Excellent Sun-Light-Driven Photocatalytic Activity by Aurivillius Layered Perovskites, Bi5鈥?i>xLaxTi3FeO15 (x = 1, 2)

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• 作者：Gollapally Naresh ; Tapas Kumar Mandal
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：December 10, 2014
• 年：2014
• 卷：6
• 期：23
• 页码：21000-21010
• 全文大小：717K
• ISSN：1944-8252

文摘

Aurivillius phase layered perovskites, Bi_5鈥?i>xLa_xTi₃FeO₁₅ (x = 1, 2) are synthesized by solid-state reaction. The compounds are characterized by powder X-ray diffraction (PXD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), UV鈥搗is diffuse reflectance (UV鈥搗is DRS), and photoluminescence (PL) spectroscopy. UV鈥搗is DRS data revealed that the compounds are visible light absorbing semiconductors with band gaps ranging from 鈭?.0鈥?.7 eV. Photocatalytic activity studies by Rhodamine B (RhB) degradation under sun-light irradiation showed that these layered oxides are very efficient photocatalysts in mild acidic medium. Scavenger test studies demonstrated that the photogenerated holes and superoxide radicals (O₂鈥⑩€?/sup>) are the active species responsible for RhB degradation over the Aurivillius layered perovskites. Comparison of PL intensity, dye adsorption and 味-potential suggested that a slow e鈥?/sup>鈥揾⁺ recombination and effective dye adsorption are crucial for the degradation process over these photocatalysts. Moreover, relative positioning of the valence and conduction band edges of the semiconductors, O₂/O₂鈥⑩€?/sup>, 鈥?/sup>OH/H₂O potential and HOMO鈥揕UMO levels of RhB appears to be responsible for making the degradation hole-specific. Photocatalytic cycle tests indicated high stability of the catalysts in the reaction medium without any observable loss of activity. This work shows great potential in developing novel photocatalysts with layered structures for sun-light-driven oxidation and degradation processes largely driven by holes and without any intervention of hydroxyl radicals, which is one of the most common reactive oxygen species (ROS) in many advanced oxidation processes.r>

Keywords:

Bi_5鈭?i>xLa_xTi₃FeO₁₅ (x = 1, 2); layered perovskites; Aurivillius phases; photocatalysis; rhodamine B