Flame-Made F-TiO2: An Efficient Second Generation Photocatalyst

  • Dr Wey Yang Teoh, ARC Centre of Excellence for Functional Nanomaterials, The University of New South Wales, Sydney, Australia
  • Mr Takayuki Fukahori, Department of Materials Science, Kyushu Institute of Technology, Kitakyushu, Japan
  • Mr Takaaki Kamai, Department of Materials Science, Kyushu Institute of Technology, Kitakyushu, Japan
  • Prof Teruhisa Ohno, Department of Materials Science, Kyushu Institute of Technology, Kitakyushu, Japan
  • Prof Rose Amal, ARC Centre of Excellence for Functional Nanomaterials, The University of New South Wales, Sydney, Australia

    • Recent breakthroughs in the modification of TiO2 photocatalysts by nonmetal-dopant has centred primarily around C, N and S elements. These dopants extend the absorption of the host materials to visible-light range, rendering them photocatalytically-active under UV and visible-light. In a less studied dopant, we have synthesised F-doped TiO2 in a rapid one-step Flame Spray Pyrolysis (FSP). FSP has been shown to yield highly-active photocatalysts of different types [1-4].

    Unlike other visible-light photocatalysts, F-doping did not shift the band-edge position of TiO2 to visible-light regime. The F-dopant has characterictic binding energy at 685eV, attributed to the ≡Ti-F species [5]. It is expected that the fluoride-doping induces F-type oxygen or Ti3+ vacancies. This is consistent with the increasing tail absorption in the visible-light range with increasing fluorine concentrations (F:Ti = 0.1-2.0).

    The F-TiO2 photocatalysts were highly active in mineralizing acetaldehyde under both UV (λ>350 nm) and visible-light (λ>420 nm). In fact the F-TiO2 was much more active than standard Degussa P25 and Ishihara ST-01 TiO2 even under UV-illumination. Similarly, F-TiO2 continues to show visible-light activity, while both P25 and ST-01 were relatively dormant. The visible light activity of F-TiO2 could be traced to the defect-induced extrinsic bandgap excitations [6].

    1. Teoh W.Y. et al. Chem. Eng. Sci. 60(2005)5852
    2. Teoh W.Y. et al. J. Catal. 251(2007)271
    3. Teoh W.Y. et al. Top. Catal. 44(2007)489
    4. Teoh W.Y. et al. Catal. Today 120(2007)203
    5. Park, H. et al. J. Phys. Chem. B 108(2004)4086
    6. Emeline A.V. et al. J. Phys. Chem. B 103(1999)9190