucleation surface energy barrier.