Surface fluorination of single-phase TiO₂ by thermal shock method for enhanced UV and visible light induced photocatalytic activity

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• 作者：Tien Khoa Le ; Delphine Flahaut ; Herv¨¦ Martinez ; Thierry Pigot ; Huu Khanh Hung Nguyen ; Thi Kieu Xuan Huynh
• 关键词：Fluorination ; Monophasic TiO2 ; Thermal shock ; Adsorption behaviour ; Photocatalytic activity
• 刊名：Applied Catalysis B: Environmental
• 出版年：2014
• 出版时间：January, 2014
• 年：2014
• 卷：144
• 期：Complete
• 页码：1-11
• 全文大小：2087 K

文摘

Fluorinated TiO₂ was prepared from anatase and rutile monophasic TiO₂ nanopowders by thermal shock method at different temperatures (400-950 ¡ãC), then characterized by XRD, SEM, XPS in order to elucidate the influences of thermal shock fluorination on the crystallite structure, morphologies and surface structure of TiO₂ in different phases. Their photocatalytic activities were evaluated via the degradation of methylene blue. According to the results, the fluorination below 600 ¡ãC did not change the crystallite structure or the particle size. However, the surface hydroxyl groups content is increased with the creation of fluoride ions and oxygen/titanium vacancies on the surface of anatase/rutile TiO₂ which are all involved in the improvement of the photocatalytic activity. The TiO₂ anatase fluorinated at 500 ¡ãC showed the best photocatalytic behaviour under UV light whereas the TiO₂ rutile fluorinated at 500 ¡ãC is the best photocatalyst under visible light. At higher thermal shock temperatures, the photocatalytic activity decreased, which was assigned to the decrease of the surface hydroxyl groups and vacancies content and the formation of the K₂Ti₆O₁₃ phase.