• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.522-526
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• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

• Clean Technology
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• v.19 no.4
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• pp.410-415
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• 2013

The supercapacitors were fabricated using silver (Ag) nano paste and activated carbon paste on the polyimide (PI) film and 5% potassium polyacrylate (PAAK) was used for gel electrolyte. In this paper, the current collector film and the electrode film were fabricated using screen printing. The thickness of printed silver paste was $7.3{\mu}m$ and the sheet resistance has the range of $5-7m{\Omega}/square$. An activated carbon with a surface area of $1,968m^2/g$, an electronic conducting agent (SUPER P, TIMCAL) and poly (4-vinylphenol) were mixed in 2-(2-buthoxyethoxy) ethyl acetate (BCA) with a ratio of 7:1:3 to fabricate the electrode paste. To analyze electrochemical characteristics, cyclic voltammetry was performed to evaluate the stability of the devices under the voltage range of -0.5-0.5 V. The calculated specific capacitances were 44.04 and 8.62 F/g for 10 and 500 mV/s scan rates, respectively.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.421-426
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• 2016

In this report, polyoxometalte (POM)-doped polypyrrole (Ppy) was deposited on surface of three-dimensional carbon cloth (CC) using an electrodeposition method and its pseudocapacitive behavior was investigated using cyclic voltammetry and galvanostatic charge-discharge. The POM-Ppy coating was thin and conformal which can be controlled by electrodeposition time. As-prepared POM-Ppy/CC was characterized using scanning electron microscope and energy-dispersive X-ray spectroscopy. The unique 3D nanocomposite structure of POM-Ppy/CC was capable of delivering excellent charge storage performances: a high areal capacitance ($561mF/cm^2$), a high rate capability (85%), and a good cycling performance (97% retention).

• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.81-85
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• 2015

A method for degradation of the perchlorate anion ($ClO{_4}^-$) has been studied using electrochemically generated zero-valent iron (ZVI) deposited on a porous carbon electrode. The first strategy of this study is to produce the ZVI via the electrochemical reduction of iron (II) on a porous carbon electrode coated with a conducting polymer, instead of employing expensive $NaBH_4$. The present method produced well distributed ZVI on conducting polymer (polypyrrole thin film) and increased surface area. ZVI surface can be regenerated easily for successive reduction. The second strategy is to apply a mild reducing condition (-0.3 V) to enhance the efficiency of the degradation of perchlorate with ZVI without the evolution of hydrogen. The electrochemically generated ZVI nanoparticles may offer an alternative means for the complete destruction perchlorate without evolution of hydrogen in water with high efficiency and at low cost.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.814-819
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• 2010

Porous carbon electrodes with wooden materials are manufactured by molding carbonized wood powder. Electrical properties of the interface for electrolyte and porous carbon electrode are investigated from viewpoint of NaCl electrolyte concentration, capacitance and complex impedance. Density of porous carbon materials is 0.47~0.61 g/$cm^3$. NaCl electrolytic absorptance of the porous carbon materials is 5~30%. As the electrolyte concentration increased, capacitance is increased and electric resistance is decrease with electric double layer effect of the interface. The electric current of the porous carbon electrode compared in the copper and the high density carbon electrode was improved on a large scale, due to a increase in surface area. The circuit current increased as the distance between of the porous carbon electrode and the zinc electrode decreased, due to increase in electric field. Experimental results indicated that the current properties of galvanic cell could be improved by using porous carbon electrode.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.105-111
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• 1999

This paper presents experimental results on the electrical properties of hydrogenated amorphous carbon films(a-C:H) prepared by PECVD. DC conductance of a-C:H was measured as a function of temperatures in the range of 100 to 423K. We studied two a-C:H films: one was well explained by the Mott's Variable Range Hopping(VRH) rule, but the other sample did not follow it. However, the conduction data of second sample were well fitted to Shimakawa's Multi-Phonon Hopping(MPH) model according to which conductivity is proportional to $T^M$ with m=15-17. but, in our samples, m was 10-12. Also a-C:H showed several bias effects like relaxation of conductance, bias-dependent conductance and the change of conductance slope in 1n(${\sigma}{\sqrt{T}}$) vs. $T^{1/4}$ plot. In this study we interpret these data by bias-dependent detrapping model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.11
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• pp.725-728
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• 2016

We investigated the characterizations of carbon films fabricated by dual magnetron sputtering under various film thickness for the electrodes in TCO-less DSSC (dye-sensitized solar cells). Carbon films prepared at various conditions were exhibited smooth and uniform surfaces without defects. Also, the rms surface roughness of carbon films was decreased from 2.25 nm to 1.0 nm with the increase of film thickness. The sheet resistance as the electrical properties are improved from $11.2{\times}10^{-3}$ to $2.28{\times}10^{-3}$ with the increase of film thickness. In the results, the performance of TCO-less DSSC critically depended on the film thickness of working electrodes, indicating the conductivity of carbon films.

• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.13-17
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• 2003

Cryogel and aerogel Pt-Ru/C were synthesized by the sol-gel process for the electrooxidation of methanol. From XRD analysis, it was found that the catalysts had highly dispersed Pt-Ru alloys on carbon support although high temperature treatments have been conducted. Electrocatalytic activities of 3 type aerogel catalysts were investigated in half cell experiments by cyclic voltammetry. Among them, Phloroglucinol-Formaldehyde(PF) type catalyst shows the highest activity. From the results of deactivation test for each catalysts, the aerogel catalysts are found to have excellent durability compared with those prepared by colloidal method.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.131-141
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• 2009

The conversion of carbon dioxide to value-added compounds has been attracted to solve the environmental problems due to the climate change caused by greenhouse effect in addition to recycle the abundant and renewable carbon source. For utilizing carbon dioxide to useful compounds, the development of catalysts and optimization of experimental conditions are indispensable since carbon dioxide is the most stable one among carbon compounds and the a certain amount of energy is required for the carbon dioxide conversion. The technologies developed for the electrochemical carbon dioxide conversion were reviewed in terms of electrocatalyst which can be electrode material, inorganic complex, and enzyme. This field should be developed further since no good catalyst having selectivity, efficiency, and stability all together.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.289-289
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• 2010

나노섬유는 지름이 수십에서 수백 나노미터(1나노미터=10억분의1m)에 불과한 초극세 물질로 비표면적이 매우 크고[1], 제작이 간편하여, 사용되어지는 고분자의 종류에 따라 에너지 환경 의료 관련 분야에서 전극소재 필터재 피복재 인공 피부등 다양한 분야에서의 활용이 가능하여 전 세계적으로 연구개발이 활발하게 이루어지고 있다. 그러나 그 자체만으로 응용하기에는 그 기계적 전기적 특성의 한계 때문에 응용의 다양성에 제약을 받고 있다. 그러나 그 자체만으로 응용하기에는 그 기계적 열적 전기적 특성을 가진 탄소나노튜브를 첨가한 복합나노섬유에 의해 그 응용영역의 한계를 넓혀가고 있다.[2] 본 연구에서는 전도성 고분자인 polymethyl methacrylate (PMMA)에 multi-walled carbon nanotubes (MWCNTs)를 첨가한 복합나노섬유를 전기방사법(electrospinning method)을 통해서 제조하였다. [2~3] CNTs 첨가농도에 따른 제조된 복합나노섬유의 형상변화와 섬유내의 CNTs 배열상태를 각각 주사전자 현미경(scanning electron microscope: SEM)과 투과전자현미경(transmission electron microscope: TEM)을 이용하여 관찰하였다. 또한, 복합나노섬유의 광학 특성 변화를 CNTs 첨가농도에 따라서 FT-IR과 Raman spectroscopy등을 이용하여 조사하였으며, 나노섬유의 tensile strength의 측정을 통해 CNTs 함량에 따른 기계적 특성 변화를 분석하였다.