Yazar "Karazehir, Tolga" seçeneğine göre listele

Listeleniyor 1 - 18 / 18
  • Küçük Resim
    Öğe
    A novel synthesis of (3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9-(4-vinylbenzyl)-9H-carbazole), alternating polymer formation, characterization, and capacitance measurements
    (Springer, 2013) Ateş, Murat; Uludağ, Nesimi; Karazehir, Tolga; Arican, Fatih
    In this work, (3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9-(4-vinylbenzyl)-9H-carbazole) (EDOTVBCz) comonomer was chemically synthesized and characterized by Fourier transform infrared (FTIR), proton nuclear magnetic resonance, and carbon nuclear magnetic resonance spectroscopy. EDOTVBCz was electrocoated on glassy carbon electrode (GCE) in various initial molar concentrations ([EDOTVBCz](0) = 1.0, 1.5, 2.0, and 3.0) in 0.1 M lithium perchlorate (LiClO4)/acetonitrile (CH3CN). P(EDOTVBCz)/GCE was characterized by cyclic voltammetry, FTIR reflectance-attenuated total reflection spectroscopy, scanning electron microscopy-energy dispersive X-ray analysis, atomic force microscopy, and electrochemical impedance spectroscopy (EIS). EIS was used to determine the capacitive behaviors of modified GCE via Nyquist, Bode magnitude, Bode phase, and admittance plots. The highest low-frequency capacitance value was obtained as C (LF) = similar to 2.35 mF cm(-2) for [EDOTVBCz](0) = 3.0 mM. Double-layer capacitance of the polymer/electrolyte system was calculated as C (dl) = similar to 2.78 mF cm(-2) for [EDOTVBCz](0) = 1.0 and 3.0 mM. The maximum phase angle was obtained as theta = similar to 76.7(o) for [EDOTVBCz](0) = 1.0, 1.5, 2.0, and 3.0 mM at the frequency of 20.6 Hz. AC impedance spectra of P(EDOTVBCz)/LiClO4/CH3CN was obtained by performing electrical equivalent circuit model of R(Q(R(CR))) with linear Kramers-Kronig test.
  • Küçük Resim
    Öğe
    A novel synthesis of 3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9-tosyl-9H-carbazole
    (Ovidius Univ Press, 2012) Ateş, Murat; Uludağ, Nesimi; Karazehir, Tolga; Arican, Fatih
    3,6-bis(2,3-dihydrothieno [3,4-b][1,4]dioxin-5-yl)-9-tosyl-9H-carbazole (EDOTTsCz) was synthesized and electrochemically polymerized on glassy carbon electrode (GCE) in 0.1 M tetrabutyl ammonium tetrafluoroborate (NB4BF4)/acetonitrile (CH3CN). Alternating copolymer was formed by CV method. Modified polymer electrode was characterized by Fourier transform Infrared Spectroscopy-Attenuated Transmission Reflectance (FTIR-ATR), Cyclic voltammetry (CV), Scanning electron microscopy-Energy dispersive X-ray analysis (SEM-EDX), Atomic force microscope (AFM) and Electrochemical impedance spectroscopy (EIS). Capacitive behaviors of the modified GCE were defined via Nyquist, Bode-magnitude, Bode-phase and Capacitance plots. A modified copolymer electrode provides enhanced capacitance evaluation, which may results in performance in energy storage devices.
  • Küçük Resim
    Öğe
    A novel synthesis of 4-toluene 9H-carbazole-9-carbodithioate, electropolymerization and impedance study
    (Budapest Univ Technol & Econ, 2014) Ateş, Murat; Uludağ, Nesimi; Karazehir, Tolga; Arican, Fatih
    A novel synthesis of 4-toluene 9H-carbazole-9-carbodithioate (TCzC) was chemically synthesized and characterized by Fourier Transform Infrared (FTIR), proton nuclear magnetic resonance (H-1-NMR), and carbon nuclear magnetic resonance (C-13-NMR) spectroscopies. Specific (C-sp) and double layer capacitances (C-dl) of the electro-coated poly(carbazole) and poly(TCzC) films were obtained on glassy carbon electrode (GCE) by impedimetric method with DC potential from -0.1 to + 1.0 V by increasing potential of 0.2 V. The polymers were characterized by Cyclic voltammetry (CV), Fourier transform infrared reflectance-attenuated total reflection spectroscopy (FTIR-ATR), Atomic force microscopy (AFM), and Electrochemical impedance spectroscopy (EIS). The use of additional variable (DC potential) helped to disambiguate the equivalent circuit model of R(C(R(Q(RW))))(CR). Simulation results were compared with experimental data. In this study, substituted group effects of CS2 and tosyl on carbazole polymer were investigated by EIS technique. CS2 group together with tosyl group in the structure of carbazole decreased the specific capacitance value (C-sp = 0.43 mF cm(-2)) compared to PCz (C-sp = 1.44 mF cm(-2)). Electropolymerization formation was seriously affected by substituted groups of CS2 and tosyl on conjugation system because of the electron donor and acceptor ability.
  • Küçük Resim
    Öğe
    Comparison of electrolyte effects for poly(3,4-ethylenedioxythiophene) and poly(3-octylthiophene) by electrochemical impedance spectroscopy and polymerization parameters with morphological analyses on coated films
    (Springer, 2013) Ateş, Murat; Karazehir, Tolga; Arican, Fatih; Eren, Nuri
    3,4-Ethylenedioxythiophene and 3-octylthiophene were electropolymerized on glassy carbon electrodes (GCE) to compare with four different electrolytes [lithium perchlorate (LiClO4), sodium perchlorate, tetraethylammonium tetrafluoroborate, and tetrabutylammonium tetrafluoroborate] in a solvent of acetonitrile (CH3CN). Modified electrodes were characterized by cyclic voltammetry, attenuated total reflectance-Fourier transform IR spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, atomic force microscopy, and electrochemical impedance spectroscopy (EIS). Nyquist and Bode plots for magnitude, phase, admittance, and capacitance on both polymer-modified electrodes were comparatively investigated in detail. The highest low-frequency capacitance (C (LF)) and double-layer capacitance (C (dl)) were obtained in 0.1 M LiClO4/CH3CN for poly(3,4-ethylenedioxythiophene) and poly(octylthiophene)/GCE. EIS data were fitted to the equivalent circuit model of R(Q(R(C(R(C(RW))))))(CR), which is used to investigate circuit parameters.
  • Küçük Resim
    Öğe
    Copolymer formation of 9-(2-(benzyloxy)ethyl)-9H-carbazole and 1-tosyl-1H-pyrrole coated on glassy carbon electrode and electrochemical impedance spectroscopy
    (Springer, 2012) Ateş, Murat; Uludağ, Nesimi; Karazehir, Tolga
    In this work, 9-(2-(benzyloxy)ethyl)-9H-carbazole (BzOCz) and 1-tosyl-1H-pyrrole (TsP) monomers were chemically synthesized and characterized by Fourier transform infrared reflectance (FTIR) and proton nuclear magnetic resonance (H-1-NMR) spectroscopy. BzOCz and TsP were electrocoated on glassy carbon electrode (GCE) in various molar fractions (X (TsP) = 0.5, 0.83, 0.91, and 0.98) in 0.1 M sodium perchlorate/acetonitrile. The detailed characterization of poly(BzOCz-co-TsP) was studied by cyclic voltammetry, FTIR-attenuated total reflection spectroscopy and electrochemical impedance spectroscopy (EIS). The effects of different molar fractions during the preparation of modified electrodes were studied by EIS technique. The AC impedance technique was used to determine the capacitive behaviors of modified GCE via Nyquist, Bode magnitude, and Bode phase plots. The highest low frequency capacitance value was obtained as C (LF) = 23.94 mu F cm(-2) for X (TsP) = 0.98. Therefore, synthesized copolymer has more capacitive behavior than its homopolymers, such as C (LF) = 7.5 mu F cm(-2) for poly(BzOCz) and C (LF) = 9.44 mu F cm(-2) for poly(TsP). In order to interpret the AC impedance spectra, R(Q(RW)) electrical equivalent circuit was employed with linear Kramers-Kronig test. A mechanism for electropolymerization has been proposed for copolymer formation.
  • Küçük Resim
    Öğe
    Covalent Immobilization of Urease on Poly(Pyrrole-3-carboxylic Acid): Electrochemical Impedance and Mott Schottky Study
    (Electrochemical Soc Inc, 2016) Karazehir, Tolga; Ateş, Murat; Saraç, A. Sezai
    Pyrrole-3-carboxylic acid was electropolymerized on a glassy carbon electrode in 0.1 M NaClO4/ACN, Et4NBF4/ACN using cyclic voltammetry. Urease (Urs) was immobilized onto PPCA modified GCE via covalent binding, exploiting EDC/NHS chemistry. Electrochemical impedance spectroscopy was used to investigate the interfacial behavior of Urs immobilized PPCA surfaces at open circuit potential. The impedance spectra were fitted before and after immobilization of Urs using equivalent circuits of R(C(R(Q(RW)))). After immobilization of Urs onto the PPCA matrix, the charge transfer resistance (R-CT) increased for electrodes, which R-CT of urease immobilized PPCA-NaClO4 matrixes were lower than that of the Urs immobilized PPCA-Et4NBF4 matrixes indicating higher charge transfer ability. A decrease in double layer capacitance (C-dl) values when Urs was immobilized at the PPCA-NaClO4 electrode surface was observed, whereas an increase at the PPCA-Et4NBF4 electrode surface was observed. Urs immobilized electrodes resulted in a n-type semiconducting behavior revealing a positive slope. An increase in acceptor concentration of the electrodes, and a shift of the E-FB to more positive values with increasing amount of urease was observed. The Urs based electrode (PPCA-NaClO4-Urs) was used for detection of urea, which was detected in range of 0.9 to 14 mM with a detection limit (LOD) of 8.28 mu M. (C) 2016 The Electrochemical Society. All rights reserved.
  • Küçük Resim
    Öğe
    Electrochemical copolymerization of N-methylpyrrole and 2,2 '-bithitiophene; characterization, micro-capacitor study, and equivalent circuit model evaluation
    (Indian Acad Sciences, 2013) Ateş, Murat; Arican, Fatih; Karazehir, Tolga
    N-methylpyrrole (N-MPy) and 2,2'-bithiophene (BTh) were electrocopolymerized in 0 center dot 2 M acetonitrile-sodium perchlorate solvent-electrolyte couple on a glassy carbon electrode (GCE) by cyclic voltammetry (CV). The resulting homopolymers and copolymers in different initial feed ratios of [N-MPy](0)/[BTh](0) = 1/1, 1/2, 1/5 and 1/10 were characterized by CV, Fourier-transform infrared reflectance attenuated transmittance (FTIR-ATR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and electrochemical impedance spectroscopy (EIS). The capacitive behaviours of the modified electrodes were defined via Nyquist, Bode-magnitude, Bode-phase and admittance plots. The equivalent circuit model of R(C(R)(QR)(CR)) was performed to fit theoretical and experimental data. The highest low-frequency capacitance (C (LF)) were obtained as C (LF) = similar to 1 center dot 23 x 10 (-4) mF cm (-2) for P(N-MPy), C (LF) = similar to 2 center dot 09 x 10 (-4) mF cm(-2) for P(BTh) and C (LF) = similar to 5 center dot 54 x 10 (-4) mF cm(-2) for copolymer in the inital feed ratio of [N-MPy](0)/[BTh] (0) = 1/2.
  • Küçük Resim
    Öğe
    Electrolyte effects of poly(3-methylthiophene) via PET/ITO and synthesis of 5-(3,6-di(thiophene-2-yl)-9H-carbazole-9-yl) pentanitrile on electrochemical impedance spectroscopy
    (Wiley-Blackwell, 2012) Ateş, Murat; Karazehir, Tolga; Uludağ, Nesimi
    In this article, 3-methylthiophene (3MTh) and 5-(3,6-di(thiophene-2-yl)-9H-carbazole-9-yl) pentanitrile (ThCzpN) comonomer were electrochemically deposited on poly(ethylene terephthalate)/indium tin oxide (PET/ITO) electrode and carbon fiber micro electrode (CFME) in sodium perchlorate (NaClO4)/acetonitrile (ACN), respectively. ThCzpN comonomer was characterized by 1H-nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy (FTIR) analysis. Poly(ThCzpN)/CFME is characterized by cyclic voltammetry (CV), Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), and electrochemical impedance spectroscopy (EIS). The detailed characterization of the resulting electrocoated poly(3MTh) on PET/ITO thin films was studied by different techniques, i.e., CV and EIS. The effects of electrolytes after electrocoated of modified electrodes were examined by EIS technique in various electrolytes medium (sodium perchlorate (NaClO4), lithium perchlorate (LiClO4), tetraethyl ammonium tetrafluoroborate (TEABF4), and tetrabutyl ammonium tetrafluoroborate (TBABF4)/acetonitrile (ACN) solution). Capacitive behaviors of modified PET/ITO electrode were defined via Nyquist, Bode-magnitude, Bode-Phase, and admittance plots. Variation of capacitance values by various electrolytes and low-frequency capacitance (CLF) values are presented. CLF value electrocoated polymer thin film by CV method in the 0.1M NaClO4 electrolyte with a charge of 7.898 mC was obtained about 59.1 mF cm-2. The highest low-frequency capacitance (CLF) was obtained from the Nyquist plot with [ThCzpN]0 = 3 mM as 0.070 mF cm-2. Equivalent circuit model [R(QR(CR)(RW))(CR)] was suggested for poly(3MTh) on PET/ITO in four different electrolytes medium. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
  • Küçük Resim
    Öğe
    Electrolyte type and concentration effects on poly(3-(2-aminoethyl thiophene) electro-coated on glassy carbon electrode via impedimetric study
    (Springer, 2013) Ateş, Murat; Karazehir, Tolga; Arican, Fatih; Eren, Nuri
    In this study, 3-(2-Aminoethyl thiophene) (2AET) monomer was electropolymerized on glassy carbon electrode (GCE) using various electrolytes (lithium perchlorate (LiClO4), sodium perchlorate (NaClO4), tetrabutyl ammonium tetra fluoroborate (TBABF(4)) and tetraethyl ammonium tetra fluoroborate (TEABF(4)) in acetonitrile (CH3CN) as solvent. Poly(3-(2-aminoethyl thiophene) (P(2AET))/GCE was characterized by cyclic voltammetry (CV), Fourier transform infrared reflectance spectrophotometry (FTIR-ATR), scanning electron microscopy, energy dispersive X-ray analysis (EDX), and electrochemical impedance spectroscopy (EIS) techniques. The electrochemical impedance spectroscopic results were given by Nyquist, Bode-magnitude, Bode-phase, capacitance and admittance plots. The highest low frequency capacitance (C-LF) value obtained was 0.65 mF cm(-2) in 0.1 M LiClO4/CH3CN for the initial monomer concentration of 1.5 mM. The highest double layer capacitance (C-dl = similar to 0.63 mF cm(-2)) was obtained in 0.1 M LiClO4/ACN for [2AET](0) = 0.5, 1.0 and 1.5 mM. The maximum phase angles (theta = 76.1 degrees at 26.57 Hz) and conductivity (Y '' = 3.5 mS) were obtained in TEABF(4)/ACN for [2AET](0) = 0.5 and 1.0 mM, respectively. An equivalent circuit model of R(Q(R(Q(R(CR))))) was simulated for different electrolytes (LiClO4, NaClO4, TBABF(4) and TEABF(4))/P(2AET)/GCE system. A good fitting was obtained for the calculated experimental and theoretical EIS measurement results. The electroactivity of P(2AET)/GCE opens the possibility of using modified coated electrodes for electrochemical micro-capacitor electrodes and biosensor applications.
  • Küçük Resim Yok
    Öğe
    Electropolymerization of 9-Carbazole Acetic Acid in Room Temperature Ionic Liquid-Acetonitrile Mixture: Morphology, Capacitance, and Mott-Schottky Analysis
    (Electrochemical Soc Inc, 2016) Karazehir, Tolga; Ateş, Murat; Saraç, A. Sezai
    In this study, the electrochemical polymerization of 9-carbazole acetic acid (CzA) monomer was synthesized in various feed ratios of room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) in acetonitrile (ACN) to investigate the effect of RTIL on morphology, impedance, capacitance, and semiconducting properties. It was observed that the low amounts of the RTIL (10 and 20%) in the mixture improve the electrochemical polymerization process compared to the RTIL-free electrolyte. Indeed, after a certain amount% BMIMBF4 which was threshold (40%), the process turned strongly unfavored. Scanning electron microscopy (SEM) was used to understand the influence of the feed ratio of BMIMBF4 to ACN on the surface structure of obtained polymer films. The surface morphology of PCzA revealed dependence on the feed ratio of BMIMBF4. Electrochemical impedance spectroscopic (EIS) experiments were performed in a pure BMIMBF4 (100%) indicated that as the feed ratio of BMIMBF4 increased, the capacitive behavior of the polymer decreased. From the Mott-Schottky analysis, the highest flatband potential (E-FB = 2.87 V) was obtained for the 40% PCzA-BMIMBF4 film. (C) 2016 The Electrochemical Society. All rights reserved.
  • Küçük Resim
    Öğe
    Electrospun carbon nanofiber web electrode: Supercapacitor behavior in various electrolytes
    (Wiley, 2018) Ismar, Ezgi; Karazehir, Tolga; Ateş, Murat; Saraç, A. Sezai
    Carbon nanofibers (CNFs) draw great interest due to their noticeable mechanical, electrochemical, and physical properties. In this study, polyacrylonitrile-based CNFs are obtained via electrospinning technique. Thermal oxidation and low temperature (950 degrees C) carbonization are applied to the electrospun web in order to achieve CNF. Through the process, Fourier transform infrared-attenuated total reflectance spectroscopy and Raman spectroscopic results are investigated. The electrochemical properties of the self-standing CNF webs are examined with electrochemical impedance spectroscopy and cyclic voltammetry. In addition, various electrolyte solutions are studied to investigate the capacitive behavior of CNF webs. Electrolyte type variation has a significant effect on the capacitance results and high capacitance values are achieved in aqueous solution. According to the differing electrolyte types, specific capacitance values (C-sp) are recorded between 204 and 149 Fg(-1) where maximum specific capacitance is obtained in 0.5 M H2SO4 as 204 Fg(-1). (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45723.
  • Küçük Resim
    Öğe
    Glucose oxidase immobilization onto Au/poly[anthranilic acid-co-3-carboxy-N-(2-thenylidene)aniline]/PVAc electrospun nanofibers
    (Springer, 2017) Golshaei, Rana; Karazehir, Tolga; Ghoreishi, Sayed Mehdi; Ateş, Murat; Saraç, A. Sezai
    Au/poly[anthranilic acid-co-3-carboxy-N-(2-thenylidene)aniline/PVAc] [Au/P(ANA-co-CNTA)/PVAc] electrospun nanofibers were fabricated in different electrospinning media including acetone and dimethylformamide (DMF) for covalent immobilization of glucose oxidase (GOx). The surface of copolymer nanofibers was activated by EDC/NHS chemistry, and the presence of Au nanoparticles as tiny conduction centers inside the copolymer matrix enhanced the electrochemical properties. Morphology and composition of enzyme-immobilized nanofibers were characterized by scanning electron microscopy/energy-dispersive X-ray spectroscopy (EM/EDX) and atomic force microscope (AFM). The effective covalent binding of glucose oxidase onto the Au/P(ANA-co-CNTA)/PVAc nanofibers was also confirmed by FTIR-ATR and Raman spectroscopy. EIS measurements revealed that the charge transfer resistances of the enzyme-immobilized nanofibers were decreased with increasing amount of enzyme. The effect of electrospun nanofiber diameter on sensing properties of enzyme-functionalized nanofibers was investigated by EIS. The sensitivities of electrodes calculated from impedance measurement were 7.24 x 10(6) and 6.67 x 10(3) Omega mM(-1) cm(-2) for the Au/P(ANA-co-CNTA)/PVAc-GO(X) (DMF) and Au/P(ANA-co-CNTA)/PVAc-GO(X) (acetone), respectively. The impedance measurement results revealed that the linear range of Au/P(ANA-co-CNTA)/PVAc-GO(X) (DMF) was lower than Au/P(ANA-co-CNTA)/PVAc-GO(X) (acetone). It could be attributed that smaller fiber diameter resulted in the higher specific surface area. This contributes to increasing the number of available active sites and, thus, increasing the amount of the enzyme loading.
  • Küçük Resim
    Öğe
    Gold nanoparticle/nickel oxide/poly(pyrrole-N-propionic acid) hybrid multilayer film: Electrochemical study and its application in biosensing
    (Budapest Univ Technol & Econ, 2017) Karazehir, Tolga; Gökçe, Z. Güler; Ateş, Murat; Saraç, A. Sezai
    The present study describes the fabrication of Indium Tin Oxide /gold nanoparticles/nickel oxide/poly(PyrroleN-propionic acid) (ITO/GNPs/NiO/poly(PPA)) multilayered film, and its modification with Tyrosinase (Ty). The ITO/GNPs/ NiO/poly(PPA) electrode was fabricated by sequential electrochemical assembly onto ITO substrate which electrochemical deposition provides a facile, inexpensive technique for synthesis of multilayered film within the adherent morphology with controllable film thickness. Cyclic voltammetry (CV), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), scanning electron microcopy (SEM), and atomic force microcopy (AFM) were used to characterize the film assembly processes. The properties of a semiconductor/electrolyte interface were investigated based on the Mott-Schottky (M-S) approach for the modified electrodes, with the flat band potential (E-FB) according to the potential intercept and the carrier density (N-D) according to the linear slopes. The N-D and EFB of ITO/GNPs/NiO/poly(PPA) were obtained as 2.48 . 1021 cm(-3) and 0.26 V, respectively. Tyrosinase was immobilized using carbodiimide coupling reaction. The bioelectrode was characterized by FTIR-ATR, SEM, AFM, electrochemical impedance spectroscopy (EIS). A Randles equivalent circuit was introduced for modeling the performance of impedimetric biosensing for the detection of the dopamine (DP) and the interface of bioelectrode/electrolyte. The EIS of the ITO/GNPs/NiO/poly(PPA)-Ty exhibited significant changes in the charge transfer resistance (R-CT) value toward the detection of dopamine over a linear range of 80 mu M to 0.2 mM with a limit of detection (LOD) of 5.46 mu M.
  • Küçük Resim
    Öğe
    Micro-Capacitor Behavior of Poly(3-Hexyl Thiophene)/Carbon Fiber/Electrolyte System and Equivalent Circuit Model
    (Taylor & Francis Inc, 2012) Ateş, Murat; Karazehir, Tolga
    In this article, 3-Hexyl thiophene (3HTh) monomer was electrocoated on carbon fiber micro electrode (CFME) to study electrochemical impedance spectroscopic (EIS) analysis. Poly(3HTh)/CFME is characterized by Cyclic voltammetry (CV), Fourier transform infrared reflectance-attenuated total reflection spectroscopy (FTIR-ATR), Scanning electron microscopy-Energy Dispersive X-ray analysis (SEM-EDX), and electrochemical impedance spectroscopy (EIS). The effects of different monomer concentrations (0.5, 1.0 and 1.5mM) on polymer were reported in 0.1M tetraethyl ammonium tetrafluoroborate (TEABF4)/acetonitrile (ACN) solution. The highest low frequency capacitance (C-LF = 1.394 mF cm(-2)) was obtained for [3HTh](0) = 0.5mM. The equivalent circuit model of R(QR(CR)(RW))(CR) was examined for polymer/electrolyte system.
  • Küçük Resim
    Öğe
    Mott-Schottky and Morphologic Analysis of Poly(Pyrrole-N-Propionic Acid) in various electrolyte systems
    (Esg, 2015) Karazehir, Tolga; Ateş, Murat; Saraç, A. Sezai
    In this study, pyrrole-N-propionic acid (PPA) was electrochemically polymerized on a glassy carbon electrode (GCE) in various electrolytes (NaClO4, Et4NBF4, Bu4NClO4, and Bu4NPF6) using cyclic voltammetry (CV). The structure and morphology of the modified electrode was characterized by FTIR-ATR, visible-near-infrared spectroscopy (Vis-NIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The morphological characterizations of the poly(PPA) films synthesized in the various supporting electrolyte solutions were demonstrated by SEM and AFM. Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis were performed to collect information about the semiconducting properties of the poly(PPA) films. From the Mott-Schottky analysis, the carrier densities (N-D) of the poly(PPA) films obtained were 3.25x10(16),1.59x10(16), 1.17x10(16), and 0.52x10(16) cm(-3), and the flat-band potentials were 0.41, 0.32, 0.37, and 0.36 V for the poly(PPA)films in NaClO4, Et4NBF4, Bu4NClO4, Bu4NPF6, respectively. The resulting Mott-Schottky plots of the poly(PPA) films indicate that the films are p-type semiconductors. EIS analysis were performed to determine the capacitive behaviors by variation of electrolyte types in a monomer-free solution. An equivalent-circuit model of R(W(CR)(QR))(CR) was used to fit the theoretical and experimental data to interpret the polymer electrode/electrolyte interface properties and to provide information about equivalent circuit parameters.
  • Küçük Resim
    Öğe
    Supercapacitor Behavior of Poly(Carbazole-EDOT) Derivatives/Multi-Walled Carbon Nanotubes, Characterizations and Equivalent Circuit Model Evaluations
    (Taylor & Francis Inc, 2014) Ateş, Murat; Uludağ, Nesimi; Karazehir, Tolga; Arican, Fatih
    Three new different comonomers of carbazole-EDOT derivatives had been previously synthesized and characterized in detail. In this study, electroactive materials were electropolymerized onto multi-walled carbon nanotube (MWCNT) modified glassy carbon (GC) electrode in 0.1M sodium dodecyl sulphate (SDS) solution. The electrochemical impedance spectroscopic results of Nyquist, and Bode-magnitude and Bode-phase plots show that polymers/MWCNT composites possess good capacitive characteristics. P(Com2)/MWCNT/GCE system's specific capacitance was up to Sc=132.6Fg(-1) at the scan rate of 70mVs(-1) from the area formula, Eq. (1). Furthermore, P(Com2)/MWCNT composite had very rapid charge/discharge ability with specific capacitance of Sc=75.23Fg(-1) at DC potential of 0.3V from Nyquist plot, and Sc=90.53Fg(-1) at the scan rate of 60mVs(-1) from charge formula, Eq. (2), which is important practical advantage. In addition, such composite had a good cycling performance and a wide potential window. Long-term stability of the capacitor was also tested by CV, and the results indicated that, after 500cycles, the specific capacitance was still at approximate to 100.0%, approximate to 89%, and approximate to 97.0% of the initial capacitance for P(Com1)/MWCNT, P(Com2)/MWCNT, and P(Com3)/MWCNT, respectively. An equivalent circuit model of R-s(C-1(R-1(Q(R2W))))(CGCRGC) was obtained to fit the experimental and theoretical data. Solution resistance (Rs) and resistance from GCE decrease gradually. However, capacitance of film (C-1), constant phase element (Q), and n values increase for P(Com1), P(Com2), and P(Com3)/MWCNT, respectively. Therefore, more homogeneous and less rough surface composite film was obtained by addition of MWCNT in the composite material.
  • Küçük Resim
    Öğe
    Synthesis of 2-(3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-carbazole-9-yl)ethyl Methacrylate, Electropolymerization, Characterization and Impedimetric Study
    (Electrochemical Soc Inc, 2013) Ateş, Murat; Uludağ, Nesimi; Karazehir, Tolga; Arican, Fatih
    In this work, 2-(3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-carbazole-9-yl)ethyl methacrylate (EDOTCzMetac) was chemically synthesized and characterized by FTIR, H-1-NMR, and C-13-NMR. A novel synthesized comonomer was firstly electropolymerized on glassy carbon electrode (GCE) in various initial molar concentrations [EDOTCzMetac] 0 = 1.0, 3.0, 5.0 and 10.0 mM) in 0.1 M tetraethyl ammonium tetrafluoroborate (TEABF(4))/acetonitrile (CH3CN). Poly(EDOTCzMetac)/GCE was characterized by the technique of Cyclic Voltammetry (CV), Fourier Transform Infrared Reflectance-Attenuated Total Reflection Spectroscopy (FTIR-ATR), Scanning Electron Microscopy-Energy Dispersive X-ray analysis (SEM-EDX), Atomic Force Microscope (AFM) and Electrochemical impedance spectroscopy (EIS). The capacitive behavior of modified electrode was obtained via EIS method by the help of Nyquist, Bode-magnitude, Bode-phase, and Admittance plots. The highest low frequency capacitance (C-LF) value was obtained as 4.99 mF cm(-2) for [EDOTCzMetac](0) = 10.0 mM. Therefore, the synthesized copolymer for [EDOTCzMetac](0) = 10 mM has more capacitive behavior than the initial monomer concentration for [EDOTCzMetac](0) = 1.0 mM as C-LF = 3.63 mF cm(-2), for [EDOTCzMetac](0) = 3.0 mM as C-LF = 4.10 mF cm(-2) and for [EDOTCzMetac](0) = 5.0 mM as C-LF = 4.67 mF cm(-2). To interpret the AC impedance spectra, R(C(R(Q(RW))))(CR) electrical equivalent circuit was employed with linear Kramers-Kronig test. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.011302jes] All rights reserved.
  • Küçük Resim
    Öğe
    Synthesis of methyl 4-(9H-carbazole-9-carbanothioylthio) benzoate: electropolymerization and impedimetric study
    (Scientific Technical Research Council Turkey-Tubitak, 2015) Ateş, Murat; Uludağ, Nesimi; Arican, Fatih; Karazehir, Tolga
    Methyl 4((9H-(carbazole-97carbanothioylthio) benzoate (MCzCTB) was chemically synthesized and characterized by FTIR, H-1 NMR, and C-13 NMR. A novel synthesized monomer was electropolymerized on a glassy carbon electrode (GCE) in various initial molar concentrations of [MCzCTB](0) = 1, 3, 5, and 10 mM in 0.1 M NaClO4/CH3CN and 1 M H2SO4 center dot P(MCzCTB)/GCE was characterized by cyclic voltammetry, Fourier transform infrared-attenuated transmittance reflectance, scanning electron microscopy-energy dispersive X-ray, and electrochemical impedance spectroscopy. The capacitive behavior of the modified electrode was obtained by Nyquist, Bode-magnitude, and Bode-phase plots. The highest capacitance at low frequency was obtained as similar to 53.1 mF cm(-2) from Nyquist plot and 19.454 Fg(-1) at a scan rate of 10 mV s(-1) for [MCzCTB](0) = 1.0 mM. CS2 and OCH3 groups are electron-withdrawing and electron-donating groups in the monomer structure. These groups affect the polymerization and capacitive behavior of the polymer. The polymer may be used for supercapacitor and biosensor applications in the future.