• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.697-706
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• 2005

We review the evolution of electrochemical studies of conducting polymers into the current state-of-the-art based primarily on our work. While conventional electrochemical experiments sufficed for the needs in the phase of studies of both electrochemical synthesis and characterization of conducting polymers, developments of various new experimental techniques have led to their introduction to this field for more refined information. As a result, the conventional electrochemical, spectroelectrochemical, electrochemical quartz crystal microbalance, impedance, and morphological as well as electrical characterization studies all made important contributions to a better understanding of the polymerization mechanisms and the conductive properties of these classes of polymers. From this review, we hereby expect that the electrochemical techniques will continue to play important roles in bringing this field to the practical applications such as nanoscale electronic devices.

• Journal of Electrochemical Science and Technology
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• 제6권1호
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• pp.16-25
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• 2015

Transition metal oxide nanocrystalline materials are playing major role in energy storage application in this scenario. Nickel oxide is one of the best antiferromagnetic materials which is used as electrodes in energy storage devices such as, fuel cells, batteries, electrochemical capacitors, etc. In this research work, nickel oxide nanoparticles were synthesized by combustion route in presence of organic fuels such as, glycine, glucose and and urea. The prepared nickel oxide nanoparticles were calcined at 600℃ for 3 h to get phase pure materials. The calcined nanoparticles were preliminarily characterized by XRD, particle size analysis, SEM and EDAX. To prepare nickel oxide electrode materials for application in supercapacitors, the calcined NiO nanoparticles were mixed with di-methyl-acetamide and few drops of nafion solution for 12 to 16 h. The above slurry was coated in the graphite sheet and dried at 50℃ for 2 to 4 h in a hot air oven to remove organic solvent. The dried sample was subjected to electrochemical studies, such as cyclic voltammetry, AC impedance analysis and chrono-coulometry studies in KOH electrolyte medium. From the above studies, it was found that nickel oxide nanoparticles prepared by combustion synthesis using glucose as a fuel exhibited resulted in low particle diameter (42.23 nm). All the nickel oxide electrodes have shown better good capacitance values suitable for electrochemical capacitor applications.

• Journal of Electrochemical Science and Technology
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• 제9권4호
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• pp.251-259
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• 2018

In general, the charge storage characteristics and overall performance of electrochemical energy devices (such as lithiumion batteries and supercapacitors) significantly depends on the structural and geometrical factors of the electrodes' active materials. The most widely used active materials of electrochemical energy storage devices are based on carbons of various forms. Each carbon type has drawbacks and advantages when used as the electrode material. Studies have been recently carried out to combine different types of carbons, in particular nanostructured carbons, in order to overcome the structure-originated limitations and thus enhance the overall electrochemical performances. In this feature article, we report the recent progress on the development of this novel class of materials (multidimensional nanocarbons), and their applications for supercapacitors. Multidimensional nanocarbons include graphenes/carbon nanotubes (CNTs), CNTs/carbon films, CNTs/fullerenes, and ternary carbon nanostructures. Various applications using these multidimensional nanocarbons have been proposed and demonstrated in the literature. Owing to the recent extensive studies on electrochemical energy storage devices and considering that carbons are their most fundamental electrode materials, the number of reports on nanocarbons employed as electrodes of the electrochemical energy storage devices is rapidly increasing. Recently, numerous multidimensional nanocarbons have been designed, prepared, and utilized as electrodes of electrochemical capacitors or supercapacitors, which are considered next-generation energy devices owing to their unique merits compared to the conventional structures. In this review, we summarize the basic motivations, preparation methods, and resultant supercapacitor performances of each class of multidimensional nanocarbons published in the literature, focusing on recent reports.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.98.2-98.2
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• 2013

Electrochemical phenomena underpin a broad spectrum of energy, chemical, and information technologies such as resistive memories and secondary batteries. The optimization of functionalities in these devices requires understanding electrochemical mechanisms on the nanoscale. Even though the nanoscale electrochemical phenomena have been studied by electron microscopies, these methods are limited for analyzing dynamic electrochemical behavior and there is still lack of information on the nanoscale electrochemical mechanisms. The alternative way can be an atomic force microscopy (AFM) because AFM allows nanoscale measurements and, furthermore, electrochemical reaction can be controlled by an application of electric field through AFM tip. Here, I will summarize recent studies to probe nanoscale electrochemical reaction in battery applications by AFM. In particular, we have recently developed electromechanical based AFM techniques for exploring reversible and irreversible electrochemical phenomena on the nanoscale. The present work suggests new strategies to explore fundamental electrochemical mechanisms using the AFM approach and eventually will provide a powerful paradigm for probing spatially resolved electrochemical information for energy applications.

• Journal of Electrochemical Science and Technology
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• 제4권2호
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• pp.61-70
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• 2013

Corrosion inhibition of carbon steel in 2M HCl by some benzohydrazide derivatives (I-III) was studied using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques at $30^{\circ}C$. Polarization studies showed that all the investigated compounds are of mixed type inhibitors. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the hydrazide derivatives, probably implying that physical adsorption of cationic species may be responsible for the observed inhibition behavior. Electrochemical impedance studies showed that the presence of benzohydrazide derivatives decreases the double layer capacitance and increases the charge transfer resistance. The adsorption of these compounds on carbon steel surface was found to obey Temkin's adsorption isotherm. Synergistic effects increased the inhibition efficiency in the presence of halide additives namely KI and KBr. An inhibition mechanism was proposed in terms of strongly adsorption of inhibitor molecules on carbon steel surface.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.231-243
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• 2019

The methanolic extracts of the leaves and stem of the plant Lepidagathis keralensis were evaluated for anticorrosion behavior against mild steel in 1M HCl. Corrosion inhibition studies were done by gravimetric method, electrochemical impedance spectroscopy and potentiodynamic polarization methods. Surface morphology of mild steel in the presence and absence of inhibitors were studied using SEM analysis. UV-Vis studies were also done to evaluate the mechanism of inhibition. Both the extracts showed good inhibition efficiency which increased with increase in concentration of the inhibitor and decreased with increase in temperature. The mechanism of inhibition was explained by adsorption which obeyed Langmuir adsorption isotherm. Thermodynamic calculations revealed a combination of both physisorption and chemisorption of the inhibitor on the surface of mild steel. The extracts behaved as mixed type inhibitors as determined by polarization studies. Quantum chemical studies on Phenoxyethene, one of the major components in the leaf extract of the plant was also carried out to support the experimental results.

• Korean Chemical Engineering Research
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• 제58권4호
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• pp.499-513
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• 2020

Among the many studies of carbon-based nanomaterials, carbon-based dots (CDs) have attracted considerable interest owing to their large surface area, intrinsic low-toxicity, excellent biocompatibility, high solubility, and low-cost with environmentally friendly routes, as well as their ability for modification with other nanomaterials. CDs have several applications in biosensing, photocatalysis, bioimaging, and nanomedicine. In addition, the fascinating electrochemical properties of CDs, including high active surface area, excellent electrical conductivity, electrocatalytic activity, high porosity, and adsorption capability, make them potential candidates for electrochemical sensing materials. This paper reviews the recent developments and synthesis of CDs and their composites for the proposed electrochemical sensing platforms. The electrochemical principles and future perspective and challenges of electrochemical biosensors are also discussed based on CDs-nanocomposites.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 춘계총회 및 학술발표회
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• pp.23-23
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• 2003

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.927-931
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• 2021

In this work, an attempt is made to improve the electrochemical corrosion resistance of Zircaloy-4 by helium ions implantation. For this purpose, the Zircaloy-4 was implanted with 300 keV helium ions of fluences 1 × 10¹³, 1 × 10¹⁵, and 1 × 10¹⁶ ions-cm^-2 by using Pelletron Accelerator. Electrochemical tests of pristine and ion-implanted samples were performed in NaCl solution and their potentiodynamic polarization curves were obtained. The results showed enhancement of the corrosion resistance of Zircaloy-4 after helium ions implantation. The corrosion rate and current density of the material were significantly reduced by the helium implantation. The decrease in corrosion parameters was attributed to helium ions diffusion inside Zircaloy-4 that reduced the electrons flow from the samples.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.153-160
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• 2016

The inhibition ability of N,N-bis(2,4-dihydroxyhydroxybenzaldehyde)-1,3-Propandiimine (DHBP) as a schiff base against the corrosion of API-5L-X65 steel in 1 M HCl solution was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy. Electrochemical impedance studies indicated that DHBP inhibited corrosion by blocking the active corrosion sites. The inhibition efficiency increased with increasing inhibitor concentrations. EIS data was analysed to equivalent circuit model and showed that the charge transfer resistance of steel increased with increasing inhibitor concentration whilst the double layer capacitance decreased. The adsorption of this compound obeyed the Langmuir adsorption isotherm. Gibbs free energy of adsorption was calculated and indicated that adsorption occurred through physical and spontaneous process. The corrosion inhibition mechanism was studied by potential of zero charge. Polarization studies indicated that DHBP retards both the cathodic and anodic reactions through adsorption on steel surface. Scanning electron microscopy was used to study the steel surface with and without inhibitor.