A new method of preparation of AgBr/TiO 2 composites and investigation of their photocatalytic activity
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RESEARCH PAPER
A new method of preparation of AgBr/TiO2 composites and investigation of their photocatalytic activity Yangyang Xing • Rui Li • Qiuye Li • Jianjun Yang
Received: 22 March 2012 / Accepted: 2 November 2012 / Published online: 9 November 2012 Ó Springer Science+Business Media Dordrecht 2012
Abstract Silver bromide/titanium dioxide composites were first prepared using titanic acid nanobelts (TAN) as the TiO2 source. First, TAN reacted with AgNO3 to prepare Ag-incorporated TAN by the ionexchange method, and then AgBr/TAN was obtained after adding NaBr. Finally, AgBr/TAN was transformed to AgBr/TiO2 composites by calcination. The post-treated calcination would not only convert TAN to TiO2 (H2Ti2O4(OH)2 ? 2H2O ? 2TiO2), but also increase the effective contact between AgBr and TiO2, further to improve the separation of photo-generated electron-holes. The advantage of this preparation method is the small particle size (ca. 10–20 nm) and well dispersion of AgBr on the surface of TiO2, and close contact between AgBr and TiO2. The effect of the different calcination temperature on the morphology, structure, and properties of AgBr/TiO2 composites was investigated in detail. The AgBr/TiO2 composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and ultraviolet–visible diffuse reflectance spectra (UV– Vis DRS). Comparing with pure TAN, AgBr, and AgBr/P25 mixture, the AgBr/TiO2 composites exhibited enhanced photocatalytic activity in decomposition of methyl orange (MO) under visible light irradiation. Y. Xing R. Li Q. Li (&) J. Yang Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004, China e-mail: [email protected]
Keywords AgBr/TiO2 nanocomposites Titanic acid nanobelts Photocatalysis Visible light
Introduction Titanium dioxide has been investigated intensively in utilization of solar energy for environmental purification, including the decomposition of toxic and hazardous organic pollutants in contaminated air and water (Hoffmann et al. 1995; Wang et al. 2011; Park et al. 2006). However, the main drawbacks of TiO2 are low quantum yields and the lack of visible light utilization because of the large band gap. Therefore, it is of great interest to improve the visible lightresponded photocatalytic activity of TiO2 to widen its practical applications. Up to now, numerous methods have been applied to solve these problems, such as doping with metals (Dvoranova et al. 2002) or nonmetal elements (Li et al. 2011), coupling with the secondary semiconductors (Chen et al. 2011), and photosensitization (Li and Lu 2007). Recently, silver halides became a hot topic in photocatalysis because of their strong visible light absorption and high photocatalytic activity. Wang et al. (2009, 2010, 2010) reported that Ag/AgCl, Ag/AgBr, and Ag@Ag (Br,I) can significantly enhance the visible light photocatalytic activity for degradation of methyl orange and photoreduction of
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heavy metal (hexavalent chromium). Sun and colleagues fou
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