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Electrochemical and Photocatalytic Behaviour of V&S Doped Titania Produced with Plasma Electrolytic Oxidation

Ahmadzadeh, Mohammad | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45773 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ghorbani, Mohammad
  7. Abstract:
  8. Plasma Electrolytic Oxidation is a new and promising method for synthesis of oxide layers and coatings on light metals such as titanium and aluminum. This method is a fast, easy and economicalway to produce TiO2 layers on Ti substrate. Photocatalytic properties of TiO2 can be improved with doping of other elements such as metals and non-metals by expanding its band gap which is in UV area of light spectrum in to visible area.Photocatalytic properties of TiO2 is also dependent on surface area and grain size, oxide layers which has been produced with PEO process has a high surface area due to its porosity. Voltage, electrolyte and additives concentration are among parameters which can affect band gap and porosity and consequently on photocatalytic properties of Titania. In this study Vanadium and Sulphur doped titania layers have been produced using different concentrations of sodium phosphate and sodium thiosulphate, and their electrochemical and morphological characteristics have been investigated with EIS, SEM, XRD .It has been observed that in high voltages and less vanadate concentrations anatase in the dominant phase. EDX studies show 1.2, 2 and 5 percent of vanadium in layers produced in electrolytes containing 0.25, 1 and 2 gr/L sodium vanadate and these layers showed 410, 430 and 472 nm absorption edges. Pore size increases with voltage and electrolyte concentration, in 2 gr/L vanadate solution pore size increases from less than a µm to more than 2 µm. EIS studies not only proves SEM results, also reveals a two layer surface with dense inner and porous outer layer. For photocatalytic properties, degradation of methyl orange has been studied under UV and Vis irradiation and it revealed high activity of V-doped and V&S doped TiO2under both UV and Vis irradiation V-doped layers has shown more activity than S- doped layers and both has more activity than Pure layers. The activity under UV irradiation is higher than Vis irradiation
  9. Keywords:
  10. Titanium Dioxide ; Porosity ; Plasma Electrolytic Oxidation ; Electrochemical Impedance Spectroscopy ; Vanadium Doped Layers ; Sulphure Doped Layers

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