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Synthesis, Characterization and Photoelectrochemical Properties of BiVO4 Porous Thin Films
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Zirak, Mohammad (Co-Supervisor)
Abstract
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...
Electrophoretic deposition of chitosan
, Article Materials Letters ; Volume 63, Issue 26 , 2009 , Pages 2253-2256 ; 0167577X (ISSN) ; Pishbin, F ; Boccaccini, A. R ; Sharif University of Technology
2009
Abstract
The electrophoretic deposition (EPD) of chitosan on metallic substrates was investigated. The electrophoretic mobility of the natural biopolymer in aqueous solution as a function of pH was studied. Because the protonation/deporotonation of chitosan is pH-dependent, the electrophoretic mobility and deposition rate is shown to increase with increasing pH from 2.9 to 4.1. The film growth rate is estimated to vary in the range 0.02-0.08 μm/s depending on the pH value. At high growth rates (> 0.05 μm/s), a porous film is obtained due to hydrogen entrapment. The EPD method developed here is applicable for the surface modification of metal implants by chitosan to develop novel bioactive coatings. ©...
Design and Fabrication of Flexible Fiber- Shaped Hybrid Micro- Supercapacitors Based on Carbon Nanostructures and Oxides, Sulfides and Phosphides of Some Transition Metals
, Ph.D. Dissertation Sharif University of Technology ; Shahrokhian, Saeed (Supervisor)
Abstract
Miniaturization of electronic devices with portable, flexible and wearable characteristics created a great demand for high-performance microscale energy storage devices with lightweight and flexible properties. Among the energy storage devices, wire-shaped micro-supercapacitors have recently received tremendous attention due to their small size, lightweght, and high flexibility. In the first part, the porous dendritic Ni-Cu film was prepared on Cu wire substrate (CW) for fabrication of high- performance wire-type micro-supercapacitors (micro-SCs). The porous structure with dendritic morphology provides a high surface area, short ion diffusion pathway and low contact resistance between...
How photocatalytic activity of the MAO-grown TiO2 nano/micro-porous films is influenced by growth parameters?
, Article Applied Surface Science ; Volume 256, Issue 13 , 2010 , Pages 4253-4259 ; 01694332 (ISSN) ; Golestani Fard, F ; Moshfegh, A. Z ; Sharif University of Technology
2010
Abstract
Pure titania porous layers consisted of anatase and rutile phases, chemically and structurally suitable for catalytic applications, were grown via micro-arc oxidation (MAO). The effect of applied voltage, process time, and electrolyte concentration on surface structure, chemical composition, and especially photocatalytic activity of the layers was investigated. SEM and AFM studies revealed that pore size and surface roughness of the layers increased with the applied voltage, and the electrolyte concentration. Moreover, the photocatalytic performance of the layers synthesized at medium applied voltages was significantly higher than that of the layers produced at other voltages. About 90% of...
Effect of film morphology on water oxidation enhancement in NiFeCo modified hematite photoanodes
, Article Surface and Coatings Technology ; Volume 421 , 2021 ; 02578972 (ISSN) ; Sobhkhiz Vayghan, N ; Esfandiar, A ; Dabirian, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Hematite (α-Fe2O3) is a promising candidate for water oxidation applications due to its abundance in the earth crust and its suitable bandgap. However, hematite performance is severely limited by electron-hole recombination at its interface with the electrolyte; something that can be addressed using electrocatalysts. In this report, we evaluate the influence of a ternary NiFeCo co-catalyst to enhance the water oxidation performance of hematite photoanodes. Thus, NiFeCo co-catalyst is optimized for hematite thin films with i) dense and ii) porous (nano-rod) morphologies. Both hematite films are prepared using electron beam evaporation method followed by an annealing step and NiFeCo...
On the photocatalytic activity of the sulfur doped titania nano-porous films derived via micro-arc oxidation
, Article Applied Catalysis A: General ; Volume 389, Issue 1-2 , 2010 , Pages 60-67 ; 0926860X (ISSN) ; Moshfegh, A. Z ; Golestani Fard, F ; Sharif University of Technology
2010
Abstract
Sulfur doped TiO2 layers containing nano/micro-sized pores were synthesized by micro-arc oxidation process. Effect of the applied voltage and the electrolyte composition on physical and chemical properties of the layers was investigated using SEM, AFM, XRD, XPS, and EDS techniques. A UV-vis spectrophotometer was also used to study optical properties of the layers. It was found that the doped layers were porous with a pore size of 40-170 nm. They consisted of anatase and rutile phases with varying fraction depending on the applied voltage and electrolyte concentration. Our XPS investigations revealed the existence of sulfur in the forms of S4+ and S6+ states which substituted Ti4+ in the...