| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 61034 | Journal of Catalysis | 2014 | 9 Pages |
•The (N,Nb)-TiO2 has unique properties distinguished from the singly doped TiO2.•The (N,Nb)-TiO2 creates impurity levels with enhanced absorption of visible light.•The photoactivities of (N,Nb)-TiO2 is markedly higher than singly doped TiO2.
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 ∼0.1 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 (CrVI) in the aqueous phase under visible light (λ > 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.
Graphical abstractTiO2 samples doped with both N and Nb were synthesized by a simple sol–gel method and characterized by various spectroscopic tools. The marked synergic effect of co-doping N and Nb in TiO2 was demonstrated for the visible light-induced conversion of selected aquatic pollutants.Figure optionsDownload full-size imageDownload high-quality image (102 K)Download as PowerPoint slide
