Synergic photocatalytic effects of nitrogen and niobium co-doping in TiO₂ for the redox conversion of aquatic pollutants under visible light

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• 作者：Jonghun Lim ; Palanichamy Murugan ; Narayanan Lakshminarasimhan ; Jae Young Kim ; Jae Sung Lee ; Sang-Hyup Lee ; Wonyong Choi
• 关键词：Visible light photocatalysts ; Co-doping ; TiO2 ; Photocatalytic water purification ; Solar catalysis
• 刊名：Journal of Catalysis
• 出版年：February, 2014
• 年：2014
• 卷：310
• 期：Complete
• 页码：91-99
• 全文大小：2173 K

文摘

Nitrogen and niobium co-doped TiO₂ was synthesized by a simple sol-gel method and its visible light photocatalytic activities were compared with bare, N-, and Nb-doped TiO₂. The synthesized photocatalysts were characterized by powder X-ray diffraction (XRD), diffuse reflectance UV-Visible absorption spectroscopy, FT-IR spectroscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray analysis. TiO₂ co-doped with N and Nb can have unique properties distinguished from the singly doped TiO₂ in the aspects of the dopant-induced charge distribution, vacancy sites, structural stability, defect energy levels, and optical absorption. The most notable is that the visible light absorption by (N,Nb)-TiO₂ was significantly higher than either of N- or Nb-TiO₂ sample. The doped samples exhibited a slight change in the band gap (by 鈭?.1 eV) compared with bare TiO₂, which could be confirmed by Tauc plot, Mott-Schottky plot, and the electronic structure calculation. The co-doping of N and Nb in TiO₂ induced the creation of the mid-gap levels and Ti³⁺ states that enhance the visible light absorption. The photocatalytic activities of bare, N-, Nb-, and (N,Nb)-TiO₂ were compared for the photocatalytic degradation of 4-chlorophenol (4-CP), oxidation of iodide, and reduction of chromate (Cr^VI) in the aqueous phase under visible light (位 > 420 nm). For all tested substrates, (N,Nb)-TiO₂ exhibited the markedly higher activities than either N-TiO₂ or Nb-TiO₂. A similar trend was also observed for the photocurrent generation under visible light irradiation.