• Journal of Surface Science and Engineering
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• v.43 no.4
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• pp.180-186
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• 2010

$TiO_2$ nanotubes were formed on Ti by anodizing in 1 M $H_3PO_4$ + 0.3 M HF and 0.1 M $NH_4F$ + 2% $H_2O$ in ethylene glycol, and their surface and cross-sectional morphologies were observed using FE-SEM as a function of anodizing time and applied voltage. The cross-section of the $TiO_2$ nanotubes was readily observed from the small pieces of nanotubes remaining near the scratch lines after scratching of the anodized surface. $TiO_2$ nanotubes was observed to grow faster and thicker in non-aqueous solution than in aqueous solution. Diameter of $TiO_2$ nanotubes was proportional to the applied voltage, irrespective of the type of the electrolyte, and it is recommended to use non-aqueous solutions for the preparation of larger diameter of $TiO_2$ nanotubes.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.282-285
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• 2009

This study presents preparation and characterization of composite membranes based on ionic liquids. The ionic liquids act as water in sulfonated membranes. On the behalf of ionic conduction through ionic liquid inside the membranes, non-aqueous membranes showed Arrenhius dependence on temperature with no external humidification. It was implied that hopping mechanism of proton was dominant in the ionic liquid based membranes. In addition, small angle X-ray (SAXS) studies provided the information on morphology of ionic clusters formed by the interaction between sulfonic acid groups of the polymers and ionic liquids. The SAXS spectra showed matrix peaks, ionomer peaks and Prodo's law for Nafion based composite membranes and only matrix peaks for hydrocarbon based ones. However, ionic conductivity and atomic force microscopy (AFM) images showed the clear formation of ionic clusters of the hydrocarbon based composite membranes. It implies for ionic liquid based high temperature membranes that it is important to use sulfonated polymers as solid matrix of ionic liquid which can form clear ionic clusters in SAXS spectra.

• Journal of the Korean Electrochemical Society
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• v.6 no.2
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• pp.141-144
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• 2003

Proton conducting polymeric gels as the electrolytes of electrochemical capacitors have been prepared by two different methods: 1) swelling a polymethacrylate-based polymer matrix in aqueous solutions of inorganic and organic acids, and 2) polymerizing complexes of anhydrous acids and prepolymers with organic plasticizer. The FT-IR spectra strongly suggest that the carbonyl groups in the polymer matrix interact with protons from the doped acids. High ionic (proton) conductivity in the range of $6\times10^{-4}-4\times10^{-2}\;S\;cm^{-1}$ was obtained at room temperature for the aqueous gels. The non-aqueous polymer complexes showed rather low ionic conductivity, but it was about $10^{-3}\;S\;cm^{-1}\;at\;70^{\circ}C$ for the $H_3PO_4$ doped polymer electrolyte. The mechanisms of ion (proton) conduction in the polymeric systems are discussed.

• Applied Microscopy
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• v.23 no.2
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• pp.1-10
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• 1993

The effect of electrolyte on the extraction replicas of the precipiates in 3% Si steel was investigated. Three Kinds of electrolyte, 2% Nital solution (2% nitric acid+methanol; acid solution),, Sodium Citrate solution (5% sodiumcitrate+1% KBr+0.5KI+$H_{2}O$; aqueous neutral solution) and 10% AA solution (10% acetylacetone+ 1% tetramethylammoniumchloride+methanol; non-aqueous neutral solution), were compared. The preciptiates in 3% Si steel were dissolved in 2% Nital, but they were not dissolved in the Sodium Citrate and 10% AA solution. In Sodium Citrate solution, however, large second artifacts were introduced during sample preparation. Therefore 10% AA solution was found to be most useful for the preparation of extraction replica. The electrolysis condition of a matrix and precipitates were also checked by the measurement of potential-current curve in 10% AA solution. The matrix was electrolyzed at -400mV with respect to SCE(Saturated Calomel Electrode). In contrats precipitates were electrolyzed above 300mV. Precipitates were respected to be stable in 10% AA solution in the range of $-380mV{\sim}-300mV$ usually used to prepare extraction replicas.

• Journal of Environmental Health Sciences
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• v.40 no.2
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• pp.137-146
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• 2014

Objectives: Feasibility of electrochemical oxidation of the aqueous non-biodegradable wastewater such as cationic dye Rhodamine B (RhB) has been investigated in an electrochemical reactor with solid polymer electrolyte (SPE). Methods: Nafion 117 cationic exchange membrane as SPE has been used. Anode/Nafion/cathode sandwiches were constructed by sandwiching Nafion between two dimensionally stable anodes (JP202 electrode). Experiments were conducted to examine the effects of applied current (0.5~2.0 A), supporting electrolyte type (0.2 N NaCl, $Na_2SO_4$, and 1.0 g/L NaCl), initial RhB concentration (2.5~30.0 mg/L) on RhB and COD degradation and $UV_{254}$ absorbance. Results: Experimental results showed that an increase of applied current in electrolysis reaction with solid polymer electrolyte has resulted in the increase of RhB and $UV_{254}$ degradation. Performance for RhB degradation by electrolyte type was best with NaCl 0.2 N followed by SPE, and $Na_2SO_4$. However, the decrease of $UV_{254}$ absorbance of RhB was different from RhB degradation: SPE > NaCl 0.2 N > $Na_2SO_4$. RhB and $UV_{254}$ absorbance decreased linearly with time regardless of the initial concentration. The initial RhB and COD degradation in electrolysis reaction using SPE showed a pseudo-first order kinetics and rate constants were 0.0617 ($R^2=0.9843$) and 0.0216 ($R^2=0.9776$), respectively. Conclusions: Degradation of RhB in the electrochemical reactor with SPE can be achieved applying electrochemical oxidation. Supporting electrolyte has no positive effect on the final $UV_{254}$ absorbance and COD degradation. Mineralization of COD may take a relatively longer time than that of the RhB degradation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.93-93
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• 2008

니켈도금은 각종 소지 상에 직접적이고 밀착성이 양호하고, 변색이 적고 방청력이 크며, 경도, 내식성, 내마모성 및 유연성이 우수하다. 또한 최근 활발히 진행되고 있는 광촉매 연구에 $TiO_2$는 우수한 광화학적 안정성, 효과적인 전하분리, 높은 산화 환원력 및 상업적 적용성을 갖기 때문에 니켈도금용액에 $TiO_2$를 첨가하며 복합도금을 행함으로써 니켈이 가지고 있는 기존의 우수한 특성에 $TiO_2$의 광분해 효과를 부과시킴 으로써 그 특성이 한층 더 향상되는 것을 알수있다. 본 연구에서는 수용액전해질과 비수용액 전해질에서의 Ni-$TiO_2$ 복합도금의 특성을 비교 분석해보았다. 동전위(Potentiodynamic)실험 및 순환전위(Cyclic Voltammetry)실험을 하였으며, 도금층의 특성 및 두께는 OM,SEM을 이용하여 분석하였다. 또한 복합도금 촉매 전극에 의한 광분해 효과를 보기 위해서 UV램프를 이용하여 분석하였다.

• Journal of Surface Science and Engineering
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• v.35 no.1
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• pp.17-32
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• 2002

Electroplating methods by molten salts and non-aqueous melts were employed for aluminium coating on STS 316L stainless steel. After coated with Ni or non-coated surface on stainless steel, Al pulse plating was carried out in two different types of electrolytes at room temperature. The Al layer from $AlCl_3$-TMPAC melts could not obtain appreciable thickness for engineering application due to chemical reactions between deposits and moisture of air. However, The Al coating by pulse plating in the Ethylbenzene-Toluene-$AlBr_3$ systems was found to be solid coating layer with a few $\mu\textrm{m}$ scale. The conductivity of Ethylbenzene-Toluene-$AlBr_3$ electrolyte was as functions of time and agitation. By seven days exposure after mixing of the electrolyte, Al-deposited layer shows uniform and near by pore-free with high current density (higher than 30mA/$\textrm{cm}^2$). The roughness and imperfection of coating layer were decreased with a increasing agitation speed. It was found that the optimum condition for the Al pulse plating on the 316L stainless steel was a 400mA peak current, duty cycle, $t_{on}$ $t_{ off}$=3ms/1ms, and a current density of 30mA/$\textrm{cm}^2$.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.291-295
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• 2007

The oxidation treatment of needle cokes with 70 wt% of nitric acid and sodium chlorate ($NaClO_3$) was attempted to achieve an electrochemically active material with a large capacitance. The structure of needle cokes was changed to graphite oxide after oxidation treatment of needle cokes with acidic solution having the composition ratio, $NaClO_3$/needle cokes, of 7.5, and the inter-layer distance of the oxidized needle cokes was extended to $6.9{\AA}$with increasing oxygen content. On the other hand, the electrochemical performance of oxidized needle cokes as a polarized electrode for an Electric Double Layer Capacitor (EDLC) was examined with an electrolyte of 1.2 M $TEABF_4$ (tetraethylammonium tetrafluoroborate) and $TEABF_4$ (triethylmethylammonium tetrafluoroborate) in acetonitrile. The capacitor cell using 1.2 M $TEABF_4$/acetonitrile has exhibited smaller electric resistance of $0.05{\Omega}$, and larger capacitance per weight and volume of 32.0 F/g and 25.5 F/mL at the two-electrode system in the potential range 0~2.5 V than that of the capacitor cell using $TEABF_4$. The observed electrochemical performance was discussed with the correlation between the inter-layer distance in graphite oxide structure and the anionic size of electrolyte.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.21-26
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• 2022

Zinc is emerging as a environment-friendly plating material to replace cadmium, which is harmful to the human body, to prevent hydrogen gas penetration or release from metal materials. Electroplating of Zn and Zn alloys, which is usually performed in an aqueous acidic atmosphere, has disadvantages such as low coulombic efficiency, corrosion, and hydrogen release, resulting in industrial use difficult. In this study, a deep-eutectic solvent was synthesized using choline chloride and ethylene glycol. Using this as a solvent, an electrolyte for Zn plating was prepared, and then zinc was plated on the STS 304 substrate. The surface microstructure and roughness were observed using SEM and AFM. The crystal structure of the electro-plated film was analyzed using XRD. Finally, the preventing effects of hydrogen release through Zn-based deep-eutectic plating on the STS 304 substrate were compared with the uncoated substrate.

• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.159-165
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• 2009

The synthesis of 2-amino-5-substituted-1,3,4-oxadiazoles 4 were carried out from the electrooxidation of semicarbazone 3 at the platinum electrode under controlled potential electrolysis in an undivided cell. This is an environmentally benign method in the field of synthetic organic chemistry. The non-aqueous solvents acetic acid and acetonitrile and a supporting electrolyte lithium perchlorate were used for the electrolysis in the electrooxidation. The products were structurally charecterised by IR, $^1H$-NMR, $^{13}C$-NMR and elemental analysis.