Browsing by Author "Kiymaz A."

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    Enhanced performance of ultra-thin polyaniline supercapacitor via aniline blue-WS SAMs with rich nucleation site
    (IOP Publishing Ltd, 2021) Kiymaz D.; Kiymaz A.; Dincalp H.; Zafer C.
    We report the ultrathin supercapacitor's superior performance via the vertically aligned one-dimensional polyaniline structure (1D PANI) growth on the fluorine-doped tin oxide (FTO) substrate. FTO electrodes were treated by the molecular-self assembly, and the effects of different self assembled monolayers (SAMs) on both the evolution of PANI and electrochemical performance were examined. We obtained 809.09 F g−1 specific capacitance from ∼120 nm thick PANI (at 20 mV s−1 scan rate of cyclic voltammetry) via aniline blue water soluble SAMs modification. The supercapacitor's internal dynamics were clarified by a new equivalent circuit model developed from the Graham model. Through the new model, accurate information about double-layer capacitance, percolation capacitance, and bulk capacitance, which composes the electrode's capacitive performance, could be obtained. This work provided novel knowledge to develop PANI deposition and hence to achieve greater capacitances. © 2021 IOP Publishing Ltd Printed in the UK
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    Charge transport kinetics in flower like α-MnO2 nano-sheet and α-MnO2 nanowire based supercapacitors
    (Elsevier B.V., 2022) Kiymaz D.; Kiymaz A.; Tekoglu S.; Mayr F.; Dincalp H.; Zafer C.
    In a supercapacitor, determining the cells’ internal dynamics and limiting factors on the efficiency is essential for device designs. In this context, electrochemical impedance spectroscopy is a powerful tool in investigating device kinetics. This study explained the performance improvement in nanostructured MnO2 electrodes from a diffusion perspective. Firstly, we reported morphological features of flower-like nanosheet MnO2 and nanowire MnO2 with identical crystal structure (α-MnO2 phase) and capacitance-voltage properties. Then, the factors limiting the bias voltage-dependent capacitance efficiency were explained via electrochemical impedance spectroscopy by setting up a three-electrode system. Both resistance and capacitance vs. frequency plots provided important information on ion diffusion and charge transfer mechanisms. © 2022 Elsevier B.V.