溶胶-凝胶法制备不同晶相组成TiO_2及其可见光催化活性

采用溶胶-凝胶法制备了不同晶型的TiO2纳米粒子,以X-射线衍射、扫描电镜、红外光谱和紫外-可见固体漫反射吸收光谱对其进行了表征及光吸收特性研究,以可见光下TiO2对罗丹明B的降解率评价其光催化活性.结果表明TiO2纳米粒子的晶相分别为锐钛矿纯相、锐钛矿/金红石混晶和金红石纯相,粒子的平均粒径为10 nm左右,许多纳米粒子聚集形成较大的颗粒,且表面含有活性羟基.制备的三种晶相组成的TiO2对罗丹明B均具有较高的可见光催化活性,活性均高于商品TiO2（P25）,且活性按锐钛矿纯相、混晶和金红石纯相的顺序依次降低,可见TiO2的可见光催化活性与其晶相组成密切相关.

Preparation of TiO_2 with various phase compositions by sol-gel method and their photocatalytic activities in visible light

In the present paper TiO2 nanoparticles with various crystal phases were synthesized by sol-gel method and characterized by XRD,SEM and IR spectra,respectively.Their optical properties were investigated by UV-Vis diffuse reflection spectra and the photocatalytic activities were assessed by the photodegradation of rhodamine B in visible light.The results show that the TiO2 nanoparticles are pure anatase,anatase/rutile mixed phases and pure rutile,respectively.Their calculated average particle size is around 10 nm and these small particles agglomerated into big conglomerations with active hydroxyls on their surfaces.Their photocatalytic activities on rhodamine B in visible light were all higher than that of the commercial TiO2（P25）,and the activities decreased in the sequence of pure antatase,mixed crystal phases and pure rutile,which clearly shows that the photocatalytic activities of TiO2 nanoparticles are closely related with their crystal phase compositions.