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Improvement of Photocatalytic Efficiency of Nano-Titania Compsites

Koohestani, Hassan | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 47577 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Sadrnezhad, Khatiboleslam
  7. Abstract:
  8. Semiconductor-based photo catalysts, titanium dioxide (TiO2) especially, have been extensively studied for the oxidative photo destruction of organic pollutants in wastewaters and hydrogen production as a green energy source. Much effort has been made to remove the restrictions on the use of TiO2 and challenges related to the recovery of powdery photocatalysts. In this study, copper oxide (CuO) and Zirconium oxide (ZrO2) were used to synthesize nanocomposites. Composition of TiO2/CuO and TiO2/ZrO2 with different weight percentages of second dioxide was synthesized by chemical methods and structural properties of samples were studied by X-ray diffraction and scanning electron microscopy. Other properties such as specific surface area, the absorption of infrared and UV-vis and thermal changes were also studied. Then photocatalytic property was evaluated by using dye degradation analysis and removal of methyl orange. Pure TiO2 synthesized at 450°C was obtained with two phases of anatase and rutile, 68m2/g specific surface area and 91.2eV band gap. Copper oxide reduced the band gap and the specific surface of composite catalysts and TiO2-7.5% CuO composite with 48.2eV band gap and 57.8m2/g specific surface area showed higher degradation efficiency. Despite the reduction in surface area of composites by zirconium oxide, band gap increased. TiO2-10% ZrO2 sample with 85.5m2/g surface area and 3.10eV band gap provided better degradation efficiency. In the next step, the effect of adding silver and geometry on the various properties of the composites were determined. The results of dye degradation showed that addition of 1.5% Ag to TiO2-7.5%CuO and 1% Ag to TiO2-10%ZrO2 has created an appropriate increase in efficiency. Despite its smaller surface area compared to that of the powder, the network geometry showed better results than the other two geometries. Finally, analysis of water splitting and hydrogen production were investigated. The amount of hydrogen production was measured by gas chromatography. Hydrogen production efficiency of TiO2-7.5%CuO and TiO2-10%ZrO2 samples were obtained 3500 and 5000 µm, respectively
  9. Keywords:
  10. Titanium Dioxide ; Water Analysis ; Methyl Orange ; Titanium Dioxide/Copper Oxide ; Titanium Dioxide/Zirconium Dioxide ; Fiber Geometry ; Network Geometry

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