Comparative study of photocatalytic activities of Ca₂Nb₂O₇ nanopolyhedra and TiO₂: Degradations of benzene and methyl orange

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• 作者：Shijing Liang^a ; Linrui Wen^a ; Guodong Liu^a ; Shuying Zhu^a ; Rusheng Yuan^a ; Ling Wu^a ; ^b ; ^{wuling@fzu.edu.cn}
• 关键词：Ca2Nb2O7 ; Benzene ; Deactivation ; Photocatalysis ; Comparative study
• 刊名：Catalysis Today
• 出版年：2013
• 出版时间：1 March, 2013
• 年：2013
• 卷：201
• 期：Complete
• 页码：175-181
• 全文大小：789 K

文摘

Ca₂Nb₂O₇ (CN) nanopolyhedra with relatively high surface area and small crystallites have been prepared by a microwave-assisted template-free hydrothermal method for the first time. The samples are characterized by powder X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), N₂-adsorption, and Transmission electron microscopy (TEM). A comparative study on the photocatalytic degradations of methyl orange (MO) in aqueous solution and benzene in gas phase has been carried out between Ca₂Nb₂O₇ nanopolyhedra and TiO₂. Results show that the MO and benzene could be effectively degraded and mineralized over the CN samples. Due to the higher photoabsorption performance and concentration of OH radicals, TiO₂ exhibit a superior photocatalytic activity for the degradation of MO compared with the CN samples. However, the weaker redox ability of the photogenerated hole-electron pairs induces the lower mineralization ratio of MO. Fourier transform infrared (FT-IR) analysis reveals that the photocatalytic active sites of TiO₂ have been blocked by stable intermediates, leading to the deactivation of the photocatalyst. In contrast, although the CN samples exhibit a lower photocatalytic degradation rate of MO, they show a much higher mineralization ratio of MO and benzene compared with TiO₂. Therefore, the CN samples maintain a clean surface during the photocatalytic process, resulting in a high and stable photocatalytic degradation performance. In addition, water plays a key role in the photocatalytic degradation of organic pollutants.