• Journal of the Korean Electrochemical Society
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• v.13 no.1
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• pp.57-62
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• 2010

New monomers, possessing various alkyl substituents on propylene dioxypyrrole, were synthesized. The monomers could be easily polymerized to produce highly conductive and soluble polymers. The corresponding polymers showed excellent solubility, retaining electrochemical and optical properties of their parent polymer [poly(propylene dioxypyrrole)]. The conductivities of chemically prepared polymers were quite high in a range of 20 and $60\;Scm^{-1}$. Solubility of the polymer in a common organic solvent was as high as no polymer is deposited on an electrode. The redox potentials of the electrochemically prepared polymers revealed quite stable electro-activity during repeated redox switching up to 500 times. The optoelectrochemistry studies also showed distinct color changes of the polymers upon changing the doping state, indicating strong absorption peaks at 400~600 nm in reduced states and complete bleaching in fully oxidized states.

• Journal of Electrochemical Science and Technology
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• v.6 no.4
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• pp.111-115
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• 2015

In this work electrochemical oxidation of Ascorbic acid (AA) on the surface of Cobalt nano particle modified carbon paste electrode (CoNPsMCPE) was studied in alkaline media. CoNPs were green synthesized using Piper longum and a mixture of 5% (w/w) of it were made with carbon paste. CoNPs showed good electrocatalytic activity in alkaline media. Cyclic voltammetry (CV) and chronoamperometry (CA) were used to study the electrochemical performance of CoNPsMCPE. The number of monolayers on the surface of electrode was calculated as 1.08×10⁹ mol cm⁻² that is equal to that of metal Cobalt electrode. Diffusion coefficient of AA was determined using CA analysis which was equal to 1.5×10⁻⁶cm² s⁻¹.

• Journal of the Korean Electrochemical Society
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• v.9 no.3
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• pp.113-117
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• 2006

The electrochemical properties of the redox mediator, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) ($ABTS^{2-}$) were studied using cyclic voltammetry. The measured potentials (${E^o}'$ vs SCE) of the two redox couples of ABTS are 0.45 V for $ABTS^{2-}/ABTS^{\cdot-}$ and 0.87 V for $ABTS^{\cdot-}/ABTS^0$. The rate constant for heterogeneous electron transfer and the diffusion coefficients for $ABTS^{2-}$ are $5x10^{-3}cm\;s^{-1}$ and $3.1x10^{-6}cm^2\;s^{-1}$, respectively. Our interest in $ABTS^{2-}$ stems from the fact that this molecule functions as a substrate to the copper oxidase, laccase, by providing the reducing equivalents necessary for the biocatalyzed reduction of dioxygen to water. Consequently, when laccase is tethered to an electrode surface or dissolved in solution, $ABTS^{2-}$ can be used to quantify enzyme activity electrochemically.

• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.195-201
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• 2018

To enhance the performance of cathodes at low temperatures, a Cu-coated cathode is prepared, and its electrochemical performance is examined by testing its use in a single cell. At $620^{\circ}C$ and a current density of $150mAcm^{-2}$, a single cell containing the Cu-coated cathode has a significantly higher voltage (0.87 V) during the initial operation than does that with an uncoated cathode (0.79 V). According to EIS analysis, the high voltage of the cell with the Cu-coated cathode is due to the dramatic decrease in the high-frequency resistance related to electrochemical reactions. From XPS analysis, it is confirmed that the Cu is initially in the form of $Cu_2O$ and is converted into CuO after 150 h of operation, without any change in the state of the Ni or Li. Therefore, the high initial cell voltage is confirmed to be due to $Cu_2O$. Because $Cu_2O$ is catalytically active toward $O_2$ adsorption and dissociation, $Cu_2O$ on a NiO cathode enhances cell performance and reduces cathode polarization. However, the cell with the Cu-coated cathode does not maintain its high voltage because $Cu_2O$ is oxidized to CuO, which demonstrates similar catalytic activity toward $O_2$ as NiO.

• Journal of the Korean Electrochemical Society
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• v.23 no.3
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• pp.73-80
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• 2020

Fenton oxidation method using hydrogen peroxide is an eco-friendly oxidation method used in water treatment and soil restoration. When removing pollutants by this method, it is quite important to properly regulate the concentration of hydrogen peroxide according to the concentration of the contaminants. In this study, electrochemical biosensors using HRP (horseradish peroxidase) enzymes were manufactured and studies were conducted on the activity of enzymes and the detection characteristics of hydrogen peroxide. HRP were electro deposited with chitosan and AuNP on the working electrode surface of the SPCE (Screen Printed Carbon Electrode). Then, the fixation of enzymes was confirmed using the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The activity of HRP enzymes was also identified from chronoamperometry (CA) and UV spectroscopy. After immersing the biosensor in PBS solution the current generated from electrodes by titrating hydrogen peroxide was measured from CA analysis. The generated current increased linearly for the concentration of hydrogen peroxide, and a calibration curve was derived that could predict the concentration of hydrogen peroxide from the current.

• 한국전기화학회:학술대회논문집
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• 2002.10a
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• pp.12-12
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• 2002

• 대한핵의학회:학술대회논문집
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• 2005.11a
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• pp.335.1-335.1
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• 2005

• 한국전기화학회:학술대회논문집
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• 1999.04a
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• pp.31-31
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• 1999

• Journal of Electrochemical Science and Technology
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• v.12 no.1
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• pp.137-145
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• 2021

Among the non-precious metal catalysts, iron-nitrogen doped carbon (Fe-N/C) catalysts have been recognized as the most promising candidates for an alternative to Pt-based catalysts for the oxygen reduction reaction (ORR) under alkaline and acidic conditions. In this study, the nano replication method using mesoporous silica, which features tunable primary particle sizes and shape, is employed to prepare the mesoporous Fe-N/C catalysts with different shapes. Platelet SBA-15, irregular KIT-6, and spherical silica particle (SSP) were selected as a template to generate three different kinds of shapes of the mesoporous Fe-N/C catalyst. Physicochemical properties of mesoporous Fe-N/C catalysts are characterized by using small-angle X-ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy images. According to the electrochemical evaluation, there is no morphological preference of mesoporous Fe-N/C catalysts toward the ORR activity with half-cell configuration under alkaline electrolyte. By implementing X-ray photoelectron spectroscopy analysis of Fe and N atoms in the mesoporous Fe-N/C catalysts, it is possible to verify that the activity towards ORR highly depends on the portions of "Fe-N" species in the catalysts regardless of the shape of catalysts. It was suggested that active site distribution in the Fe-N/C is one important factor towards ORR activity.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.95.2-95.2
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• 2011

In order to achieve high performance and low cost for commercial applications, the development of membrane electrode assemblies (MEA), in which the electrochemical reactions actually occur, must be optimized. Expensive platinum is currently used as an electrochemical catalyst due to its high activity. Although various platinum alloys and non-platinum catalysts are under development, their stabilities and catalytic activities, especially in terms of the oxygen reduction (ORR), render them currently unsuitable for practical use. Therefore, it is important to decrease platinum loading by optimizing the catalysts and electrode microstructure. In this study, we prepared several different MEAs (non-uniform Nafion$^{(R)}$ ionomer loading electrode) which have dual catalyst layers to find the optimal Nafion$^{(R)}$ ionomer distribution in the electrodes. We changed Nafion$^{(R)}$ ionomer content in the layers to find the ideal composition of the binder and Pt/C in the electrode. For MEAs with various ionomer contents in the anodes and cathodes, the electrochemical activity (activation overpotential) and the mass transport properties (concentration overpotential) were analyzed and correlated with the single cell performance. The dual catalyst layers MEA showed higher cell performance than uniformly fabricated MEA, especially at the high current density region.