Enhanced Photocatalytic Activity of Nano-scaled TiO2 Co-doped with N and Ag by Sol-gel Method

Azimi, Zahra | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45762 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Dolati, Abolghasem
  7. Abstract:
  8. Transparent coatings with self-cleaning property in visible light spectrum, UV radiation resistance and antimicrobial are highly desirable. Titanium dioxide (TiO2) is used in this research has been widely studied as an efficient photocatalyst by researchers. In this research enhanced visible-light photocatalytic activity is gained with N and Ag co-doped titania. All samples were annealed at 450℃. Finally AgI was loaded TiO2 coating and the results were investigated. Peaks of XRD pattern wereattributed to different diffraction planes of anatase TiO2. Morphology of coatings were analyzed with using FE-SEM. Nano granis size of TiO2 and AgI loaded TiO2 were observed in FE-SEMimages. Nitrogen doped and nitrogen-silver co-doped TiO2 were successfully detected by X-ray photoelectron spectroscopy (XPS). Analysis reveal that silver doped into TiO2 lattices in the form of Ag0 and Ag+. According to binding energy results, Nitrogen substituted some of the oxygen sites in samples made by water base sol and interstitial doping of N was in samples made with alcohol base sol.Based on the results of UV-Vis test, with doping Ag and N into TiO2, the absorption edge of TiO2 was shifted to a longer wavelength. The co-doping of TiO2with nitrogen and Ag has led to the narrowing of the band gap so with co-doping of 9 at% Nitrogen and Ag up to 0.42 at% band gap of TiO2 has decreased to 2.88 eV and 2.72 eV in alcohol and water base coatings respectively. Both nitrogen and nitrogen-silver co-doping led to an increase in degradation rate of equeous methyl orange (MO). The N-Ag co-doped TiO2 samples exhibited much higher photocatalytic activities than those doped with nitrogen alone under UV light. Hydrophilicity of coatingswas determined by measuring contact angle of water drop with surface and the results have shown that Ag-N co-doped titania can maintain its hydrophilicity in dark places for a long time.Two component coating of TiO2-AgI was created on single layer of TiO2 and AgI has shifted absorption edge of titania to a longer wavelength. This new photocatalyst coating showed remarkable activities in the decolorisation of methyl orange (MO). It was seen that two component coating of TiO2 codoped with 9at% Nitrogen, 42 at% Ag and AgI which has the lowest band gap and a highest photocatalicity activity between samples, can save its hydrophilic property in darkenvironments for a long time
  9. Keywords:
  10. Hydrofilicity ; Photocatalyst ; Sol-Gel Method ; Nanostructured Coating ; Titanium Oxide Coating ; Nitrogen ; Silver

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