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Synthesis, Characterization and Photoelectrochemical Properties of BiVO4 Porous Thin Films

Rasouli Ardalani, Abolfazl | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54562 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Moshfegh, Alireza; Zirak, Mohammad
  7. Abstract:
  8. Synthesis, characterization and photoelectrocatalytic performance evaluation of worm-like BiVO4 porous films have been conducted in this research. An in situ combustion approach was employed to prepare BiVO4 nanolayers on glass and ITO/glass by using drop casting, spin coating, dip coating and pulsed spray pyrolysis deposition techniques. The precursor solution of vanadium and bismuth include ~0.0233g ammonium metavanadate (NH4VO3) and ~0.0970g bismuth (III) nitrate pentahydrate (Bi(NO3)3.5H2O) in 2.5 mL ethylene glycol. Different deposition parameters were investigated for each of the aforementioned deposition techniques to obtain a uniformly-deposited BiVO4 nanolayer with high adhesion to the substrate on a large scale with acceptable reproducibility. Interestingly, such desired layers were obtained with the optimized pulsed spray pyrolysis deposition parameters, namely substrate temperature (Ts = 200°C), nozzle-to-substrate distance (D = 40cm), carrier gas pressure (P = 3 atm), nozzle diameter (d=0.1mm), pulse time (tp = 1min), interval between pulses (tint= 0.5 min) and pulse number (N = 14). Through analysis of XRD pattern obtained for the optimized layer, apparent crystallite size (15 ± 5 nm) and lattice constants were estimated. Tetragonal scheelite phase was found to be the dominant phase in the as-prepared samples. SEM top-view images indicated pore sizes of 162 ± 94 nm and worm-like fine grain diameters of 208 ± 53 nm. The best photocurrent density obtained ( 41.8 µA/cm2 ) belongs to samples prepared by spin coating. Effect of an electrochemical treatment, applied to produce oxygen vacancies inside the layers, was investigated on (photo)electrochemical properties of the samples. This treatment increased the effective life time of charge carriers from 13.2 ms to 25.2 ms in the dark
  9. Keywords:
  10. In-Situ Combustion ; Porous Films ; Electrochemical Treatment ; Bismuth Vanadate ; Electrochemical Reduction ; Oxygen Vacancy

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