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electrochemical-impedance-spectroscopy
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Total 177 records
Probing the Performance of Safflower Plant as a Green Inhibitor with Molybdenum Disulfide on Corrosion Protection Properties of the Epoxy Coating
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadat Abadi, Ahmad (Supervisor) ; Mahdavian Ahadi, Mohammad (Supervisor)
Abstract
Today, the process of corrosion and compensation of minor injuries, without the need for tracing or any other physical interference, has become one of the subjects of interest to researchers. Inhibitors have been considered as one of the anti-corrosion agents. In this research, safflower extract as a green inhibitor in sodium chloride corrosive environment was used to evaluate the rate of corrosion of mild steel. Also the MoS2 nanoparticles were used as carrier of this green inhibitore in the epoxy coating to allow the activation of the coating in a scratched state in sodium chloride solution of 3.5%. In the first step, the extract of the safflower was prepared to reach the best part of this...
Synthesis, Characterization and Investigation of Electrocatalytic Activity of Nanoparticle/Cerium Oxide Composites in Oxygen Evolution and Reduction Reactions
, M.Sc. Thesis Sharif University of Technology ; Taherinia, Davood (Supervisor)
Abstract
The sluggish kinetics of oxygen evolution and reduction on the surface of electrodes is a major problem for the widespread use of devices that are based on sustainable, renewable and clean technologies, such as fuel cells and metal–air batteries. Therefore, the development of efficient and cost–effective materials for the oxygen evolution (OER: Oxygen Evolution Reaction) and reduction reactions (ORR: Oxygen Reduction Reaction) is highly desirable. In recent years, Metal–organic frameworks (MOFs) and their derivatives, have drawn considerable attention as potential catalysts and electrocatalyst due to their high surface area and porous structure. In this study, cerium (IV) oxide was...
Synthesis, Characterization and Investigation of Electrocatalytic Activity of Nanoparticle/Cerium Oxide Composites in Oxygen Evolution and Reduction Reactions
, M.Sc. Thesis Sharif University of Technology ; Taherinia, Davood (Supervisor)
Abstract
The sluggish kinetics of oxygen evolution and reduction on the surface of electrodes is a major problem for the widespread use of devices that are based on sustainable, renewable and clean technologies, such as fuel cells and metal–air batteries. Therefore, the development of efficient and cost–effective materials for the oxygen evolution (OER: Oxygen Evolution Reaction) and reduction reactions (ORR: Oxygen Reduction Reaction) is highly desirable. In recent years, Metal–organic frameworks (MOFs) and their derivatives, have drawn considerable attention as potential catalysts and electrocatalyst due to their high surface area and porous structure. In this study, cerium (IV) oxide was...
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...
Investigation of Electrocatalytic Activity of Metal-based Nanocomposites in the Reaction of Carbon Dioxide Reduction
, M.Sc. Thesis Sharif University of Technology ; Bastani, Darioush (Supervisor) ; Taherinia, Davood (Supervisor)
Abstract
Emissions of carbon dioxide (CO2) from fossil fuels are a potential issue for the global climate. One way to meet this challenge is to electrochemically convert CO2 molecules to reduced carbon species such as formates, alcohols, hydrocarbons, etc., which is a difficult process due to the poor kinetics of CO2 reduction. Therefore, the use of catalysts, while preventing undesirable side reactions, can also play an important role in reducing CO2. In this study, a two-step synthesis of CuS (1, 5, 12, 24 hr) @ Cu-MOF has been reported as an advanced electrocatalyst for CO2 reduction in neutral pH environments. Bismuth has been used to improve the electrocatalytic properties of the samples. Bi-CuS...
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...
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...
Formation of Zn-Ca-Ni tri cation's phosphate coating on steel and study that properties
, Article TMS 2009 - 138th Annual Meeting and Exhibition, San Francisco, CA, 15 February 2009 through 19 February 2009 ; Volume 1 , 2009 , Pages 615-623 ; 9780873397384 (ISBN) ; Afshar, A ; Sharif University of Technology
2009
Abstract
A new Zinc phosphating bath, which produces coatings at relatively lower temperatures within a reasonable time by using of chemical accelerators has been devised. Improvement of the bath performance by the addition of divalent cations like calcium, nickel has been studied. Bath formulation and operating conditions have been optimized by coating weight determinations. Stable samples of phosphating formulations with and without calcium and nickel salts were prepared and the structure and morphology of the phosphate coatings were determined by using X-ray diffraction (XRD) techniques, scanning electron microscopy. ASTMB117 salt spray test and electrochemical impedance spectroscopy (EIS) were...
Electrodeposition of Ni-WndashB nanocomposite from tartrate electrolyte as alternative to chromium plating
, Article Surface Engineering ; Volume 25, Issue 5 , 2009 , Pages 382-388 ; 02670844 (ISSN) ; Abdolmaleki, M ; Seyed Sadjadi, S. A ; Raghibi Boroujeni, M ; Arshadi, M. R ; Khoshvaght, H ; Sharif University of Technology
2009
Abstract
The effect of the bath chemistry and operating conditions on the chemical composition, microstructure and properties of NiWmdashB alloys deposited from tartrate baths on working electrode was studied for the first time by the pulsed current method. The investigations included the measurement of the current efficiencies and determination of the tungsten content in the electrodeposits. UV spectrometry was used for characterisation of complex formation. The grain size of deposits was determined by XRD. Also, the morphology of the deposits was studied by SEM. Amorphous NimdashWB alloys were successfully obtained by electrodeposition from the tartrate bath. The corrosion behaviour of NiWmdashB...
Estimation of the kinetic parameters of processes at the negative plate of lead-acid batteries by impedance studies
, Article Journal of Power Sources ; Volume 195, Issue 17 , September , 2010 , Pages 5789-5793 ; 03787753 (ISSN) ; Hejabi, M ; Gobal, F ; Sharif University of Technology
2010
Abstract
Impedance characteristics of the negative electrode of lead-acid battery were derived on the basis of fundamental interfacial processes occurring at the electrode. The solution of the governing equations was presented in terms of a simple equivalent circuit consisting of resistive and capacitive loops in which charge transfer and sulfate layer formation and also mass transfer (Warburg) elements are considered. The kinetic parameters were deduced by fitting the theoretically derived impedance to the experimental data. Impedance at various States of Charge (SoC) was also examined
Fabrication of self-organised highly ordered titanium oxide nanotube arrays by anodic oxidation and characterisation
, Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 297-309 ; 17469392 (ISSN) ; Ahadian, M. M ; Iraji Zad, A ; Taghavinia, N ; Dolati, A. G ; Sharif University of Technology
2010
Abstract
Self-organised and vertically oriented titanium oxide nanotube array (TNTA) has been synthesised by potentiostat anodisation of Ti foil in fluoride-based electrolyte. By varying the anodisation voltage from 8 V to 24 V it was possible to gradually change the topologies of nanotubes. The size of TNTAs was measured using SEM images and also determined based on a non-destructive optical method. In addition, photoelectrochemical properties of nanotubular TiO2/Ti electrodes were examined by anodic photocurrent response, potentiodynamic polarisation measurements and electrochemical impedance spectroscopy. A general equivalent circuit model was proposed for photoelectrochemical system consists of...
Electrochemically Assisted Photocatalytic Oxidation of Methanol on TiO2 Nanotube Arrays
, Article Journal of Materials Science and Technology ; Volume 26, Issue 6 , June , 2010 , Pages 535-541 ; 10050302 (ISSN) ; Irajizad, A ; Taghavinia, N ; Rahman, M ; Ahadian, M. M ; Sharif University of Technology
2010
Abstract
The influence of an externally applied bias on photocatalytic performance of crystallized TiO2/Ti nanotubular electrode formed by anodization in fluoride-based electrolyte were investigated and compared to the behavior of multiporous TiO2 electrode. The photoelectrocatalytic oxidation behavior of methanol over the nanotubular electrode has been studied by measuring photocurrent response, potentiodynamic polarization spectroscopy and using electrochemical impedance spectroscopy (EIS). It was found that the photoelectrocatalytic oxidation and the charge transfer rate constant of reaction on TiO2/Ti nanotubular electrode can significantly be increased by applying electrochemical bias. Moreover,...
A preliminary study of the electro-oxidation of l-ascorbic acid on polycrystalline silver in alkaline solution
, Article Journal of Power Sources ; Volume 195, Issue 1 , 2010 , Pages 165-169 ; 03787753 (ISSN) ; Gobal, F ; Sharif University of Technology
2010
Abstract
Electrochemical oxidation of l-ascorbic acid on polycrystalline silver in alkaline aqueous solutions is studied by cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (IS). The anodic electro-oxidation starts at -500 mV versus SCE and shows continued anodic oxidation in the cathodic half cycle in the CV regime signifying slowly oxidizing adsorbates. Diffusion coefficient of ascorbate ion measured under both voltammetric regimes is around 1.4 × 10-5 cm2 s-1. Impedance spectroscopy measures the capacitances associated with double layer and adsorption around 50 μF cm-2 and 4 mF cm-2 as well as the adsorption and decomposition resistances (rates). © 2009 Elsevier B.V. All...
A comparative investigation of the electrocatalytic oxidation of methanol on poly-NiTCPP and poly-TCPP/Ni modified glassy carbon electrodes
, Article Journal of Electroanalytical Chemistry ; Volume 663, Issue 1 , December , 2011 , Pages 14-23 ; 15726657 (ISSN) ; Haghighatbin, M. A ; Gobal, F ; Mahjani, M. G ; Rayati, S ; Sharif University of Technology
2011
Abstract
Electro-oxidation of methanol in alkaline solution at a glassy carbon electrode electrochemically modified by a conductive polymeric meso-tetra(4-carboxyphenyl)porphyrinato nickel(II), abbreviated as poly-NiTCPP and also meso-tetra(4-carboxyphenyl)porphyrin with incorporated nickel(II) cations, abbreviated as, poly-TCPP/Ni, were investigated and compared. Both films were prepared by oxidative electro-polymerization of complexes by repetitive cyclic voltammetry (RCV) in 0.1 M NaOH aqueous solution. The electrochemical properties and behaviors and also kinetic values of both films have been characterized and compared using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical...
Electrodeposition of Pt-Ru nanoparticles on multi-walled carbon nanotubes: Application in sensitive voltammetric determination of methyldopa
, Article Electrochimica Acta ; Volume 58, Issue 1 , 2011 , Pages 125-133 ; 00134686 (ISSN) ; Rastgar, S ; Sharif University of Technology
2011
Abstract
A modified glassy carbon electrode, prepared by potentiostatic electrodeposition of platinum-ruthenium nanoparticles (Pt-RuNPs) onto a multi-walled carbon nanotube (MWCNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric responses toward methyldopa (m-dopa) compared to glassy carbon electrodes individually coated with MWCNT or Pt-RuNPs. The surface morphology and nature of the hybrid film (Pt-RuNPs/MWCNT) deposited on glassy carbon electrodes was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. A remarkable enhancement in the microscopic area of the electrode together...
Anticorrosion properties of smart coating based on polyaniline nanoparticles/epoxy-ester system
, Article Progress in Organic Coatings ; Volume 75, Issue 4 , 2012 , Pages 502-508 ; 03009440 (ISSN) ; Shojaei, A ; Shariatpanahi, H ; Neshati, J ; Sharif University of Technology
2012
Abstract
In this study, the anticorrosive effect of dodecylbenzenesulfonicacid-doped polyaniline nanoparticles [n-PANI (DBSA)] as a conductive polymer was investigated using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) techniques. Initially, the n-PANI (DBSA) were successfully synthesized via inverse microemulsion polymerization leading to the spherical nanoparticles with an average diameter less than 30 nm. Two coating systems including 1 wt% n-PANI(DBSA) blended epoxy ester (n-PANI(DBSA)/EPE) and neat epoxy ester (EPE) were coated on the carbon steal substrate. The anticorrosion performance of the prepared coatings was studied using EIS measurement in 3.5%...
Effect of NaOH on the structure and corrosion performance of alumina and silica PEO coatings on aluminum
, Article Journal of Materials Engineering and Performance ; Volume 21, Issue 10 , October , 2012 , Pages 2195-2202 ; 10599495 (ISSN) ; Ehteshamzadeh, M ; Mirhosseini, S. M. M ; Sharif University of Technology
Springer
2012
Abstract
The effect of NaOH content of electrolyte on the properties of ceramic coatings, produced in silicate solution, was studied. Morphology, chemical analysis, phase composition, and cross-section of the ceramic coatings were investigated by SEM, EDS, XRD, and OM, respectively. The corrosion resistance and corrosion mechanism were also studied using potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5% NaCl solution. To study the surface roughness, a brightness SEM image analysis method was used. Results suggested that increasing the NaOH concentration of sediment production size causes thickness and coating roughness to decrease. The lowest corrosion rate belonged to...
Horseradish peroxidase immobilization on amine functionalized carbon nanotubes: Direct electrochemistry and bioelectrocatalysis
, Article Progress in Reaction Kinetics and Mechanism ; Volume 37, Issue 2 , May , 2012 , Pages 161-172 ; 14686783 (ISSN) ; Ghourchian, H ; Gholami, M. R ; Rafiee Pour, H. A ; Sharif University of Technology
2012
Abstract
Horseradish peroxidase (HRP) was successfully immobilized on amine functionalized TiO 2-coated multiwalled carbon nanotubes (NH 2-TiO 2-CNTs) by a convenient and efficient method. Electrochemical impedance spectroscopy, cyclic voltammetry and amperometry were applied to characterize the HRP/NH 2-TiO 2-CNT nano-composite. These techniques showed that the NH 2-TiO 2-CNTs greatly enhance the electron transfer between HRP and the modified electrode. Owing to the redox reaction of the electroactive centre of HRP, the HRP/NH 2-TiO 2-CNTs modified electrode exhibited a pair of quasi-reversible peaks with a peak-to-peak separation (ΔE p) of 70.6mV and a formal potential (E 0′) of -367.65mV (versus...