Search for: electrocatalytic-activity
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    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) Jafarian, M ; Azizi, O ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    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... 

    Morphology-Dependent Electrocatalytic Activity of Silver Nanostructures and Differentia Pulse Voltammetry Determination of Atorvastatin at Silver Nanowires Modified Electrode

    , M.Sc. Thesis Sharif University of Technology Naseri, Amene (Author) ; Shahrokhian, Saeed (Supervisor) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    In this work two shapes of silver nanostructures including silver nanowires and silver nanocubeswere synthesized by polyol method. Silver nanostructures were characterized by SEM, XRD and UV-Vis spectroscopy. Afterwards the morphology-dependent electrocatalyticperformance of these nanocrystals on the differential pulse behavior of naltrexone (NAL) was investigated. To this aim the differential pulse voltammetric behavior of NAL on a glassy carbon electrode modified with electrochemical deposited gold nanoparticles conjugated with different shapes of silver nanostructures and nafion was investigated. It was proved that silver nanowires show more effective electrocatalytic activity toward... 

    Electrochemical Properties and Stability of Ruddlesden-Popper (RP) Nickelates as Cathodes for IT-SOFC

    , Ph.D. Dissertation Sharif University of Technology Khoshkalam, Mohammad (Author) ; Faghihi Sani, Mohammad Ali (Supervisor) ; Madaah Hosseini, Hamid Reza (Co-Supervisor)
    For improving cost competitiveness of both SOEC and SOFC technology, it is desirable to reduce the temperature of operation preferably down towards 500 oC – 600 oC, as this will slow down the rate of various degradation processes and allow use of much cheaper materials for auxiliary components. In this range, the oxygen electrode typically dominates the cell resistance, and hence there is a need to develop cost effective electrodes with improved performance at low temperature. Whereas the oxygen exchange on Ruddlesden-Popper type Ni based compounds like Pr2NiO4 with interstitial oxygen defects is known to be very fast, reported electrode performance of micron-sized composites based on these... 

    Synthesis and Characterization of Graphene-based Cathode Performance for Lithium Battery

    , M.Sc. Thesis Sharif University of Technology Ghorbani, Younes (Author) ; Dolati, Abolghasem (Supervisor)
    The air cathode of li-air batteries plays a pivotal role in the overall performance of Li-air batteries. Graphene-based cathodes have been investigated as cathode catalysts for lithium-air batteries due to their extraordinary potential for accelerating and facilitating oxygen reduction reaction (ORR).In this study graphene oxide have been synthesized via modified Hummers’ method. Consequently, the as obtained graphene oxide have been reduced using chemical, electrochemical, and hydrothermal methods. Results of elechtrochemical evaluations demonstrate that the graphene oxide reduced via hydrothermal method possesses the most positive ORR onset potential (+0.55V vs SHE) among the other samples... 

    Modification of well-aligned carbon nanotubes with dihexadecyl hydrogen phosphate: Application to highly sensitive nanomolar detection of simvastatin

    , Article Journal of Applied Electrochemistry ; Volume 44, Issue 2 , February , 2014 , Pages 263-277 ; ISSN: 0021891X Fayazfar, H ; Afshar, A ; Dolati, A ; Ghalkhani, M ; Sharif University of Technology
    The first usage of dihexadecyl hydrogen phosphate (DHP)-modified highly oriented multi-walled carbon nanotube (MWCNTs) forests in a sensor configuration was developed to investigate the electrochemical oxidation and determination of simvastatin (SV) in pharmaceutical dosage forms. Synthesis of well-aligned MWCNTs on a conductive Ta substrate by catalytic vapor deposition technique using a common chemical, ethylenediamine, and without being plasma-aided was reported. The electrochemical behavior and oxidation of SV at the aligned MWCNTs/DHP/Ta electrode were discussed in detail through cyclic voltammetry and differential pulse voltammetry. This modified electrode showed considerably higher... 

    A comparative study of the electrooxidation of ethylene glycol on transition metal electrodes in alkaline solution

    , Article Journal of New Materials for Electrochemical Systems ; Volume 15, Issue 4 , 2012 , Pages 255-263 ; 14802422 (ISSN) Danaee, I ; Jafarian, M ; Shahnazi Sangachin, A. A ; Gobal, F ; Sharif University of Technology
    Electrodes made of group VIII and IB metals were examined for their redox process and electrocatalytic activities towards the oxidation of ethylene glycol in alkaline solutions. The method of cyclic voltammetery (CV) and Open circuit potentials measurement (OCP) was employed. It is found that considerable electrooxidation current are observed for silver and copper but lower anodic overpotential for oxidation is obtained for gold and platinum. Oxide layer produced on the surface of all electrodes in alkaline solution under anodic scan participates in ethylene glycol electrooxidation. Oxidation current observed in the reverse scans for platinum and gold are higher than those observed in... 

    Electrochemical sensing based on carbon nanoparticles: A review

    , Article Sensors and Actuators, B: Chemical ; Volume 293 , 2019 , Pages 183-209 ; 09254005 (ISSN) Asadian, E ; Ghalkhani, M ; Shahrokhian, S ; Sharif University of Technology
    Elsevier B.V  2019
    The emergence of nanoscience and nanotechnology has opened up new horizons to researchers. In this regard, carbon nanomaterials are considered as the cornerstone of numerous investigations. Among various carbon nanostructures, “Carbon nanoparticles (CNPs)” have attracted a great deal of attention during the past few years due to their unique properties such as high surface area, non-toxicity, biocompatibility as well as simple and low-cost synthetic procedures via environmentally friendly routes. Thanks to these properties along with their interesting optical behavior, CNPs have found diverse applications in the fields of bioimaging, nanomedicine, photo/electro-catalysis, and bio/chemical... 

    Review - Towards the two-dimensional hexagonal boron nitride (2D h-BN) electrochemical sensing platforms

    , Article Journal of the Electrochemical Society ; Volume 167, Issue 12 , 2020 Angizi, S ; Khalaj, M ; Alem, S. A. A ; Pakdel, A ; Willander, M ; Hatamie, A ; Simchi, A ; Sharif University of Technology
    IOP Publishing Ltd  2020
    Electrochemical sensing performance of two-dimensional hexagonal boron nitride (2D h-BN) has traditionally been suppressed by their intrinsic electrical insulation and deficient electron transportation mechanism. However, the excellent electrocatalytic activity, high specific surface area, N- and B-active edges, structural defects, adjustable band gap through interaction with other nanomaterials, and chemical functionalization, makes 2D h-BN ideal for many sensing applications. Therefore, finding a pathway to modulate the electronic properties of 2D h-BN while the intrinsic characteristics are well preserved, will evolve a new generation of highly sensitive and selective electrochemical... 

    Enhanced Activity of Pr6O11 and CuO Infiltrated Ce0.9Gd0.1O2 Based Composite Oxygen Electrodes

    , Article Journal of the Electrochemical Society ; Volume 167, Issue 2 , January , 2020 Khoshkalam, M ; Faghihi Sani, M. A ; Tong, X ; Chen, M ; Hendriksen, P. V ; Sharif University of Technology
    Institute of Physics Publishing  2020
    Operation of solid oxide fuel/electrolysis cells (SOFC/SOEC) at high temperatures (T > 850 °C) is accompanied by degradation phenomena, which severely affect the operational lifetime of the cell. Degradation processes are expected to occur slower at low temperatures. However, significant reduction in electrocatalytic activity of the oxygen electrode, is one of the major challenges in decreasing the operating temperature down to 500 °C-650 °C. Recently, Pr6O11 infiltrated Ce0.9Gd0.1O2 (CGO) based electrodes have been proposed to realize high electrochemical performance at intermediate temperature. In this study, Pr-oxide has been infiltrated into a well performing sub-micro... 

    Template-based electrodeposition of Pt/Ni nanowires and its catalytic activity towards glucose oxidation

    , Article Electrochimica Acta ; Volume 58, Issue 1 , 2011 , Pages 551-555 ; 00134686 (ISSN) Mahshid, S. S ; Mahshid, S ; Dolati, A ; Ghorbani, M ; Yang, L ; Luo, S ; Cai, Q ; Sharif University of Technology
    An electro-catalysis non-enzymatic electrode is proposed based on alloyed Pt/Ni nanowire arrays (NWAs) for the detection of glucose. The Pt/Ni NWAs were prepared by pulse electrodeposition of Pt and Ni within a nano-pore polycarbonate (PC) membrane followed by a chemical etching of the membrane. The electrode structure is characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resulting Pt/Ni NWAs electrode shows high electrocatalytic activities towards the oxidation of glucose in alkaline solution. Consequently, a sensitive amperometric detection of glucose is achieved under 0.45 V vs. SCE with a low detection limit of 1.5 μM within a wide linear... 

    RuO2/MWCNT/ stainless steel mesh as a novel positive electrode in vanadium redox flow batteries

    , Article RSC Advances ; Volume 5, Issue 84 , Aug , 2015 , Pages 68378-68384 ; 20462069 (ISSN) Gobal, F ; Faraji, M ; Sharif University of Technology
    Royal Society of Chemistry  2015
    The present work describes the preparation and electrochemical characterization of RuO2/MWCNT/Stainless Steel Mesh (SSM) electrode as compared with a MWCNT/SSM electrode in the positive half-cell of a Vanadium Redox Flow Battery (VRFB). The electrochemical characterization of prepared electrode was carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge procedures. The electrochemical activity of MWCNT/SSM modified with RuO2 as positive electrode in a VRFB was notably improved. The RuO2-included electrodes demonstrated high peak current ratio, small peak potential difference and high electron... 

    A kinetic study on the electrodeposition of nickel nanostructure and its electrocatalytic activity for hydrogen evolution reaction

    , Article Journal of Applied Electrochemistry ; Volume 40, Issue 11 , November , 2010 , Pages 1941-1947 ; 0021891X (ISSN) Torabi, M ; Dolati, A ; Sharif University of Technology
    The electrodeposition of nickel was studied using electrochemical techniques in different electrolytes and various agents. The voltammetry analysis clearly showed that the electrodeposition of nickel was a diffusion-controlled process associated with a typical nucleation process. The current transients represented instantaneous nucleation with a typical three-dimensional (3D) growth mechanism. Scharifker's equations were derived for instantaneous and progressive nucleation of the 3D growth of the spherical centers under diffusion-controlled condition. The number of nucleation sites increased with the increment in overpotential and Ni 2+ concentration. Atomic force microscopy was used to... 

    A preliminary study of the electro-catalytic reduction of oxygen on Cu-Pd alloys in alkaline solution

    , Article Journal of Electroanalytical Chemistry ; Volume 647, Issue 1 , 2010 , Pages 66-73 ; 15726657 (ISSN) Gobal, F ; Arab, R ; Sharif University of Technology
    Copper-palladium alloys of different compositions are electrodeposited on nickel from aqueous solutions. These alloys are characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The catalytic activity of these alloys toward oxygen reduction reaction (ORR) in alkaline solution is investigated using rotating disk electrode (RDE). The number of electrons transferred per O2 molecule (n) obtained at different potentials is close to 2 at low overpotential indicating HO2- formation and gradually increases to 4 at higher overpotentials indicating full reduction to OH-. It is shown that Cu-Pd alloys are better electrocatalysts than Pd with Pd-Cu-1 having 24.5%... 

    Selective voltammetric determination of d-penicillamine in the presence of tryptophan at a modified carbon paste electrode incorporating TiO2 nanoparticles and quinizarine

    , Article Journal of Electroanalytical Chemistry ; Volume 644, Issue 1 , Jan , 2010 , Pages 1-6 ; 15726657 (ISSN) Mazloum Ardakani, M ; Beitollahi, H ; Taleat, Z ; Naeimi, H ; Taghavinia, N ; Sharif University of Technology
    A carbon paste electrode (CPE) chemically modified with TiO2 nanoparticles and quinizarine (QZ) was used as a selective electrochemical sensor for the simultaneous determination of minor amounts of d-penicillamine (D-PA) and tryptophan (Trp). This modified electrode showed very efficient electrocatalytic activity for anodic oxidation of both d-PA and Trp. Substantial decreases of anodic overpotentials for both compounds made this analysis possible. Results of square wave voltammetry (SWV) using this modified electrode showed two well-resolved anodic waves for the oxidation of d-PA and Trp, which makes the simultaneous determination of both compounds possible. The peak potential for the... 

    Nanostructured silver fibers: Facile synthesis based on natural cellulose and application to graphite composite electrode for oxygen reduction

    , Article International Journal of Hydrogen Energy ; Volume 35, Issue 8 , 2010 , Pages 3258-3262 ; 03603199 (ISSN) Sharifi, N ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
    The development of cheaper electrocatalysts for fuel cells is an important research area. This work proposes a new, simpler and low-cost approach to develop nanostructured silver electrocatalysts by using natural cellulose as a template. Silver was deposited by reduction of Ag complexes on the surface of cellulose fibers, followed by heat removal of the template to create self-standing nanostructured silver fibers (NSSFs). X-Ray diffraction (XRD) showed fcc silver phase and X-Ray photoelectron spectroscopy (XPS) demonstrated that the surface was partially oxidized. The morphology of the fibers consisted of 50 nm nanoparticles as the building blocks, and they possessed a specific surface area... 

    Zinc oxide/copper sulfide nanorods as a highly catalytic counter electrode material for quantum dot sensitized solar cells

    , Article RSC Advances ; Volume 6, Issue 57 , 2016 , Pages 51894-51899 ; 20462069 (ISSN) Eskandari, M ; Ghahary, R ; Shokri, M ; Ahmadi, V ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Copper sulfide deposited ZnO nanorods (ZnO NRs/CuS) have been applied as a new counter electrode material with high electrocatalytic activity towards polysulfide electrolyte, which results in the formation of a highly efficient counter electrode for QDSSCs. It was observed from the current density-voltage (J-V) characteristics that the short-circuit current density (Jsc), power conversion efficiency (PCE), and fill factor (FF) were enhanced from 7.63 mA cm-2 to 14.48 mA cm-2, 1.59% to 4.18%, and 0.29 to 0.38, respectively, when a bare CuS counter electrode was changed to a ZnO NRs/CuS counter electrode. Electrochemical impedance spectroscopy (EIS), Tafel polarization and cyclic voltammetry... 

    Electrochemical investigation of electrodeposited platinum nanoparticles on multi walled carbon nanotubes for methanol electro-oxidation

    , Article Journal of Chemical Sciences ; Volume 129, Issue 9 , 2017 , Pages 1399-1410 ; 09743626 (ISSN) Mokarami Ghartavol, H ; Moakhar, R. S ; Dolati, A ; Sharif University of Technology
    Abstract: The electrodeposition of platinum nanoparticles (PtNPs) on multiwall carbon nanotubes (MWCNTs)/fluorine-doped tin oxide glass (FTO) was investigated. Nucleation and growth mechanisms were studied via Scharifker and Hills model. Chronoamperometry results clearly show that the electrodeposition processes are diffusion-controlled and the diffusion coefficient is 1.5×10-5cm2/s. The semi-spherical particles with lamellar morphology were observed in 1M H 2SO 4, while a petal shape was discerned in 0.5M H 2SO 4. Also, dispersion, size, and uniformity of PtNPs were investigated, where the finer distribution of PtNPs with the average size less than 100 nm was obtained in 0.5M H 2SO 4... 

    Microstructure, morphology and electrochemical properties of Co nanoflake water oxidation electrocatalyst at micro- and nanoscale

    , Article RSC Advances ; Volume 7, Issue 21 , 2017 , Pages 12923-12930 ; 20462069 (ISSN) Naseri, N ; Solaymani, S ; Ghaderi, A ; Bramowicz, M ; Kulesza, S ; Ţălu, Ş ; Pourreza, M ; Ghasemi, S ; Sharif University of Technology
    Royal Society of Chemistry  2017
    Nowadays, fossil fuel limitations and environmental concerns push researchers to find clean and renewable energy resources. Solar hydrogen production via water splitting reactions in electrochemical and/or photo-electrochemical systems has been accepted as a promising route and efficient electrocatalysts are involved in both. Here, cobalt nanoflakes with an oxide/hydroxide surface and a conductive metallic core are grown on commercially available steel mesh modified with carbon based nanocomposites as a support layer. The portion of reduced graphene oxide sheets was changed from 0 to 100 wt% and the correlation of this concentration with the surface morphology and electro-catalytic activity... 

    Mechanochemical green synthesis of exfoliated edge-functionalized boron nitride quantum dots: application to vitamin c sensing through hybridization with gold electrodes

    , Article ACS Applied Materials and Interfaces ; Volume 10, Issue 34 , 2018 , Pages 28819-28827 ; 19448244 (ISSN) Angizi, S ; Hatamie, A ; Ghanbari, H ; Simchi, A ; Sharif University of Technology
    American Chemical Society  2018
    Two-dimensional boron nitride quantum dots (2D BNQDs) with excellent chemical stability, high photoluminescence efficiency, and low toxicity are a new class of advanced materials for biosensing and bioimaging applications. To overcome the current challenge about the lack of facile, scalable, and reproducible synthesis approach of BNQDs, we introduce a green and facile approach based on mechanochemical exfoliation of bulk h-BN particles in ethanol. Few-layered hydroxylated-functionalized QDs with a thickness of 1-2 nm and a lateral dimension of 2-6 nm have been prepared. The synthesized nanocrystals exhibit a strong fluorescence emission at 407 and 425 nm with a quantum efficiency of ∼6.2%.... 

    Yttrium hexacyanoferrate microflowers on freestanding three-dimensional graphene substrates for ascorbic acid detection

    , Article ACS Applied Nano Materials ; Volume 2, Issue 4 , 2019 , Pages 2212-2221 ; 25740970 (ISSN) Hatamie, A ; Rahmati, R ; Rezvani, E ; Angizi, S ; Simchi, A ; Sharif University of Technology
    American Chemical Society  2019
    Recently, three-dimensional carbon nanostructures have attracted significant attention for biosensing applications. We have prepared highly porous three-dimensional graphene (3DG) structures (90% porosity) by template-assisted chemical vapor deposition technique and enhanced their electrocatalytic activity through in situ electrochemical deposition of rose-like yttrium hexacyanoferrate particles on their struts. The 3DG structure has an average channel size of ∼500 μm, and the microflowers have lateral sizes in the range of 2-10 μm. The performance of the 3DG-based electrode in efficient detection of ascorbic acid was investigated after transferring on a gold screen printed electrode (SPE)....