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Fabrication of Graphene/TiO2 Nanowalls as Visible Lights Photocatalysts

Rahimi, Kourosh | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43881 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Akhavan, Omid
  7. Abstract:
  8. TiO2 is known as a photocatalyst in near UV-Visible light region with better efficiency compared to other semiconductor photocatalysts. Many attempts have been done to increase the efficiency of this photocatalyst. also, application of 2D carbon nanostructures namely graphene for increasing the photocatalytic activity of TiO2 has shown positive results.
    In this research, we first synthesized Graphene Oxide (GO) suspension by exfolation of graphite oxide suspension. then we fabricated TiO2 thin films on glass substrates by so-called sol-gel method. finally we fabricate Graphene Oxide/TiO2 nanowalls composite films as a photocatalyst in visible light. X-ray photoelectron spectroscopy (XPS) demonstrated photocatalytic reduction of the graphene oxide sheets included in the composite with TiO2 films. Furthermore, annealing of composites at 450ºC in air resulted in formation of Ti-C and Ti-O-C bonds in the composite film which has a substantial delay in the recombination rate of the photoexcited electron-hole pairs and more efficient photocatalytic processes was yield.
    At last, the solar light-induced photocatalytic effects of the graphene-titanium oxide composite on activity of minuscule animals (C. elegans nematode and E. coli bacteria as their foods) was studied. The composite film showed a type of concentration-dependent cytotoxic effect on the nematodes under solar light irradiation. The rapid (4h) photoinactivation of the nematodes by the composite films was assigned to high generation of reactive oxygen species (ROS) under solar light irradiation (~25× of the ROS level of a control sample in dark), rather than the strong photoinactivation of E. coli bacteria which utilized as the food of the nematodes in a culture medium. The threshold ROS level for inactivation of the nematodes was found ~19× of the control level which was unreachable using pure TiO2 films
  9. Keywords:
  10. Graphine ; Titanium Dioxide ; Photocatalyst ; E.Coli Bacteria ; C.Elegans ; Cytoxicity ; Reactive Oxygen Species (ROS)

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