Chemically Binding Carboxylic Acids onto TiO2 Nanoparticles with Adjustable Coverage by Solvothermal Strategy

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• 作者：Qiyun Qu ; Hongwei Geng ; Ruixiang Peng ; Qi Cui ; Xiaohong Gu ; Fanqing Li ; Mingtai Wang
• 刊名：Langmuir
• 出版年：2010
• 出版时间：June 15, 2010
• 年：2010
• 卷：26
• 期：12
• 页码：9539-9546
• 全文大小：980K
• 年卷期：v.26,no.12(June 15, 2010)
• ISSN：1520-5827

文摘

This paper presents a solvothermal strategy for chemical modification of TiO₂ nanoparticles with carboxylic acids. Solvothermal reaction between the TiO₂ nanoparticles and carboxylic acid molecules in an autoclave at 100 °C provides carboxylic acid-modified TiO₂ particles with a modification efficiency much higher than the conventional immersion method. TiO₂ nanoparticles were prepared by hydrolysis of titanium isopropoxide in nitric acid solution; the modified nanoparticles were characterized by powder X-ray diffraction pattern, scanning electron microscopy, absorption and Fourier transform infrared spectra, and thermogravimetric analysis. Results show that the binding form of the modifier molecules on TiO₂ surface is in a bidentate chelating mode, the crystalline phase composition and morphological structure of the preformed TiO₂ nanoparticles are not affected by the solvothermal reaction, and the surface coverage of the modifier molecules can be adjusted by the weight ratio of modifer/TiO₂ during feeding. It is evident that the reaction processes in the solvothermal strategy involve the formation of double hydrogen bondings between carboxylic acid molecule and TiO₂ at the same Ti site and the coordination at solvothermal temperature by dehydration from the hydrogen bondings. The solvothermal strategy for modifying TiO₂ nanoparticles is expected to find potential applications in many fields; for example, our results demonstrate that the photovoltaic performance of the TiO₂ nanoparticles can be improved by the solvothermal modification even with an insulating modifier and controlled by the modifier coverage.