Browsing by Subject "Glassy carbon electrodes"

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    Electrochemical deposition and behavior of mixed-valent molybdenum oxide film at glassy carbon and ITO electrodes
    (Elsevier B.V., 2013) Koçak S.; Ertaş F.N.; Dursun Z.
    The effect of solution composition and the type of the anionic species on the electrochemical formation of mixed-valent molybdenum oxide on a glassy carbon and ITO electrode surfaces was elucidated. Susccessive recording of the voltammograms has shown that anionic species display different stabilizing effect on the reductive formation of hydrogen molybdenum bronzes [MoO 3-x (OH) x ] and chloroacetic acid buffer has given the best results. The deposit was built upon cycling the potential between 0 and -0.9 V (vs. Ag/AgCl) via reduction of Mo(VI) to Mo(V) on the electrode surface in pH 3.0 chloroacetic acid solution. Electrochemical impedance measurements carried out in this medium revealed a shift in potential zero charge values from -0.2 V to -0.55 V after the potential of the GCE had been cycled for 30 min. An establishment of mixed-valent molybdenum oxide deposit by time on the gold electrode surface was proved by quartz crystal microbalance measurements. Atomic force and scanning electron microscopy techniques were made use of so as to characterize the surface structures of the electrodes. X-ray photoelectron spectroscopy studies confirmed that the deposit contains both Mo(V) and Mo(VI). The deposited films exhibited unique catalytic activity towards nitrite oxidation consistent with the change in peak characteristics. © 2012 Elsevier B.V. All rights reserved.
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    Enhanced Electrochemical Determination of Catechol and Hydroquinone Based on Pd Nanoparticles/Poly(Taurine) Modified Glassy Carbon Electrode
    (Wiley-VCH Verlag, 2020) Koçak Ç.C.; Koçak S.
    Here, Pd nanoparticles and poly(taurine) film was prepared on the glassy carbon electrode surface (Pd/Poly(TAU)/GCE) by the rapid electrochemical technique. The proposed composite surface was characterized by scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS) and electrochemical impedance spectroscopy(EIS). Enhanced electron transfer ability and higher electroactive surface area were achieved at Pd/Poly(TAU)/GCE as compared to the bare GCE and polymer film electrode. The new and highly stable Pd/Poly(TAU)/GCE was employed for the individual and simultaneous determination of hydroquinone and catechol which were environmentally toxic. Under the optimized conditions, HQ and CC were individually determined by using the differantial pulse voltammetry in the linear ranges of 0.008–100 μM and 0.001–100 μM with the detection limits of (LOD) 2.1 nM and 0.68 nM, respectively. In case of simultaneous determination, LODs were found as 10 nM and 0.88 nM for HQ and CC, respectively. The content of both analytes in the real sample analysis was evaluated in the river water and tap water successfully. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Pulsed Deposited Manganese and Vanadium Oxide Film Modified with Carbon Nanotube and Gold Nanoparticle: Chitosan and Ionic Liquid-based Biosensor
    (Wiley-VCH Verlag, 2020) Akoğulları S.; Çιnar S.; Özdokur K.V.; Aydemir T.; Ertaş F.N.; Koçak S.
    Present study describes the synthesis of mixed oxide films of manganese and vanadium by electrochemical pulsed deposition technique on a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNT). The film was further decorated with gold nanoparticles to enhance the reduction signal of dissolved oxygen in pH 5.17 acetate buffer solution. All of the electrochemical synthesized modified electrodes have been characterized with Scanning electron microscopy(SEM), High-resolution transmission electron microscopy (HRTEM), X-Ray photoelectron spectroscopy (XPS), X-Ray diffraction (XRD) techniques. The electrode obtained (AuNPs/MnOx−VOx/CNT/GCE) was utilized as a platform for glucose biosensor where the glucose oxidase enzyme was immobilized on the composite film with the aid of chitosan and an ionic liquid. The electrochemical performance of the biosensor was investigated by cyclic voltammetry and the relative parameters have been optimized by amperometric measurements in pH 5.17 acetate buffer solution. The developed biosensor exhibited a linear range for glucose between 0.1–1.0 mM and the limit of detection was calculated as 0.02 mM. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim