Loading...
Search for:
electrochemical-impedance-spectroscopy
0.011 seconds
Total 177 records
Robust water splitting on staggered gap heterojunctions based on WO3∖WS2–MoS2 nanostructures
, Article Renewable Energy ; Volume 162 , December , 2020 , Pages 504-512 ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The high charge carrier recombination rate and weak oxygen evolution kinetics have impeded the efficiency of WO3 photoelectrodes for water splitting. We present a novel type II heterojunction semiconductor based on mixed WS2 and MoS2 nanosheets on WO3 nanoflakes hydrothermally grown on highly porous W skeletons. The chemically exfoliated transition metal dichalcogenide (TMD) sheets with submicrometric lateral sizes were deposited on the surface of WO3 nanoflakes by the electrophoretic technique to fabricate a staggered gap heterojunction. The photoanode exhibited an impressive current density of 14.9 mA cm−2 at 1.23 VRHE which comprised ∼1.7 mA cm−2 photocurrent under 100 mW cm−2 simulated...
Fabrication of high conductivity TiO2/Ag fibrous electrode by the electrophoretic deposition method
, Article Journal of Physical Chemistry C ; Volume 112, Issue 47 , 2008 , Pages 18686-18689 ; 19327447 (ISSN) ; Taghavinia, N ; Sharifi, N ; Chavoshi, M ; Rahman, M ; Sharif University of Technology
2008
Abstract
TiO2 deposited on a membrane of Ag fibers was prepared as a photoelectrochemical cell electrode. Ag fibers were made by reduction of Ag complexes on cellulose fibers, followed by burning out the template. TiO 2 photocatalyst layers were grown on the fibers by electrophoretic deposition of TiO2 nanoparticles. Ag fibers could be uniformly deposited. Photocatalytic tests by dye decomposition and electrochemical impedance spectroscopy (EIS) under UV illumination demonstrate that Ag fibers act as a good substrate that provides both high surface area and good separation of photogenerated electron-hole pairs and causes the enhancement of photocatalytic activity in comparison with a thin film of...
The investigation of the kinetics and mechanism of hydrogen evolution reaction on tin
, Article International Journal of Hydrogen Energy ; Volume 32, Issue 12 , 2007 , Pages 1755-1761 ; 03603199 (ISSN) ; Jafarian, M ; Gobal, F ; Heli, H ; Mahjani, M. G ; Sharif University of Technology
2007
Abstract
The mechanism and kinetics of the hydrogen evolution reaction (HER) on tin electrode in 0.1 M H2SO4 solution were studied using the methods of steady-state polarization and electrochemical impedance spectroscopy. The simulation of the data obtained from these two methods, using nonlinear fitting procedure allowed us to determine the rate constants of Volmer, Heyrovsky and Tafel steps associated with the mentioned reaction. The kinetic results indicate that HER mechanism at low negative potentials is a serial combination of Volmer step and parallel Tafel and Heyrovsky steps. At high negative potentials where the hydrogen coverage reaches its limiting value, a Tafel line with the slope of -...
Kinetics and electrocatalytic behavior of nanocrystalline CoNiFe alloy in hydrogen evolution reaction
, Article International Journal of Hydrogen Energy ; Volume 32, Issue 12 , 2007 , Pages 1686-1693 ; 03603199 (ISSN) ; Azizi, O ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
2007
Abstract
Electrocatalytic activity of electrodeposited nanocrystalline CoNiFe alloy in hydrogen evolution reaction (HER) was studied in 1 M NaOH solution. The steady-state polarization measurement and electrochemical impedance spectroscopy were used to determine the Tafel slope, the exchange current density and the activation energy. The simulation of the data obtained from these two methods, using a nonlinear fitting procedure, allowed us to determine the surface coverage and the rate constants associated with the mentioned reaction. The ac-impedance spectra measured at various overpotentials in the HER region exhibited three semicircles in the complex plane plots. The high-frequency semicircle was...
Impedance spectroscopy study of aluminum electrocrystallization from basic molten salt (AlCl3-NaCl-KCl)
, Article Electrochimica Acta ; Volume 52, Issue 17 , 2007 , Pages 5437-5443 ; 00134686 (ISSN) ; Gobal, F ; Danaee, I ; Mahjani, M. G ; Sharif University of Technology
2007
Abstract
Aluminum electrocrystallization is studied by means of electrochemical impedance spectroscopy (EIS). A model based on random birth and deterministic growth of monolayers is proposed, in which the edges are assumed to follow a propagation law. The high frequency impedance data show charge transfer reaction of AlCl4- reduction while the low frequency features signifies the growth mode of deposits. The inductive response observed in the course of polycrystalline deposition reflects the activation of electrode area while a capacitive loop appears in regular growth. Parameters of impedance model in this system can be calculated from the fitting of experimental data to the Faradaic impedance...
Electrochemical Hydrogen Generation Using Metal Organic Frameworks Derived Catalysts
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohamad Reza (Supervisor)
Abstract
In recent years, the widespread investigation on multi-transition metal oxides that with two or more transition metal oxides, have been increased rapidly for electrochemical application due to low cost, high conductivity and good electrochemical performance other than single metal oxides. In this project, CuCo2O4 nanoparticles were firstly fabricated by decomposing of CuCo-MOF as the template. The as prepared samples were used to synthesis a new nanocomposite of MoS2 and CuCo2O4. The best ratio of the two component were optimized to prepare the best electrocatalyst for Hydrogen evolution reaction (HER). The structure of prepared nanocomposite were investigated by various techniques such as...
Facile and ultra-sensitive voltammetric electrodetection of Hg2+in aqueous media using electrodeposited AuPtNPs/ITO
, Article Analytical Methods ; Volume 13, Issue 24 , 2021 , Pages 2688-2700 ; 17599660 (ISSN) ; Siavash Moakhar, R ; Sharifi Abdar, P ; Zargarnezhad, H ; Shone, M ; Rahmani, A. R ; Moradi, N ; Niksefat, V ; Shayar Bahadori, K ; Dolati, A ; Sharif University of Technology
Royal Society of Chemistry
2021
Abstract
In this study, we have investigated the use of electrodeposited Au-Pt nanoparticles (AuPtNPs) on indium tin oxide (ITO) for the detection of Hg2+ heavy ions in water samples. The mechanism of AuPtNP electrocrystallization on ITO glass in an aqueous solution containing 0.5 mM HAuCl4 + 0.5 mM H2PtCl6 is described for the first time. The nucleation mechanism of monometallic AuNPs on ITO was found to be progressive; however, a transition from progressive to instantaneous was observed for bimetallic AuPtNPs at elevated overpotentials. The modified ITOs were then assessed for the electrodetection of Hg2+ in aqueous media. It was shown by differential pulse voltammetry (DPV) that the sensitivity of...
Synthesis and characterization of highly hydrophilic self-associating terpolymers: Rheological, thermal, and corrosion protection studies
, Article Chemical Engineering Journal ; Volume 405 , 2021 ; 13858947 (ISSN) ; Ramazani Saadatabadi , A ; Haddadi, S. A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
In this study, water-soluble terpolymers containing highly hydrophilic monomers of acrylamide and maleic anhydride and highly hydrophobic monomers of styrene were synthesized (ASM) through the one-step inverse emulsion polymerization. Proton nuclear magnetic resonance (1H NMR), fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction pattern (XRD) were performed to investigate the chemical structures and structural transformations of ASM. Thermal stability and thermal decomposition steps of ASM were studied by thermogravimetric analysis (TGA). An Ubbelhode capillary viscometer and a rheological mechanical spectrometer (RMS) were employed to obtain the specific, relative, and...
PVDF/PU blend membrane separator for lithium-ion batteries via non-solvent-induced phase separation (NIPS)
, Article Journal of Solid State Electrochemistry ; Volume 25, Issue 8-9 , 2021 , Pages 2385-2394 ; 14328488 (ISSN) ; Fathollahi Zonouz, A ; Soltanieh, M ; Mousavi, S. A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
Membrane separator based on the polyvinylidene fluoride (PVDF) is prepared via the non-solvent-induced phase separation (NIPS) method with water and ethanol as non-solvent and a mixture of dimethylformamide (DMF) and acetone as solvent. The effect of various acetone/DMF ratios and non-solvent material on the physical and electrochemical properties of the separator is studied by FE-SEM, tensile strength, electrochemical AC-impedance spectroscopy (EIS), thermal stability, and linear sweep voltammetry (LSV). The charge-discharge studies are carried out by fabricating a lithium foil/polymer electrolyte membrane/LiFePO4 cell. The results show that with the change of solvent and non-solvent, the...
Smoothing and coverage improvement of SnO2 electron transporting layer by NH4F treatment: Enhanced fill factor and efficiency of perovskite solar cells
, Article Solar Energy ; Volume 228 , 2021 , Pages 253-262 ; 0038092X (ISSN) ; Zamani Meymian, M. R ; Mohamadkhani, F ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Surface modification of SnO2 electron transporting layer (ETL) plays a critical role in the performance of SnO2-based planar perovskite solar cells (PSC). Here, we show how long-time NH4F-based water bath treatment of SnO2 layer makes smoothing and morphological improvements and enhances the device performance. Recently it was shown that short-time NH4F treatment (2 sec) with spin coating method reduces interface traps by improving surface chemistry. Here we observe the smoothing of SnO2 films as a result of long-time NH4F treatment, which could be a result of a slight etching-deposition process. Absorption and resistivity measurements indicate that SnO2 etching process is involved in...
Anodic pulse electrodeposition of mesoporous manganese dioxide nanostructures for high performance supercapacitors
, Article Journal of Alloys and Compounds ; Volume 887 , 2021 ; 09258388 (ISSN) ; Javanbakht, M ; Shahrokhian, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A pseudocapacitive electrode based on mesoporous manganese dioxide (MnO2) was fabricated via the anodic pulse electrodeposition method. Pulse current (PC) has many parameters that affect the physicochemical and electrochemical properties of the material. PC parameters are generally divided into independent and dependent types. Independent pulse parameters consist of the time of applying current (ton), interval time with zero current (toff), and peak current density (Ip). Dependent pulse parameters include duty cycle (θ), frequency (f), and average current density (Ia). In this work, the changes of two independent parameters (ton and toff) at the constant Ip = 2 mA cm-2 on the anodic pulse...
Synthesis and characterization of polyaniline/nanodiamond hybrid nanostructures with various morphologies to enhance the corrosion protection performance of epoxy coating
, Article Diamond and Related Materials ; Volume 120 , 2021 ; 09259635 (ISSN) ; Shojaei, A ; Rahmani, P ; Pirhady Tavandashti, N ; Amouzegar, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this study, nano-sized diamond particles (ND) were functionalized in two consecutive stages. First, dry thermal oxidation was employed to obtain carboxylated ND. In the next step, carboxylated ND was properly surface modified through wet chemistry to acquire aminated-ND (ND-NH2). Then, polyaniline (PANI) was synthesized in the presence of aminated-ND particles at a broad concentration from 1 wt% to 70 wt% to obtain PANI/ND hybrid nanostructures. The chemical structure, morphology, and thermal stability of nanoparticles were comprehensively characterized by different techniques such as FT-IR, UV–visible, TGA, XRD, FESEM, and TEM. It was observed that the morphology of PANI/ND...
Magnetic nanofluidic electrolyte for enhancing the performance of polysulfide/iodide redox flow batteries
, Article Electrochimica Acta ; Volume 369 , 2021 ; 00134686 (ISSN) ; Molaei Dehkordi, A ; Roberts, E. P. L ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this article, the novel concept of using magnetic nanofluidic electrolyte for redox flow batteries is demonstrated for the first time. In this regard, the stable magnetic nanofluidic electrolytes are prepared by dispersing magnetic modified multiwalled carbon nanotubes (MMWCNTs) in the positive electrolyte of a polysulfide-iodide redox flow battery at mass concentrations of less than 0.3 g L−1. The electrochemical behavior of magnetic nanofluidic electrolyte was examined using cyclic voltammetry at different mass concentrations of MMWCNTs with a carbon felt electrode. Higher and stable peak current densities were observed at larger mass concentrations of MMWCNTs. A polysulfide-iodide...
Water repellent room temperature vulcanized silicone for enhancing the long-term stability of perovskite solar cells
, Article Solar Energy ; Volume 218 , 2021 , Pages 28-34 ; 0038092X (ISSN) ; Heydari, M ; Mohammadi, M ; Parand, P ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A key direction toward enhancing the long term and outdoor stability of the perovskite solar cells is encapsulation. As a result, a suitable encapsulation package is required to prevent moisture and oxygen penetration toward the perovskite solar cells. In this work, a low-cost commercially available bilayer structure of poly (methyl methacrylate)/ room-temperature vulcanizing silicone rubber (RTV) encapsulation package for enhancing the long term stability of the perovskite solar cells has been investigated. Encapsulated cells retained more than 80% of the initial efficiency at the environmental condition of 50% moisture, and room temperature after 1000 h, however reference cell efficiency...
In vitro study: Bond strength, electrochemical and biocompatibility evaluations of TiO2/Al2O3 reinforced hydroxyapatite sol–gel coatings on 316L SS
, Article Surface and Coatings Technology ; Volume 405 , 2021 ; 02578972 (ISSN) ; Afshar, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid...
Synergistic effects of MWCNT and high-pressure torsion-induced grain refinement on microhardness, tribological properties, and corrosion behavior of Cu and Cu/MWCNT nanocomposites
, Article Metals and Materials International ; 2021 ; 15989623 (ISSN) ; Mirabad, H. M ; Golenji, R. B ; Kakaei, K ; Kim, H. S ; Sharif University of Technology
Korean Institute of Metals and Materials
2021
Abstract
In this study, ultra-fine grained Cu and Cu + carbon nanotube (CNT) nanocomposites were prepared through a processes combining flake powder metallurgy, hot pressing, and high-pressure torsion (HPT). The effects of grain refinement and CNT reinforcement on the microstructure, hardness, wear resistance, and corrosion behavior of the newly developed nanocomposites were investigated. The results indicated that the HPT process decreased the grain size of Cu and Cu + CNT by 67.7% and 68.1%, respectively, and increased their microhardness by 151% and 132%. The addition of CNTs substantially improved the tribological behavior of Cu by generating a mechanically mixed carbon- and oxide-rich layer....
In vitro study: Bond strength, electrochemical and biocompatibility evaluations of TiO2/Al2O3 reinforced hydroxyapatite sol–gel coatings on 316L SS
, Article Surface and Coatings Technology ; Volume 405 , 2021 ; 02578972 (ISSN) ; Afshar, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid...
Synergistic effects of MWCNTs and high-pressure torsion-induced grain refinement on microhardness, tribological properties, and corrosion behavior of Cu and Cu/MWCNT nanocomposites
, Article Metals and Materials International ; 2021 ; 15989623 (ISSN) ; Mirabad, H. M ; Golenji, R. B ; Kakaei, K ; Kim, H. S ; Sharif University of Technology
Korean Institute of Metals and Materials
2021
Abstract
In this study, ultra-fine grained Cu and Cu + carbon nanotube (CNT) nanocomposites were prepared through a processes combining flake powder metallurgy, hot pressing, and high-pressure torsion (HPT). The effects of grain refinement and CNT reinforcement on the microstructure, hardness, wear resistance, and corrosion behavior of the newly developed nanocomposites were investigated. The results indicated that the HPT process decreased the grain size of Cu and Cu + CNT by 67.7% and 68.1%, respectively, and increased their microhardness by 151% and 132%. The addition of CNTs substantially improved the tribological behavior of Cu by generating a mechanically mixed carbon- and oxide-rich layer....
Al-doped Li7La3Zr2O12 garnet-type solid electrolytes for solid-state Li-Ion batteries
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 5 , 2021 , Pages 6369-6378 ; 09574522 (ISSN) ; Golmohammad, M ; Soleimany Mehranjani, A. R ; Faghihi Sani, M ; Sharif University of Technology
Springer
2021
Abstract
Cubic phase Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for next-generation Li-ion batteries. In this work, the combustion sol–gel technique is used to prepare an Al-doped LLZO solid electrolyte. The crystal structure is investigated, and the cubic phase is confirmed. Densification properties were investigated using SEM and optical dilatometry. The densification of the Al-doped sample takes place in two stages through two different shrinkage rates. Using 0.25 mol Al-dopant 94% relative density is achieved at 1100 °C. The effect of Al-doping on electrochemical properties is investigated in detail using AC impedance spectroscopy. The result indicates that the optimum concentration of...
Epoxy nanocomposite coatings with enhanced dual active/barrier behavior containing graphene-based carbon hollow spheres as corrosion inhibitor nanoreservoirs
, Article Corrosion Science ; Volume 185 , 2021 ; 0010938X (ISSN) ; Ramazani Saadatabadi, A ; Mahdavian, M ; Arjmand, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Graphene-based carbon hollow spheres (CHSs) fabrication, doped with 2-mercaptobenzimidazole (MBI) was successfully done in previous work. The active/barrier corrosion protection performance (CPP) of epoxy coatings was evaluated using salt spray test, electrochemical impedance spectroscopy (EIS), and scanning vibrating electrode technique (SVET). Results proved the active/barrier CPP enhancement of epoxy coatings in the presence of 3 wt. % MBI@CHSs. While the presence of MBI and empty CHSs in epoxy coatings did not further improve the active performance. An improvement in the adhesion loss of the epoxy coating, ca. 58 %, was observed in the presence of 3 wt. % MBI@CHSs. © 2021