Effect of Au supported TiO₂ with dominant exposed {0 0 1} facets on the visible-light photocatalytic activity

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• 作者：Shuying Zhu ; Shijing Liang ; Quan Gu ; Liyan Xie ; Jixin Wang ; Zhengxin Ding ; Ping Liu ; ^{liuping@fzu.edu.cn}
• 关键词：TiO2 nanosheets ; Au nanoparticles ; {0  ; 0  ; 1} facets ; Plasmonic photocatalyst ; Visible light
• 刊名：Applied Catalysis B ; Environmental
• 出版年：2012
• 期刊代码：4_09263373
• 类别：ce
• 出版时间：30 May, 2012
• 卷：119-120
• 期：Complete
• 页码：146-155
• 文件大小：1715 K

摘要

Novel visible-light-driven plasmonic photocatalyst Au/TiO₂ nanosheets with a high percentage of exposed {0 0 1} facets were fabricated by hydrothermal treatment of tetrabutyl titanate and hydrofluoric acid, followed by the polyol reduction process (denoted by Au/TiO₂-0 0 1). The prepared samples were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N₂-sorption, UV-vis diffuse reflectance spectroscopy, and photoluminescence spectra. The variations of photoelectric response after depositing Au nanoparticles (NPs) on TiO₂-0 0 1 nanosheets were investigated by the photoelectrochemical experiment. The results display that the Au NPs with average diameter of ca. 5 nm were deposited on (0 0 1) facet of TiO₂ nanosheets in the form of metallic state. The samples exhibited a strong absorption in the visible light region due to the surface plasmon resonance (SPR) effect of Au NPs. For the photocatalytic degradation of rhodamine B (RhB) in aqueous solution, the Au/TiO₂-0 0 1 showed superior photocatalytic activities compared with bare TiO₂-0 0 1 and other Au deposited photocatalysts, such as Au/P25 (Degussa TiO₂), Au/anatase TiO₂, and Au/rutile TiO₂. The enhanced photocatalytic activities can be explained by its unique morphology, larger surface area, and smaller crystallite. Meanwhile, TiO₂ dominated {0 0 1} facets with higher electron mobility and better adsorption of pollutant molecule may be another reason for the higher photocatalytic activity. In addition, the Au NPs are believed to play an essential role in enhancing the photoreactivity because they are able to generate photoelectrons and enhance the visible light absorption intensity. The effects of the Au content, the calcination temperature of TiO₂-0 0 1, the supporter, and the reaction atmosphere on photocatalytic activities were investigated in detail. The decomposition mechanism of RhB over Au/TiO₂-0 0 1 under visible light irradiation and the active species in the photocatalytic process had also been discussed. It is hoped that our work could render guided information for steering toward the design and application of noble metal/semiconductor nanocompositions with high visible-light photocatalytic activity.