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Effect of RGO/Zn:XCd1- xS crystalline phase on solar photoactivation processes
, Article RSC Advances ; Volume 6, Issue 52 , 2016 , Pages 46282-46290 ; 20462069 (ISSN) ; Tedadi, N ; Banazadeh, A ; Naseri, N ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
A series of reduced graphene oxide/ZnxCd1-xS (RGO/ZnxCd1-xS) nanocomposites (0 < x < 1) with different ratios of Zn/Cd were synthesized via a facile hydrothermal route under optimized experimental conditions and were carefully characterized by various techniques. Because very little is known about the morphology, specific surface area, and crystal phase effects of RGO/ZnxCd1-xS crystals on their photoresponsivity, field-emission scanning electron microscopy (FE-SEM), BET surface area analysis and X-ray diffraction (XRD) data were studied to investigate their effects on photoactivity. Based on the results, a crystal phase transition from a cubic phase in RGO/Zn0.9Cd0.1S to a hexagonal...
Fabrication and Investigation of Co3O4 Sponged Shape Nanostructured Supercapacitor Layer Electrodes Modified by Graphene
, Ph.D. Dissertation Sharif University of Technology ; Moshegh, Alireza (Supervisor) ; Naseri, Naima (Supervisor)
Abstract
Recently, Supercapacitors, as one of the most important energy storage devices, have attracted attensions by the scientists. Supercapcitor devices with appoporate design can store energy by two different mechanisms: i) physical (like conventional capacitors, i.e. by using polarization of the electrolyte, and ii) formation of electric double layer) and chemical mechanisms (like batteries, with reversible faradic reactions). These energy storage mechanisms allow these devices not only store high energy density but also they can provide high power density. In this project, two Co3O4/Co(OH)2 and Co3O4@Sponge-like rGO electrodes are made with chemical and electrochemical methods. To characterize...
Ti-rich TiO2 tubular nanolettuces by electrochemical anodization for all-solid-state high-rate supercapacitor devices
, Article ChemSusChem ; Volume 12, Issue 17 , 2019 , Pages 4064-4073 ; 18645631 (ISSN) ; Khajehdehi, O ; Sabbah, A ; Naseri, N ; Sharif University of Technology
Wiley-VCH Verlag
2019
Abstract
Supercapacitors store charge by ion adsorption or fast redox reactions on the surface of porous materials. One of the bottlenecks in this field is the development of biocompatible and high-rate supercapacitor devices by scalable fabrication processes. Herein, a Ti-rich anatase TiO2 material that addresses the above-mentioned challenges is reported. Tubular nanolettuces were fabricated by a cost-effective and fast anodization process of Ti foil. They attained a large potential window of 2.5 V in a neutral electrolyte owing to the high activation energy for water splitting of the (1 0 1) facet. Aqueous and all-solid-state devices showed diffusion time constants of 46 and 1700 ms, as well as...
RGO-α-Fe2O3/β-FeOOH ternary heterostructure with urchin-like morphology for efficient oxygen evolution reaction
, Article Journal of Electroanalytical Chemistry ; Volume 843 , 2019 , Pages 1-11 ; 15726657 (ISSN) ; Kowsari, E ; Seifvand, N ; Naseri, N ; Sharif University of Technology
Elsevier B.V
2019
Abstract
RGO-α-Fe2O3/β-FeOOH ternary heterostructure composite has been developed as an active photocatalyst for photoelectrochemical water splitting. RGO-α-Fe2O3/β-FeOOH has been successfully synthesized through one-pot hydrothermal-ionic liquid assisted route using tetrabutyl ammonium L-methioninate [TBA][L-Met]and graphene oxide (GO). The electrochemical studies were carried out to demonstrate the oxygen evolution reaction (OER)and photocatalytic activities. The overpotential reduction by rGO-α-Fe2O3/β-FeOOH sample was higher than the nanobean α-Fe2O3/β-FeOOH and pristine α-Fe2O3 samples. The photocurrent density enhanced for rGO-α-Fe2O3/β–FeOOH urchin-like structure and obtained as 0.62 mA·cm−2....
Synthesis, Characterization and Photoelectrochemical Application of ZnO Nanorods Sensitized by Graphene
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Naseri, Naeimeh (Co-Supervisor)
Abstract
According to the growth in the world population and the decrease in fossil fuels resources and also according to the pollution caused by these unrenewable resources, using hydrogen as an alternative energy resource seems to be unavoidable. In the past decades, semi-conductor metal oxides were being used widely in the energy domain of study, due to their appropriate band gap in the ultra-violet and visible spectra. Among these metal oxides, ZnO has been under special attention because of its electron mobility and its reasonable production cost and also its friendliness to environment. But the high band gap of ZnO (3.2 eV) has impeded its use in visible light spectrum. In this project,...
Synthesis and characterization of ZnO/g-C3N4 hybrid nanofibers photocatalyst for the removal of organic pollutants from water
, Article Iranian Journal of Physics Research ; Volume 20, Issue 2 , 2020 , Pages 273-280 ; Samadi, M ; Pourjavadi, A ; Moshfegh, A ; Sharif University of Technology
Isfahan University of Technology
2020
Abstract
ZnO/gC 3 N 4 hybrid nanofibers containing different concentrations of gC 3 N 4 nanosheets were prepared using electrospinning technique; this was followed by annealing at 460 forC for one hour in a box furnace. Based on scanning electron microscopy (SEM) image analysis, the mean diameter of the nanofibers was measured to be ~ 55 nm. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of ZnO and gC 3 N 4 in the prepared nanofibers. The photocatalytic activity of the nanofibers was examined under UV photoirradiation, showing that the ZCN0.5 nanofibers containing 0.5 wt% of gC 3 N 4exhibited the highest performance, as compared to other photocatalysts. The observed improvement...
Shed light on defect induced enhanced visible-light photocatalysis activity of rutile TiO2 nanoparticles: effects of annealing on blue-gray to light–gray transition
, Article Journal of Materials Research and Technology ; Volume 17 , 2022 , Pages 2400-2409 ; 22387854 (ISSN) ; Poursalehi, R ; Naseri, N ; Peymani, R ; Sharif University of Technology
Elsevier Editora Ltda
2022
Abstract
Preparation of the defective TiO2 nanoparticles (NPs) have been recently in particular interest for its outstanding applications in visible-light active photocatalysis. In order to make TiO2 visible-light absorber, optical band gap should be modified especially via introducing structural defects like oxygen vacancies as an effective pathway. In this research, we prepared defective rutile TiO2 NPs with highly efficient photocatalytic activity under visible light. The NPs were synthesized by electric arc discharge in water as a cost-effective and environmentally friendly method with capability of defect formation which followed by heat treatment. The photocatalytic activity improvement...
The Morphological Effects of Surface Modified Mos2 Nanosheets and Mos2 Qd/G-C3n4 Heterostructure Prepared by Chemical Methods in Hydrogen Evolution Reaction (Her)
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Naseri, Naeimeh (Co-Supervisor)
Abstract
The sustainable development in societies and the global energy challenge requires usage of clean energy systems that have attracted the attention of many researchers in recent decades. One of the major challenges in generating renewable resources is the problem of energy storage and imbalance between supply and demand cycles. Hydrogen as one of the clean energy carriers and due to having the highest energy density in terms of weight, is one of the important research topics. From this point of view, the preparation of electrocatalysts for hydrogen production, based on available materials, via simple and environmentally friendly production methods, was considered in this research....
Nanostructured materials for electronics and photonics
, Article Journal of Nanomaterials ; Vol. 2014 , 2014 ; ISSN: 16874110 ; Mishra, Y. K ; Naseri, N ; Nori, S ; Sharif University of Technology
2014
Abstract
[No abstract available]
MWCNT/WO3 nanocomposite photoanode for visible light induced water splitting
, Article Journal of Solid State Chemistry ; Volume 204 , 2013 , Pages 341-347 ; 00224596 (ISSN) ; Reyhani, A ; Naseri, N ; Moshfegh, A. Z ; Sharif University of Technology
2013
Abstract
The Multi-walled carbon nanotube (MWCNT)/WO3 nanocomposite thin films with different MWCNT's weight percentages were prepared by sol-gel method as visible light induced photoanode in water splitting reaction. Weight percentage of MWCNT in the all nanocomposite thin films was confirmed by TGA/DSC analysis. According to XPS analysis, oxygenated groups at the surface of the MWCNT and stoichiometric formation of WO3 thin films were determined, while the crystalline structure of the nanocomposite samples was studied by XRD indicating (0 0 2) peak of MWCNT in the monoclinic phase of WO3. The influence of different weight percentage (wt%) of MWCNT on WO3 photoactivity showed that the electron...
Optimal Ag concentration for H2 production via Ag:TiO 2 nanocomposite thin film photoanode
, Article International Journal of Hydrogen Energy ; Volume 37, Issue 4 , Feb , 2012 , Pages 3056-3065 ; 03603199 (ISSN) ; Kim, H ; Choi, W ; Moshfegh, A. Z ; Sharif University of Technology
2012
Abstract
TiO2 thin films containing different concentrations of Ag nanoparticles have been synthesized by sol-gel method. According to UV-visible spectra, presence of an intense surface plasmon resonance peak at 490 nm of wavelength indicated formation of silver nanoparticles in the TiO2 films. Based on atomic force microscopy (AFM) analysis, the surface roughness and the effective surface ratio increased by increasing the Ag mol%. Moreover, scanning electron microscopy (SEM) images showed formation of Ag nanoparticles on the surface for the samples containing high Ag concentration. X-ray diffraction (XRD) patterns revealed that the size of Ag nanocrystals increased by increasing the Ag content in...
The first study on enhanced photoresponsivity of ZnO-TiO2 nanocomposite thin films by anodic polarization
, Article Physical Chemistry Chemical Physics ; Volume 13, Issue 10 , Feb , 2011 , Pages 4239-4242 ; 14639076 (ISSN) ; Yousefi, M ; Moradlou, O ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
The physical and photoelectrochemical properties of the anodized ZnO-TiO2 thin films were investigated in this study. Impedance spectroscopy revealed a decrease in charge transfer resistance and Tafel plots determined enhancement of about 200 times in the exchange current (i 0) after anodization at high positive potential. It was found from XPS analysis that after applying the potential of 5 V to the ZnO-TiO2 photoelectrode, the lattice oxygen (O2-) in the thin film is oxidized to molecular oxygen and then, cations such as Zn2+ can be solved in the basic electrolyte and passed to the solution. Moreover, according to AFM analysis it was observed that the surface of the samples has been...
Implementation of Ag nanoparticle incorporated WO3 thin film photoanode for hydrogen production
, Article International Journal of Hydrogen Energy ; Volume 38, Issue 5 , 2013 , Pages 2117-2125 ; 03603199 (ISSN) ; Kim, H ; Choi, W ; Moshfegh, A. Z ; Sharif University of Technology
2013
Abstract
WO3 thin film photoanodes containing different concentrations of Ag nanoparticles were synthesized by solegel method. Based on UV-visible spectra, presence of a surface plasmon resonance peak at 470 nm of wavelength indicated formation of silver nanoparticles in the WO3 films. According to atomic force microscopy (AFM) analysis, the highest value for surface roughness and the effective surface ratio was observed for the sample containing 2 mol% of Ag. X-ray diffraction (XRD) patterns revealed that WO 3 nanocrystalline structure was formed in the monoclinic phase with the average size of about 18.2 nm while Ag nanocrystals were determined in cubic phase. X-ray photoelectron spectroscopy (XPS)...
Photoresponse and H2 production of topographically controlled PEG assisted Sol-gel WO3 nanocrystalline thin films
, Article International Journal of Hydrogen Energy ; Volume 36, Issue 21 , October , 2011 , Pages 13461-13472 ; 03603199 (ISSN) ; Yousefzadeh, S ; Daryaei, E ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
WO3 thin films were fabricated by sol-gel method using polyethylene glycol (PEG) as dispersing agent. Physical and photoelectrochemical properties of the synthesized nanocrystalline films were studied by varying weight ratio of PEG to tungsten precursor (x). Based on AFM observations and statistical modeling of the WO3 surface, the thickness of the films increased by increasing the amount of x with a nearly linear fashion while the surface roughness reached to a saturated value. However, the film synthesized with x = 4 showed a chaotic surface behavior. Optical analysis revealed that by increasing the x, transmittance of the films decreased while their band gap energies remained unchanged....
Improved electrochromical properties of sol-gel WO3 thin films by doping gold nanocrystals
, Article Thin Solid Films ; Volume 518, Issue 8 , 2010 , Pages 2250-2257 ; 00406090 (ISSN) ; Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
2010
Abstract
In this investigation, the effect of gold nanocrystals on the electrochromical properties of sol-gel Au doped WO3 thin films has been studied. The Au-WO3 thin films were dip-coated on both glass and indium tin oxide coated conducting glass substrates with various gold concentrations of 0, 3.2 and 6.4 mol%. Optical properties of the samples were studied by UV-visible spectrophotometry in a range of 300-1100 nm. The optical density spectra of the films showed the formation of gold nanoparticles in the films. The optical bandgap energy of Au-WO3 films decreased with increasing the Au concentration. Crystalline structure of the doped films was investigated by X-ray diffractometry, which...
Selecting Support Layer for Electrodeposited Efficient Cobalt Oxide/Hydroxide Nanoflakes to Split Water
, Article ACS Sustainable Chemistry and Engineering ; Volume 4, Issue 6 , 2016 , Pages 3151-3159 ; 21680485 (ISSN) ; Esfandiar, A ; Qorbani, M ; Moshfegh, A. Z ; Sharif University of Technology
American Chemical Society
2016
Abstract
Energy and environment crises motivated scientists to develop sustainable, renewable, and clean energy resources mainly based on solar hydrogen. For this purpose, one main challenge is the low cost flexible substrates for designing earth abundant efficient cocatalysts to reduce required water oxidation overpotential. Here, a systematic morphological and electrochemical study has been reported for cobalt oxide/hydroxide nanoflakes simply electrodeposited on four different commercially available substrates, titanium, copper sheet, steel mesh, and nickel foam. Remarkable dependence between the used substrate, morphology, and electrocatalytic properties of nanoflakes introduced flexible porous...
Sustainable starfish like cobalt electrocatalyst grown on optimized CNT-graphene hybrid host for efficient water oxidation
, Article Applied Surface Science ; Volume 524 , 15 September , 2020 ; Ghasemi, S ; Pourreza, M ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Solar energy generation is one of the most efficient approach to solve emerging environment and energy challenges. In this context, solar assisted dissociation of water into oxygen and hydrogen utilizing scalable and high performance electrocatalysts plays key role since the produced hydrogen is a clean energy carrier. Here, cobalt based nanoflakes with metallic core and oxidized surface were grown on the designed carbonaceous layer for anodic oxygen evolution reaction (OER) using an electrochemical approach. Carbonaceous layers containing proper amount of carbon nanotubes (CNT) and reduced graphene oxide (rGO) species were used to optimize the system. Although higher weight percent of rGO...
The effect of nanocrystalline tungsten oxide concentration on surface properties of dip-coated hydrophilic WO3-SiO2 thin films
, Article Journal of Physics D: Applied Physics ; Volume 40, Issue 7 , 2007 , Pages 2089-2095 ; 00223727 (ISSN) ; Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
2007
Abstract
WO3-SiO2 compound thin films were deposited on glass substrates using the sol-gel method, and then all the samples were dried at 100 °C and annealed at 400 °C in air. The effect of WO3 concentration on the hydrophilicity of WO3-SiO2 compound films was studied for the first time and it was shown that the films containing 85 mol% of the concentration possessed a superhydrophilic surface without UV or visible irradiation. Optical properties of the films such as transmittance, reflectance and bandgap energy were investigated using a UV-visible spectrophotometer. According to atomic force microscopy, the surface ratio was maximized in 85 mol% concentration of WO3 similar to hydrophilicity....
Comparison of logarithmic, elliptic, and conical helical spiral for isolation of circulating tumor cells based on inertial method
, Article Physics of Fluids ; Volume 34, Issue 9 , 2022 ; 10706631 (ISSN) ; Mozhdehbakhsh Mofrad, Y ; Safari, M ; Naseri, T ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
Cancer is one of the most significant causes of death in the world. It has been shown that the role of circulating tumor cells (CTCs) in the early detection of cancer is crucial. Since the number of these cancerous cells in blood is very rare, the inertial microfluidic devices are one of the best candidates for the isolation of CTCs because they result in a high throughput process. Consequently, they can process a large volume of blood in a short time. Despite extensive computational and experimental studies on inertial microfluidic platforms, the impact of the curvature has not been thoroughly investigated during separation. In this paper, the feasibility of isolation of CTCs for...
Kinetics and Mechanism of the Reduction of Hexavalent Chromium to Less Toxic Materials on ZnO Nanostructured Surfaces: the Effect of Wavelength and Light Intensity on the Reaction Rate
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Naseri, Ameneh (Supervisor)
Abstract
Hexavalent chromium ion (Cr+6) is a very toxic type of heavy metal in industrial effluents which is not biodegradable and accumulates in the human body that can cause genetic mutations and cancer. The aim of this project is to investigate the effect of wavelength and intensity of appropriate light on the reaction rate of photocatalytic reduction of Cr+6 ion to less toxic materials. In this project, we first designed and constructed a photocatalytic reactor to investigate the effect of wavelength and intensity of incident light on the reaction rate. The home-made photocatalytic reactor consisted of 120 LEDs in 12 different wavelengths, which has ability to control the intensity and...