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    Carbon nanotubes/alizarin red S-poly(vinylferrocene) modified glassy carbon electrode for selective determination of dopamine in the presence of ascorbic acid
    (Springer, 2012) Sen, Mine; Tamer, Ugur; Pekmez, Nuran Ozcicek
    A modified electrode was fabricated by electrochemical formation of poly(vinylferrocene) on the multiwall carbon nanotube-alizarin red S matrix covered glassy carbon electrode. A higher electrochemical activity was obtained to the electrocatalytic oxidation of dopamine. The electrode surface was characterized electrochemically and spectroscopically. Poly(vinylferrocene) (PVF) in electrode was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. Multi-wall carbon nanotubes (MWCNTs) / alizarin red S (ARS)-PVF electrode was used to the determination of dopamine in the presence of ascorbic acid in 0.1 M sulphate buffer solution at pH 7. The performance of the MWCNTs/ARS-PVF electrode was evaluated by DPV and amperometry.
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    ELECTROCHEMICAL PREPARATION OF POLY(VINYLFERROCENIUM)-PERCHLORATE-POLYANILINE COMPOSITE-MODIFIED PLATINIUM ELECTRODE IN METHYLENE CHLORIDE
    (Inst Organic Chem And Biochem, 2011) Kavanoz, Muammer; Sen, Mine; Pekmez, Nuran Ozcicek
    A new surface based on poly(vinylferrocenium) perchlorate-polyaniline (PVF+ClO4 -PANI) composite-modified platinum electrode was prepared electrochemically to combine the electrocatalytic properties of an intrinsically conducting polymer and a redox polymer. The composite film was synthesized as a bilayer from individual polymerization solutions. Furthermore, PVF+ClO4- and PANI polymers were simultaneously deposited as a mixture from a methylene chloride solution containing PVF polymer and aniline monomer on Pt electrode. When PVF+ClO4- and PANI were codeposited by cycling the potential between 0.20 and 1.80 V vs Ag vertical bar AgCl, these polymers were encapsulated within each other. The encapsulation of PVF+ClO4 inside the growing PANI polymer provided the retainment of PVF+ClO4 on the electrode surface even if it was in dedoped form (PVF). This composite film was characterized by cyclic voltammetry, FTIR, SEM and conductivity measurements. The response of the composite film to catechol and hydroquinone was investigated by chronocoulometry in aqueous medium. It was found that the increase in charge consumption for catechol and hydroquinone was observed up to 7.5 and 5.0 times, respectively, when compared to that of PANI film. This might be due to the presence of PVF+ClO4- in the composite film, which played an important role in accelerating the electron transfer.
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    Fabrication and characterization of poly(vinylferrocenium) perchlorate/poly(3,4-ethylenedioxythiophene) composite-coated electrode in methylene chloride
    (Elsevier Science Sa, 2012) Sen Teker, Mine; Tamer, Ugur; Pekmez, Nuran Ozcicek
    Poly(vinylferrocenium) perchlorate/poly(3,4-ethylenedioxythiophene) (PVF+/PEDOT) composite film was synthesized electrochemically on Pt electrode in a methylene chloride solution containing a mixture of poly(vinylferrocene) (PVF) polymer and 3,4-ethylenedioxythiophene monomer. PVF polymer in composite film was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. The resulting composite film was characterized electrochemically, spectroscopically and conductivity measurements. Ascorbic acid (AA) was selected as a model compound to evaluate the electrocatalytical ability of the PVF+/PEDOT composite film-coated electrode. The resulting coating exhibits significant electrochemical activity toward AA in 0.1 M phosphate buffer solution at pH 7, with high sensitivity and a wide linearity range. The steady state current vs. the concentration of AA are linear in the range of 2.22 x 10(-4)-6.4 x 10(-2) mol L-1 and 6.4 x 10(-2)-2.16 x 10(-1) mol L-1, respectively, for two linear regions. Limit of detection (LOD) was found to be 6.67 x 10(-5) mol L-1 at 0.35 V vs. SCE. The interaction of AA with PVF+ and PEDOT homopolymer films was investigated electrochemically and spectroscopically. The results showed that the catalytic activity of PEDOT-coated electrode was improved by the addition of PVF+. Applicability of the composite film was investigated by using pharmaceutical tablets, employing amperometric I-t method. (C) 2012 Elsevier B.V. All rights reserved.