Photocatalytic Reduction of Cr(VI) in an Aqueous Suspension of Surface-Fluorinated Anatase TiO sub(2) Nanosheets with Exposed {001} Facets

• Published in: Industrial & engineering chemistry research Vol. 52; no. 28; pp. 9556 - 9565-9556-9565
• Main Authors: He, Zhiqiao, Cai, Qiaolan, Wu, Ming, Shi, Yuanqiao, Fang, Huiying, Li, Lingdan, Chen, Jiancheng, Chen, Jianmeng, Song, Shuang
• Format: Journal Article
• Language: English
• Published: 17.07.2013
• Subjects: Dissolution; Exposure; Fluorination; Nanostructure; Photocatalysis; Reduction; Surface chemistry; Titanium dioxide
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie400812m

In the present work, reduction of Cr(VI) induced by UV-visible light in aqueous solution was investigated. The aqueous medium contained TiO sub(2) nanosheets and no additional reducing agents or hole scavengers. A hydrothermal method was used to synthesize fluorinated TiO sub(2) nanostructures with various percentages of exposed {001} facets and initial F/Ti ratios. Fluorine-free TiO sub(2) nanosheets were obtained by washing the TiO sub(2) samples with NaOH solution. The surface fluorination facilitates the adsorption process by increasing the number of surface OH groups generated. Moreover, fluorination efficiently inhibits the recombination of photogenerated electron-hole pairs. The {001} facets have an indirect role in the photocatalytic reduction of Cr(VI) because oxidative dissolution of H sub(2)O occurring on {001} facets and Cr(VI) reduction occurring on {101} facets are simultaneous reactions. The optimal ratio of exposed {001} to {101} was found to be 72:18.