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Synthesis, Characterization and Photocatalytic Application of ZnO/g- C3N4 Composite Nanorods Fabricated by Combined Sol Gel-Hydrothermal Methods

Soltani, Mojtaba | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48980 (04)
  4. University: Sharif University of Technology
  5. Department: physics science
  6. Advisor(s): Moshfegh, Alireza
  7. Abstract:
  8. Because of the working conditions of semiconductors at ambient temperature and pressure, degradation of organic pollutants through semiconductors photocatalysis has attracted the interest of many researchers. Because of its large exciton binding energy,high chemical and physical stability,high electron and hole mobility, and low cost; zinc oxide, an n-type semiconductor with 3.2 eV direct band gap, is widely used in applications such as photocatalysts, solar cells, and light-emitting diodes. Among various morphologies of ZnO, 1D nanostructures such as nanowires and nanorods have recieved much attention due to their high surface to volume ratio. However, the application of ZnO as a photocatalyst is limited by its rapid hole-electron recombination and lack of visible light sensitivity, which makes up as much as 43% of solar spectrum. Coupling ZnO with visible light semiconductors is one of the available techniques for improving its photocatalytic properties. for this purpose(reducing recombination through coupling), graphite-like carbon nitride (g-C3N4) with 2.7 ev band gap which possesses appropriate features such as high thermal and chemical stability,effective surface area, and enviorment friendliness, is a novel and promising solution. In this project, ZnO NRs were synthesized on stainless steel mesh using hydrothermal method. The effect of different parameters such as hydrothermal reaction time, post heating temperature and annealing time were examined. In order to characterize synthesized ZnO NRs, UV-VIS spectroscopy, XRD, XPS and PL were used. Results showed that among different hydrothermal reaction times (1,3,7,10 h), 3h was optimum time. Because of increasing absorption by ZnO NRs, 550 0C and 15 min were optimum result for post-heating temperature and annealing time, respectively. Graphitic carbon nitride was added to ZnO NRs by using immersion method. Results showed that 3g urea in 20 cc methanol was optimum result among different masses of urea(1, 2, 3 ,3.5) in 20 cc methanol. Finally, photocatalytic activity of synthesized nanostructures was examined. For this purpose methylene blue was used as a dye. The highest MB photodegradation of 0.012 min 1 was measured for the ZnO NR samples prepared under growth time of 3h, post-heating temperature of 550 0C for 15 min. The highest MB photodegradation of .012 min-1 was measured for the g-C3N4/ZnO NRs composite for the samples prepared for the Urea mass of 3 g with immersion time of 30 min
  9. Keywords:
  10. Methylene Blue ; Zinc Oxide ; Sol-Gel Method ; Hydrothermal Method ; Nanorod ; Graphitic Carbon Nitride

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