甘油中水合TiO2及不同晶型纳米TiO2光致变色现象

系统地研究了甘油中水合TiO₂及不同晶型纳米TiO₂的光致变色现象。实验结果显示无定型水合TiO₂具有最明显的变色行为,锐钛型纳米TiO₂变色程度次之,金红石型纳米TiO2没有明显变色现象发生,混晶型(金红石和锐钛)纳米TiO₂的变色程度介于金红石型和锐钛型之间。XPS结果表明TiO₂的光致变色是由Ti³⁺引起的。从电子-空穴对复合率影响Ti ³⁺形成的角度对实验现象作出了详细解释,电子-空穴对复合率越高,Ti³⁺形成率越低,从而变色程度越浅;并运用双注入机制和小极子模型阐述了不同晶型TiO₂的光致变色机理。分析了甘油环境对TiO₂光致变色现象的影响,得出甘油对TiO₂的光致变色行为有促进作用。

Photochromic property of hydrous TiO2 and different crystalline nano-TiO2 in glycerol

The photochromic of nano-TiO₂ with different crystals and the hydrous TiO₂ in the glycerol environment were systematic studied in this paper. Experimental results showed that,amorphous TiO₂（hydrous TiO₂）has the most obvious discoloration,while rutile nano-TiO₂ has no obvious coloration,the degree of discoloration of anatase nano-TiO₂ is between rutile and amorphous,the mixed crystals（rutile and anatase）nano-TiO₂ is weaker than anatase but stronger than rutile. The samples were characterized by X-ray photoelectron spectroscopy（XPS）and UV-visible（UV-vis）,and the results indicated that the Ti³⁺ existed in the colored sample and the visible absorption spectrum of samples were significantly different before and after colored. The double-injection mechanism and the small polaron model were used to describe the photochromic mechanism of TiO₂. The electron-hole recombination rate effected on the Ti³⁺ formation and the effects of glycerin for TiO₂ photochromic phenomenon were investigated in this paper. The formation rate of Ti³⁺ decreased with the increasing of the electron-hole recombination rate,which leaded to the weakening of the color. The glycerin could promote the photochromic of TiO₂..