Search for: cyclic-voltammetry
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    Electrocatalytic oxidation of methanol on a nickel electrode modified by nickel dimethylglyoxime complex in alkaline medium

    , Article Journal of Power Sources ; Volume 144, Issue 1 , 2005 , Pages 21-27 ; 03787753 (ISSN) Golikand, A. N ; Shahrokhian, S ; Asgari, M ; Ghannadi Maragheh, M ; Irannejad, L ; Khanchi, A ; Sharif University of Technology
    Electrocatalytic oxidation of methanol on a nickel disc electrode coated with nickel dimethyglyoxime complex (NiDMG), conditioned by potential recycling in a potential range of 100-700 mV (versus SCE) is studied by cyclic voltammetry in alkaline medium (0.10 M NaOH). The results show that the NiODMG layer formed at the surface of electrode behaves as an efficient electrocatalyst for the oxidation of methanol in alkaline medium via Ni(III) species with the cross exchange reaction occurring through out the layer at a low concentration of methanol. A plausible mechanism was proposed for catalytic oxidation of methanol at this modified electrode. Moreover, the effects of various parameters such... 

    Voltammetric studies of a cobalt(II)-4-methylsalophen modified carbon-paste electrode and its application for the simultaneous determination of cysteine and ascorbic acid

    , Article Electrochimica Acta ; Volume 50, Issue 1 , 2004 , Pages 77-84 ; 00134686 (ISSN) Shahrokhian, S ; Karimi, M ; Sharif University of Technology
    A carbon-paste electrode (CPE) chemically modified with the cobalt(II)-4-methylsalophen (CoMSal) as a Schiff base complex was used as a highly sensitive and fairly selective electrochemical sensor for simultaneous, determination of minor mounts of ascorbic acid (AA) and cysteine. This modified electrode shows very efficient electrocatalytic activity for anodic oxidation of both AA and cysteine via substantially decreasing of anodic overpotentials for both compounds. The. mechanism of electrochemical oxidation of both AA and cysteine using CoMSal-modified electrode was thoroughly investigated by cyclic voltammetry and polarization studies. Results of cyclic voltammetry (CV) and differential... 

    Voltammetric Determination of Tryptophan and 5-Hydroxytryptophan Using Graphite Electrode Modified with a Thin Film of Graphite/Diamond Nano-mixture And Determination of omeprazole Using Graphite Electrode

    , M.Sc. Thesis Sharif University of Technology Bayat, Maryam (Author) ; Shahrokhian, Saeed (Supervisor)
    At the first part of this thesis, a pyrolitic graphite electrode (PGE) modified with graphite/nanodiamond film (GND) was applied as a sensitive electrochemical sensor for determination and study of electrochemical behavior of tryptophan (Trp) and 5-hydroxytryptophan (5-HTP) in aqueous solutions. The results showed that GND caused a remarkable increase in the peak currents so the GND/PGE electrode surface was more sensitive to the concentration of Trp and 5-HTP than the PGE surface. The determination of Trp and 5-HTP were investigated by stripping voltammetry. Experimental parameters such as scan rate, pH, accumulation conditions and amount of the modifier used on the PGE surface were... 

    Synthesis and Electrochemical Study of Endohedral Fullerenes Prepared by Arc Vaporizing Method

    , M.Sc. Thesis Sharif University of Technology Hashemi, Ali (Author) ; Ghanbari, Bahram (Supervisor)
    Fullerenes are molecular solid materials which are composed of 3D closed shell carbon-only structure. As soon as mass production of fullerenes was performed, the synthesis and characterization of endohedral fullerenes having at least one non-carbon element in the hollow fullerene cage, was started (in which about 30 atoms inserted in it so far). Furthermore, because of low efficiency and purity of these nano-particles, nowadays characterization of fullerenes is one of the most important research fields. In this project, we firstly optimized the fullerene production parameters in an arc discharge reactor to reach convenient efficiency. Then, the synthesis of endohedral fullerene by vaporizing... 

    (Synthesis and Comparative Study on Complexation of OxNy-Azacrown Macrocyclic Ligands with [60] Fullerene and Cu(II

    , M.Sc. Thesis Sharif University of Technology Varmazyad, Mahboubeh (Author) ; Ghanbari, Bahram (Supervisor)
    In our previous work in this laboratory, macrocycle containingO_2 N_2 and O_2 N_3- donor set with various ring size were synthesized. The intraction of macrocyles with [60]fullerene were determined. In this research, we synthesized 22-membered aza-crown macrocycle ligand containing O_4 N_2- donor set and characterized by NMRspectroscopy. The intraction of macrocycle with [60]fullerene were also investigated by UV-Visible spectroscopy. The formation constant was determined applying Benesi--Hildebrand equation. The result has been showed that O_4 N_2 macrocyle had better complexation with [60]fullerene in comparision of O_2 N_3 and O_2 N_2 donor sets. Then, the interaction of O_4 N_2 with... 

    Application of Pd-Au Nanoparticles on Carbon Nanotubes Modified Electrode for Electrochemical Determination of Ceftazidime

    , M.Sc. Thesis Sharif University of Technology Salimian, Razieh (Author) ; Shahrokhian, Saeed (Supervisor)
    This present work is an introduction of a new electrochemical sensor toward the determination of biomolecule. A simple electrodeposition method was employed to construct a thin film modifier of palladium–gold nanoparticles (Pd–AuNPs) decorated multi-walled carbon nanotube (MWCNT) on the surface of glassy carbon electrode (GCE). Morphological characterization of the modified electrode was performed by the scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and cyclic voltammetry (CV) techniques. This nanostructured film modified electrode effectively exhibited enhanced properties for the detection of ceftazidime (CFZ). The effects of various experimental variables such... 

    Preparation and Investigation of the Electrochemical of the Glassy Carbon Electrode Modified by Nanocellulose/Carbon Nanoparticle: Application to Pharmaceutical Determinations

    , M.Sc. Thesis Sharif University of Technology Balotf, Hamed (Author) ; Shahrokhian, Saeed (Supervisor)
    In the first part, a novel electrochemical sensor for clonazepam (CLNP) was fabricated based on immobilizing cellulose nanofibers /carbon nanoparticles (CNFs/CNPs) nanocomposite on glassy carbon electrode (CNFs/CNPs/GCE). The combination of CNFs and CNPs produced a novel kind of structurally uniform and electro-analytically active nanocomposite. The surface morphology of CNFs/CNPs layer deposited onto glassy carbon electrode was characterized by scanning electron microscopy. The results of the voltammetric investigations showed a considerable enhancement in the cathodic peak current of CLNP (up to 60 times) on the surface of CNFs/CNPs/GCE relative to the bare GCE. Under the optimal... 

    , M.Sc. Thesis Sharif University of Technology Oghbaei, Shabnam (Author) ; Ghabl, Feridon (Supervisor)
    The purpose of this study is to investigate the effect of halids on electrooxidation of silver in alkalie medium. For this case, electrochemical teqniques such as Chronoamperometery (CA) and Cyclic Voltammetry (CV) were applied. Characterization of the electrodeposition process is based on quantitative analysis of the potentiostatic current versus time curves. Rate constants of nucleation and growth obtained from the fit of the recorded transients to the generalized equations derived based on Abyaneh and Flischmann model. The conditions that justify the use of the limiting forms of the transient equations for the so-called “ instantaneous” and “ progressive” nucleation processes were... 

    Electrochemical Study on Multidentate Amino Acid Ligands and Their Co(II) and Fe(III) Complexation

    , M.Sc. Thesis Sharif University of Technology Nemati Bideh, Babak (Author) ; Ghanbari, Bahram (Supervisor)
    In our previous work, we have been undertake complexion of new amino phenolic ligand with Fe(III) and Co(II) in order to synthesis LSCF - and LSF - type perovskite inorganic membranes. In this study, the interactions between Co(II) and Fe(III) cations and the mentioned ligands were investigated their by cyclic voltammetry technique. In aqueous solution, it was found that chelate ring size has more prominent effect on the ligand-metal interaction than the related amino acid substitution. Accordingly, the amino phenol substituted... 

    Carbon paste electrode incorporating multi-walled carbon nanotube/cobalt salophen for sensitive voltammetric determination of tryptophan

    , Article Sensors and Actuators, B: Chemical ; Volume 123, Issue 2 , 2007 , Pages 942-949 ; 09254005 (ISSN) Shahrokhian, S ; Fotouhi, L ; Sharif University of Technology
    A modified carbon paste electrode is prepared by incorporating multi-walled carbon nanotube (MWCNT) and cobalt salophen (CoSal). A mixture of fine graphite powder with 10 wt% of MWCNT is applied for the preparation of carbon paste (by dispersing in Nujol) and finally modified with CoSal. The electrocatalytic oxidation of tryptophan (Trp) is investigated on the surface of the MWCNT/CoSal-modified electrode using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Using the modified electrode, the kinetics of the electro-oxidation of Trp is considerably enhanced, by lowering the anodic overpotential through a catalytic fashion. The mechanism of electrochemical behavior of Trp at... 

    A study on the kinetic of the electrodeposited Co-Ni alloy thin films in sulfate solution

    , Article Materials Chemistry and Physics ; Volume 102, Issue 2-3 , 2007 , Pages 118-124 ; 02540584 (ISSN) Dolati, A ; Sababi, M ; Nouri, E ; Ghorbani, M ; Sharif University of Technology
    The electrodeposition of cobalt, nickel and Ni-Co alloys was studied by electrochemical techniques. Cyclic voltammetry and current transient measurements were used to characterize the Co-Ni system in other to obtain the nucleation and growth mechanism. The cyclic voltammetry results clearly showed that electrodeposition of cobalt, nickel and Co-Ni alloy is diffusion-controlled process with a typical nucleation mechanism. The redox potentials of the Co and Ni are shifted to more cathodic potentials in the Co-Ni alloy system. In addition, the current transients revealed that nucleation mechanism is instantaneous with a typical three-dimensional (3D) nucleation and growth process. The number of... 

    Cobalt salophen-modified carbon-paste electrode incorporating a cationic surfactant for simultaneous voltammetric detection of ascorbic acid and dopamine

    , Article Sensors and Actuators, B: Chemical ; Volume 121, Issue 2 , 2007 , Pages 530-537 ; 09254005 (ISSN) Shahrokhian, S ; Zare Mehrjardi, H. R ; Sharif University of Technology
    A carbon-paste electrode (CPE) is modified by incorporating cobalt-5-nitrosalophen (CoNSal) and tetraoctylammonium bromide (TOAB). The mechanism of electrocatalytic oxidation of dopamine (DA) and ascorbic acid (AA) at the surface of the CoNSal-modified CPE containing various percents of TOAB is thoroughly investigated by cyclic and differential pulse voltammetry. In solutions of pH 5.0, in which all studies are performed, DA exists as the positively charged species whereas AA is mainly as the neutral form. Therefore, the favorable ionic interaction (electrostatic repulsion) between the cationic form of DA and the cationic surfactant (TOA+) caused increasing the overvoltage for DA and... 

    A kinetic study on the electrodeposition of cadmium with the presence of organic agents in sulfate solutions

    , Article Materials Chemistry and Physics ; Volume 94, Issue 1 , 2005 , Pages 23-28 ; 02540584 (ISSN) Dolati, A ; Afshar, A ; Ghasemi, H ; Sharif University of Technology
    The electrodeposition of cadmium is studied by electrochemical techniques with the presence of the organic agents. The cyclic voltammetry results clearly show that the electrodeposition of cadmium is a diffusion-controlled process associated with a typical nucleation process. With addition of the thiourea, 3-Picolin and benzyl alcohol organic agents simultaneously in sulfate solution, the redox potential of cadmium is shifted to more negative potentials. In this case, the current transients reveal an instantaneous nucleation with a typical three-dimensional (3D) growth mechanism, while it shows progressive nucleation mechanism without the ternary-species organic agents. In addition, the... 

    Synthesis, characterization, electrochemical studies and catecholase-like activity of a series of mononuclear Cu(II), homodinuclear Cu(II)Cu(II) and heterodinuclear Cu(II)Ni(II) complexes of a phenol-based compartmental ligand

    , Article Journal of Molecular Catalysis A: Chemical ; Volume 241, Issue 1-2 , 2005 , Pages 1-7 ; 13811169 (ISSN) Boghaei, D. M ; Behzad, M ; Bezaatpour, A ; Sharif University of Technology
    A series of previously reported mononuclear Cu(II) and homodinuclear Cu(II)Cu(II) complexes, as well as, novel mononuclear Cu(II), homodinuclear Cu(II)Cu(II), and heterodinuclear Cu(II)Ni(II) complexes of a phenol-based dinucleating ligand with two different N(amine)2O2 and N(imine)2O2 coordination sites, were synthesized and characterized by elemental analyses, infrared and electronic absorption spectroscopies and conductivity measurements. The electrochemical behavior and catecholase-like activity of the complexes were also studied using cyclic voltammetry and UV-vis spectrophotometry, respectively. Our results show that the dinuclear complexes are more effective catalysts in the oxidation... 

    An electrochemical study of Au-Ni alloy electrodeposition from cyanide-citrate electrolytes

    , Article Journal of Electroanalytical Chemistry ; Volume 577, Issue 1 , 2005 , Pages 1-8 ; 15726657 (ISSN) Dolati, A ; Ghorbani, M ; Ahmadi, M. R ; Sharif University of Technology
    Elsevier  2005
    Cyclic voltammetry, j-t transients and transient time measurements have been used to characterize the Au-Ni alloy deposition and to obtain the nucleation and growth mechanism. The electrodeposition of gold, nickel and gold-nickel alloys was studied in cyanide-citrate electrolytes. The analysis of the voltammograms and j-t transients clearly shows that deposition of the Au and hence, of Au-Ni alloys, is affected by adsorbed cyanide ligands mainly at low overpotentials and a direct reduction occurs at high overpotentials. In this case, the Au deposition is kinetically favored, while the Ni deposition is controlled by the cyanide-citrate adsorbed adlayer. In an alloy electrolyte, the Au and Ni... 

    Fabrication of an electrochemical sensor based on the electrodeposition of Pt nanoparticles on multiwalled carbon nanotubes film for voltammetric determination of ceftriaxone in the presence of lidocaine, assisted by factorial-based response-surface methodology

    , Article Journal of Solid State Electrochemistry ; Vol. 18, issue. 1 , 2014 , p. 77-88 Shahrokhian, S ; Hosseini-Nassab, N ; Kamalzadeh, Z ; Sharif University of Technology
    A glassy carbon electrode (GCE) is modified with platinum nanoparticle (PtNPs) decorated multiwalled carbon nanotube (MWCNT). The modified electrode is applied for the determination of ceftriaxone (CFX) in the presence of lidocaine. Different methods were used to characterize the surface morphology of the modified electrode. The electrochemical behavior of CFX was investigated at GCE, MWCNT/GCE and PtNPs/MWCNT/GCE. A factorial-based response-surface methodology was used to find out the optimum conditions with minimum number of experiments. Under the optimized conditions, oxidation peak currents increased linearly with CFX concentration in the range of 0.01-10.00 μM with a detection limit of... 

    Catalytic and antibacterial properties of 3-dentate carboxamide Pd/Pt complexes obtained via a benign route

    , Article Applied Organometallic Chemistry ; Volume 34, Issue 4 , April , 2020 Kiani, M ; Bagherzadeh, M ; Meghdadi, S ; Fadaei Tirani, F ; Schenk Joß, K ; Rabiee, N ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    The complexes PdII(qcq)(OAc) and PtII(qcq)Cl have been synthesized using environmentally benign synthesized ligands and characterized by elemental analyses: Fourier transform infrared spectroscopy, UV–visible spectroscopy, 1H NMR spectroscopy, and X-ray diffraction. The catalytic activity of the complex was assessed, in different media, for the Mizoroki–Heck coupling reaction for typical aryl halides and terminal olefins under aerobic conditions. Since the base and the solvent were found to influence the efficiency of the reaction, reaction conditions, temperature, time, and the amount of K3PO4 and a mixture of H2O/PEG, were optimized. We found, for the Mizoroki–Heck reaction coupling less... 

    Simultaneous Voltammetric Determination of Epinephrine and UricAcid in Presence of Ascorbic Acid Using Pyrolytic Graphite Electrode Modified with Nano- diamond/graphite Film & Voltammetric Determination of Levothyroxine at the Surface of Edge Plane Pyrolytic Graphite Electrode

    , M.Sc. Thesis Sharif University of Technology Khafaji, Mona (Author) ; Shahrokhian, Saeed (Supervisor)
    Part 1: A novel modified pyrolytic graphite electrode with nanodiamond/graphite was fabricated. The electrochemical response characteristics of the modified electrode toward the epinephrine (EN) and uric acid (UA) are studied by means of cyclic and linear sweep voltammetry. The structural morphology and thickness of the film was characterized by SEM technique.The prepared electrode shows an excellent catalytic activity in the electrochemical oxidation of EN and UA, leading to remarkable enhancements in the corresponding peak currents and lowering the peak potentials. The prepared modified electrode acts as a highly sensitive sensor for simultaneous determination of EN and UA in the presence... 

    Synthesis of Gold Nanoparticles and Study on Their Applications as a Catalyst and as a Carrier for the Radiomedicines

    , M.Sc. Thesis Sharif University of Technology Eskandari, Najmeh (Author) ; Outokesh, Mohammad (Supervisor) ; Ahmadi, Javad (Supervisor) ; Sadjadi, Soude (Co-Advisor)
    This thesis encompasses two parallel, but independent subjects as follow: The first part of the thesis deals with synthesis of bimetallic Ni-Au nanoparticles (Bi Ni-Au), and application of them as electrodes in the methanol fuel cells. The Bi Ni-Au nanoparticles for this purpose were synthesized by controlled reduction of HAuCl3 and NiCl3 in the aqueous medium using NaBH4 as reductant and PVP as stabilizer, and immobilized on the surface of a glassy carbon (GC) electrode by means of Nafion polymer. The obtained electrode then was conditioned in an alkaline solution by cyclic voltammetric method in potential range 100 -700 mV (vs. Ag/AgCl). Physicochemical characterizations of the... 

    Probing the Electrochemical Properties of Gold Electrode Modified with Edge-Functionalized Graphene and its Application

    , M.Sc. Thesis Sharif University of Technology Aghajani, Talin (Author) ; Shahrokhian, Saeed (Supervisor)
    In the present work, edge-functionalaized graphene was used as electrode material and its electrochemical properties were systematically characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Two methods were applied to modify the gold electrode surface. First method was the self assembling process of graphene nanosheets on gold electrode surface. Second method was simply casting specific amounts of graphene suspension on the gold electrode surface. Nyquist plots show decrease of the charge transfer resistance on the electrode surface at both cases. In cyclic voltammetry studies, first electrode shows no significant changes while the second electrode exhibits...