• Journal of the Korean Electrochemical Society
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• v.17 no.3
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• pp.201-208
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• 2014

A Pt catalyst ($Pt/G_xC_y$) supported on the hybrid supporting materials composed of graphene oxide (GO) and carbon black (C) was fabricated using polyol method to improve the durability of electrocatalysts. The electrochemical performances measured by cyclic voltammograms using three-electrode system revealed that the properly designed $Pt/G_xC_y$ catalyst exhibited higher durability than that of Pt/C catalyst without sacrificing an electrocatalytic acivity. In the oxygen reduction reaction (ORR) performed in acid solution with the rotating disk electrode, the $Pt/G_xC_y$ catalyst showed greater mass and area-specific activity than those of Pt/C catalyst.

• Corrosion Science and Technology
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• v.4 no.1
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• pp.19-22
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• 2005

Two Au-Ag-Cu-Pd dental casting alloys (Au:12% and 20%) used. The test solutions used 0.9 % NaCl solution (isotonic sodium chloride solution), 0.9 % NaCl solution containing 1 % lactic acid, and 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_2S$. The surface of two samples in three sample solutions was not natural discoloration during one year. The alloy containing 12 % gold was easily alloyed and the composition was uniform comparing with the alloy containing 20 % gold. The rest potentials have not a little effect after three months. The kinds of metals could not definitely from the oxidation and reduction waves of metal on the cyclic voltammograms. The dissolutions of gold and palladium were 12 % Au sample in the 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_{2}S$. The pH of solution had an affect on dissolution of copper, and sulfur ion had an affect on dissolution of silver. The copper dissolved amount from 20 % gold sample was about 26 times comparing with that of 12 % gold sample in the 0.9 % solution containing 1 % lactic acid. Corrosion products were silver chloride and copper chloride in NaCl solution, and silver sulfide and copper sulfide in NaCl solution containing $Na_{2}S$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.571-583
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• 1996

The electrochemical behavior on electrographite and graphite foil electrode with porous surface in 0.5 M $K_{2}SO_{4}$ solution with 1 mM $[Fe(CN)_{6}]^{3-}/[Fe(CN)_{6}]^{4-}$ have been characterized by impedance spectroscopy. In cyclic voltammograms, relative high current according to structure of porous surface for graphite materials was represented, and indicated hgih double layer capacitance on graphite foil. The faraday-impedance and the change of impedance spectrum on both graphite materials were not remarkable during polarization by reaction of field transport. Chemical adsorption was represented on electrographite and was depended highly at anodic polarization.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1829-1833
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• 2012

Titania spheres were synthesized using binary ionic liquids to examine the electrocatalytic activity in acid solution. The morphology of $TiO_2$ particles was significantly different with the composition of ionic liquids. Among the binary ionic liquids, four set of mixtures led to the formation of $TiO_2$ sphere with various sizes. The morphology and structure of $TiO_2$ particles were characterized by XRD, $N_2$ physisoption and SEM analysis. All samples possessed an anatase phase after calcinations at $500^{\circ}C$. The structural properties of the samples were varied significantly with the morphology. In cyclic voltammograms, the morphology of $TiO_2$ spheres affected the electrocatalytic activity in water electrolysis. Among the samples, [Omim][$BF_4$]+[Hmim][$BF_4$] was the most effective ionic liquid to synthesize $TiO_2$ sphere with optimum morphology showing the highest electocatalytic performance.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2343-2347
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• 2013

In this work, manganese dioxide ($Mn_3O_4$)/carbon black (CB) composites (Mn-CBs) were prepared by an in situ coating method as electrical fillers and the effect of the Mn-CBs on the electrical performance of activated carbon (AC)-based electrodes was investigated. Structural features of Mn-CBs produced via in situ coating using a $KMnO_4$ solution were confirmed by XRD and TEM images. The electrical performances, including cv curves, charge-discharge behaviors, and specific capacitance of the ACs/Mn-CBs, were determined by cyclic voltammograms. It was found that the composites of $Mn_3O_4$ and CBs were successfully formed by in situ coating method. ACs/Mn-CBs showed higher electrical performance than that of AC electrodes fabricated with conventional CBs due to the pesudocapacitance reaction of manganese oxides in the aqueous electrolyte. Consequently, it is anticipated that the incorporation of $Mn_3O_4$ into CBs could facilitate the utilization of CBs as electrical filler, leading to enhanced electrochemical performance of AC electrodes for supercapacitors.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.34-35
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• 2008

We investigated the effects of Pt nano electrodeposits on the corrosion of carbon substrate in an acidic solution. The electrodes for experiments were prepared by electrodepositing Pt on carbon substrate in a solution of 5 mM $H_2PtCl_6$ and 0.5 M $H_2SO_4$ using pulse deposition technique. In cyclic voltammograms for the carbon electrodes with and without Pt nano electrodeposits, total anodic current including both currents from oxygen evolution reaction and carbon corrosion increased abruptly above a critical potential. In addition, the critical potential of the carbon electrodes with Pt nano electrodeposits was lower than that of bare carbon electrode. This phenomenon was more prominent at $75^{\circ}C$ than $25^{\circ}C$. In potentiostatic experiments, the current transients and the corresponding power spectral density increased with increasing the applied potential for the electrodes. Furthermore, the current transients for the carbon electrodes with Pt nano electrodeposits were much higher than those for the bare carbon substrate. This indicates that the corrosion of carbon substrate can be highly accelerated by Pt nano electrodeposits.

• Analytical Science and Technology
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• v.16 no.3
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• pp.198-205
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• 2003

The ammonium salt of nitrosophenylhydroxylamine, called cupferron, has been used not only as the ligand but also as an oxidizing agent for adsorptive catalytic stripping voltammetry (AdCtSV). Cyclic voltammetry was used for elucidating the electrochemical behavior of Os-cupferron complex in 1 mM phosphate buffer. The optimal conditions for osmium analysis were found to be 1 mM phosphate buffer solution (pH 6.0) containing 0.1 mM cupferron at scan rate of 100 mV/s. By using the plot of reduction peak currents of linear scan voltammograms vs. osmium concentration, the detection limit was $1.0{\times}10^{-7}M$.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1363-1364
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• 2007

The composites such as Sn-CNTs, $SnSb_{0.5}$-CNTs and $CoSb_3$-CNTs have attracted much attention in the past years owing to their good overall properties. In these samples, intermetallic compounds show high specific capacities. Recently, interest in metal oxides such as $Al_{2}O_{3}$, MgO and $TiO_2$ has been largely stimulated by the realization that they can improve the cycling stability of the Li-ion battery electrodes. The reversible capacity of the $TiO_2$/CNTs composite reaches 168 mAh $g^{-1}$ at the first cycle and remains almost constant during long-term cycling. In this study, a nanocomposite of $TiO_2$/CNTs was prepared by sol-gel method and its electrochemical properties as anode materials for Li-ion batteries were studied by galvanostatic cycling, cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS).

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.11a
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• pp.133-138
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• 2004

Proton exchange membrane fuel cell (PEMFC) is considered as a clean and efficient energy conversion det ice for mobile and stationary applications. Anions all the components of the PEMFC, the interface between the electrolyte ,and electrode catalyst plays an important role in determining tile cell performance since the electrochemical reactions take place at the interface in contact with tile reactant gases. Therefore, to increase the interface area and obtain a high-performance PEMFC, surface of the electrolyte membrane was roughened by Ar$^{+}$ beam bombardment. The results imply that by modifying surface of the electrolyte membrane, platinum loading can be reduced significantly without performance loss. To optimize the surface treatment condition, effects of ion dose density on characteristics of the membrane/electrode interface were examined by measuring the cell performance, impedance spectroscopy, and cyclic voltammograms. Surface of the modified membranes were characterized using scanning electron microscopy and FT-IR.R.

• Bulletin of the Korean Chemical Society
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• v.11 no.3
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• pp.200-205
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• 1990

Chemically modified electrodes(CMEs), based on 2-imino-1-cyclopentane-dithiocarboxylic acid (icdc) containing carbon paste, have been characterized using cyclic voltammetric techniques. Ag(I) was chemically deposited on the CMEs, and voltammograms were obtained with the electrode in a separate buffer solution. The CME surface can be regenerated with exposure to acid and reused for deposition. In 10 deposition/measurement/regenerate cycles, the linear response have been reproduced up to $1{\times}10^{-6}$ M in linear sweep voltammetry and 1${\times}$10-8 M in differential pulse voltammetry with relative standard deviation of 5.2% and 12.4%, respectiveiy. The sensitivity increased with deposition time and scanning rate, and detection limit was $1{\times}10^{-7}M\;and\;1{\times}10^{-9}M$ at 20 minutes deposition in the linear sweep voltammetry and differential pulse voltammetry, respectively. The presence of some metal ions does not influence the silver ion response. Satisfactory results were obtained for the analysis of the silver ion for a variety of reference materials without interference of Hg ion at the condition of pH = 5-6.