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    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 Moravvej, Heydar (Author) ; Taherinia, Davood (Supervisor)
    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... 

    Corrosion resistance enhancement of Ni-P-nano SiO2 composite coatings on aluminum

    , Article Applied Surface Science ; Vol. 303 , 2014 , Pages 125-130 ; ISSN: 01694332 Sadreddini, S ; Afshar, A ; Sharif University of Technology
    In this study, the influences of different concentrations of SiO 2 nano sized particles in the bath on deposition rate, surface morphology and corrosion behavior of Ni-P-SiO2 Composite coatings were investigated. The deposition rate of coating was influenced by incorporation of SiO2 particles. The microstructure was investigated with field emission scanning electron microscopy (FESEM). The amount of SiO 2 was examined by Energy Dispersive Analysis of X-Ray (EDX) and amount of SiO2 nanoparticles co-deposited reached a maximum value at 4.5 %wt. Corrosion behavior of coated aluminum was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results... 

    Graphene/PbS as a novel counter electrode for quantum dot sensitized solar cells

    , Article ACS Photonics ; Vol. 1, issue. 4 , March , 2014 , pp. 323-330 ; ISSN: 23304022 Parand, P ; Samadpour, M ; Esfandiar, A ; Iraji Zad, A ; Sharif University of Technology
    PbS nanoparticles were in situ deposited on graphene sheets by a successive ionic liquid adsorption and reaction method to prepare a graphene/PbS composite counter electrode for CdS/CdSe quantum dot sensitized solar cells (QDSCs). Under 1 sun illumination, the cells with graphene/PbS counter electrodes (CEs) show a maximum energy conversion efficiency of 2.63%, which is remarkably higher than that of those employing PbS (1.28%) or graphene (0.23%) CEs. Electrochemical impedance spectroscopy analysis shows that graphene/PbS composite counter electrodes have lower charge-transfer resistance at the interface of the CE and the polysulfide redox electrolyte, compared to those cells with PbS and... 

    Electrochemical synthesis of reduced graphene oxide/TiO2 nanotubes/Ti for high-performance supercapacitors

    , Article Ionics ; Volume 21, Issue 2 , 2014 , Pages 525-531 ; ISSN: 09477047 Gobal, F ; Faraji, M ; Sharif University of Technology
    RGO/TiO2NTs/Ti electrodes with high surface area and good capacitive characteristics were prepared by simple electrochemical reduction of graphene oxide (GO) onto the previously formed TiO2 nanotubes. Microstructure studies show that reduced graphene oxide (RGO) having high surface area has been deposited onto the TiO2NT arrays. The electrochemical capacitive behaviors of the obtained electrodes were investigated by cyclic voltammetry (CV), galvanostatic charge–discharge studies, and electrochemical impedance spectroscopy (EIS) in 1 M H2SO4 solution. The electrochemical data demonstrated that the electrodes displayed specific capacitance of 410 F g−1 at the current density of 50 A g−1 and... 

    Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors

    , Article Applied Physics A: Materials Science and Processing ; Vol. 117, issue. 4 , 2014 , pp. 2087-2094 ; ISSN: 09478396 Gobal, F ; Faraji, M ; Sharif University of Technology
    Nanoporous/cracked structures of cobalt oxide (Co3O4) electrodes were successfully fabricated by electroplating of zinc–cobalt onto previously formed TiO2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400 °C. The structure and morphology of the obtained Co3O4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co3O4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co3O4 electrodes were investigated by cyclic... 

    Study of the alloying additives and alkaline zincate solution effects on the commercial aluminum as galvanic anode for use in alkaline batteries

    , Article Materials Chemistry and Physics ; Volume 143, Issue 1 , 2013 , Pages 133-142 ; ISSN: 02540584 Rashvand Avei, M ; Jafarian, M ; Moghanni Bavil Olyaei, H ; Gobal, F ; Hosseini, S. M ; Mahjani, M. G ; Sharif University of Technology
    The corrosion behavior of different grades of commercial aluminum such as AA1040, AA5083, AA6060 and AA7075 in ZnO-containing 4 M NaOH has been determined by using open circuit potential-time measurements (OCP), galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) reveal that ZnO produces the inhibition effect by the formation of a zinc-containing deposit layer on the surface of aluminum electrodes. Although the influence of zincating on the performance of aluminum alloys and considering the amount of alloying elements such as zinc, magnesium and... 

    Electropolishing effect on corrosion resistance of electrodeposited nanocrystalline Ni-Mo alloy coatings in NaCl solution

    , Article ECS Transactions ; Volume 45, Issue 19 , 2013 , Pages 65-76 ; 19385862 (ISSN) ; 9781623320355 (ISBN) Roozbehani, B ; Allahyarzadeh, M. H ; Ashrafi, A ; Shadizadeh, S. R ; Seddighian, A ; Sharif University of Technology
    The aim of current research is to investigate the substrate electropolishing effect on corrosion resistance of Ni-Mo thin films. For this purpose, corrosion resistance of coatings deposited on mild steel substrates, that was electropolished or mechanically polished, have been compared in 3.5 wt.% NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The structural properties of Ni-Mo thin films were evaluated using X-ray diffraction (XRD) and their morphology, microstructure and chemical composition were also investigated using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). Temperature and acidity of deposition... 

    The improvement of electron transport rate of TiO2 dye-sensitized solar cells using mixed nanostructures with different phase compositions

    , Article Ceramics International ; Volume 39, Issue 7 , 2013 , Pages 7343-7353 ; 02728842 (ISSN) Bakhshayesh, A. M ; Mohammadi, M. R ; Sharif University of Technology
    Dye-sensitized solar cells (DSCCs) in the form of mixed nanostructures containing TiO2 nanoparticles and nanowires with different weight ratios and phase compositions are reported. X-ray diffraction and field emission scanning electron microscopy analyses revealed that the synthesized TiO 2 nanoparticles had average crystallite size in the range 21-39 nm, whereas TiO2 nanowires showed diameter in the range 20-50 nm. The indirect optical band gap energy of TiO2 nanowires, anatase- and rutile-TiO2 nanoparticles was calculated to be 3.35, 3.28 and 3.17 eV, respectively. The power conversion efficiency of the solar cells changed with nanowire to nanoparticle weight ratio, reaching a maximum at a... 

    Effect of pH and carbon nanotube content on the corrosion behavior of electrophoretically deposited chitosan-hydroxyapatite-carbon nanotube composite coatings

    , Article Ceramics International ; Volume 39, Issue 5 , July , 2013 , Pages 5393-5402 ; 02728842 (ISSN) Batmanghelich, F ; Ghorbani, M ; Sharif University of Technology
    In the first stage, chitosan (CH)-hydroxyapatite (HA)-multiwalled carbon nanotube (MWCNT) composite coatings were synthesized by electrophoretic deposition technique (EPD) on 316L stainless steel substrates at different levels of pH and characterized by X-ray diffraction (XRD), Raman spectroscopy, FTIR and field emission scanning electron microscopy (FESEM). A smooth distribution of HA and MWCNT particles in a chitosan matrix with strong interfacial bonding was obtained. In the next stage, effects of pH and MWCNT content of the suspension on the corrosion behavior and deposition mechanism were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) curves... 

    Fabrication of nanoporous nickel oxide by de-zincification of Zn-Ni/(TiO2-nanotubes) for use in electrochemical supercapacitors

    , Article Electrochimica Acta ; Volume 100 , 2013 , Pages 133-139 ; 00134686 (ISSN) Gobal, F ; Faraji, M ; Sharif University of Technology
    NiO-ZnO/TiO2NTs electrodes were synthesized by the electrodeposition of Zn-Ni onto TiO2 nanotubes, dealloying in a concentrated alkaline solution and finally calcination of the resulting Zn(OH)2-Ni(OH)2/TiO2NTs at 300 C. Morphology of the electrodeposited nanostructures was studied using scanning electron microscopy (SEM) while their electrochemical characterizations were carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge procedures. The SEM analysis revealed the nanoporous/cracked structures of the NiO-ZnO/TiO2NTs obtained at the electroplating time of 20 min. The EIS studies showed that nanoporous/cracked structures of... 

    Construction of a modified carbon paste electrode based on TiO2 nanoparticles for the determination of gallic acid

    , Article Journal of Solid State Electrochemistry ; Volume 17, Issue 1 , 2013 , Pages 157-165 ; 14328488 (ISSN) Tashkhourian, J ; Nami Ana, S. F ; Hashemnia, S ; Hormozi Nezhad, M. R ; Sharif University of Technology
    A modified carbon paste electrode was prepared by incorporating the TiO2 nanoparticles in the carbon paste matrix. The electrochemical behavior of gallic acid (GA) is investigated on the surface of the electrode using cyclic voltammetry and differential pulse voltammetry. The surface morphology of the prepared electrode was characterized using the scanning electron microscopy. The results indicate that the electrochemical response of GA is improved significantly at the modified electrode compared with the unmodified electrode. Furthermore, the capabilities of electron transfer on these two electrodes were also investigated by electrochemical impedance spectroscopy. Under the optimized... 

    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) Salehi Doolabi, D ; Ehteshamzadeh, M ; Mirhosseini, S. M. M ; Sharif University of Technology
    Springer  2012
    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... 

    A comparative study of sequentially layer-deposited and co-deposited Co-Mn oxides as potential redox capacitors

    , Article Journal of Solid State Electrochemistry ; Volume 16, Issue 4 , April , 2012 , Pages 1561-1569 ; 14328488 (ISSN) Gobal, F ; Jafarzadeh, S ; Sharif University of Technology
    Layers of cobalt and manganese oxides were co-deposited or deposited on top of each other or next to each other by potentiostatic method onto stainless steel substrate. Deposition potentials of 1 and -1 V for the anodic and cathodic depositions were employed. Specific capacitance values in the range of 38.5-78 F g -1 were found with cobalt oxide on top of manganese oxide having the lowest and manganese oxide on top of cobalt oxide having the highest capacitances. The usefulness of the electrodes was characterized by cyclic voltammetry, charge-discharge cycling, and electrochemical impedance spectroscopy in 2 M NaOH electrolyte for redox supercapacitor applications. The latter presented the... 

    Polysulfide poisoning of Ag electrocatalyst during L-ascorbate ion electro-oxidation in alkaline solution

    , Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 33, Issue 2 , 2012 , Pages 267-274 ; 02539837 (ISSN) Gobal, F ; Majari Kasmaee, L ; Sharif University of Technology
    L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10 -5 to 4.5 × 10 -4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy. Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation, with the poisoning effect of polysulfide ion being more pronounced in the potential range of -0.3 to -0.2 V/SCE. The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were, 10 -3 to 1 × 10 -2 s and 1 × 10 -4 to 1 × 10 -2 s, respectively depending on the potential used for the impedance analysis. Based on the cyclic... 

    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) Jafarian, M ; Haghighatbin, M. A ; Gobal, F ; Mahjani, M. G ; Rayati, S ; Sharif University of Technology
    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... 

    Enhanced corrosion resistance of porous NiTi with plasma sprayed alumina coating

    , Article Corrosion Engineering Science and Technology ; Volume 50, Issue 8 , 2015 , Pages 595-600 ; 1478422X (ISSN) Hosseini, S. A ; Akbarinia, S ; Mohammadyani, D ; Sadrnezhaad, S. K ; Sharif University of Technology
    Maney Publishing  2015
    In this study, corrosion behaviour of porous NiTi modified by plasma sprayed alumina coating has been investigated. Scanning electron microscopy and X-ray diffraction techniques were applied for the morphology and microstructure characterisation, while linear sweep voltammetry and electrochemical impedance spectroscopy were used for investigation of corrosion behaviour of coated and uncoated NiTi specimens. Induced couple plasma was conducted to measure ion release of the specimens in simulated body fluid at 37°C. The plasma sprayed Al2O3 coating on the porous NiTi improved the surface characteristics for biomedical applications. The alumina coating significantly hampered Ni ion release from... 

    Effects of alumina nanoparticles concentration on microstructure and corrosion behavior of coatings formed on titanium substrate via PEO process

    , Article Ceramics International ; Volume 42, Issue 7 , May , 2016 , Pages 8789–8797 ; 02728842 (ISSN) Sarbishei, S ; Faghihi Sani, M. A ; Mohammadi, M. R ; Sharif University of Technology
    Elsevier Ltd  2016
    Plasma electrolytic oxidation (PEO) process was employed to create ceramic coatings on titanium substrate by using silicate-based electrolytes containing different concentrations of alumina nanoparticles (0, 3, 6, and 10. g/lit). The effect of alumina nanoparticles concentration on the morphology, chemical and phase composition of the PEO coatings was investigated by scanning electron microscope, energy dispersive spectrometer, and X-ray diffractometer, respectively.The corrosion behavior of samples was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. SEM, EDS, and XRD analyses illustrated that alumina nanoparticles incorporated into the... 

    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... 

    The influence of surface nanocrystallization induced by shot peening on corrosion behavior of niti alloy

    , Article Journal of Materials Engineering and Performance ; Volume 24, Issue 8 , August , 2015 , Pages 3093-3099 ; 10599495 (ISSN) Olumi, S ; Sadrnezhaad, S. K ; Atai, M ; Sharif University of Technology
    Springer New York LLC  2015
    Nickel-titanium (NiTi) shape memory alloys have been widely used as implant materials, due to their superior shape memory properties and similar mechanical behavior to bone tissue. The presence of nickel on the surface of nickel-titanium alloy and release of this ion in the body environment will result in some allergic reactions. In current study, we used shot pinning process to produce nanocrystalline nickel-titanium alloy with increased corrosion resistance. Field emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD) analysis, and atomic force microscopy were employed to investigate the surface features of samples. The quantitative chemical analysis of NiTi and modified... 

    Enhanced dye loading-light harvesting TiO2 photoanode with screen printed nanorod-nanoparticles assembly for highly efficient solar cell

    , Article Electrochimica Acta ; Volume 169 , 2015 , Pages 395-401 ; 00134686 (ISSN) Jalali, M ; Siavash Moakhar, R ; Kushwaha, A ; Goh, G. K. L ; Riahi-Noori, N ; Sadrnezhaad, S. K ; Sharif University of Technology
    Elsevier Ltd  2015
    Morphology tailored TiO2 nano assemblies consisting of nanorods with and without nanoparticle attachments were hydrothermally synthesized and their characteristics and light scattering properties were determined by x-ray diffraction (XRD), nitrogen sorption analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and ultraviolet-visible spectroscopy (UV-Vis). The nanorod-nanoparticles (NR-NP) assemblies and smooth nanorod (NR) double layers were screen printed onto fluorine doped tin oxide coated glass underlayers to fabricate dye-sensitized solar cell (DSSC) photoanodes. The double layer heterogeneous...