• 한국세라믹학회지
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• 제55권1호
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• pp.50-54
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• 2018

This study investigated the long-term durability of catalyst(Pd or Fe)-infiltrated solid oxide cells for $CO_2$/steam co-electrolysis. Fuel-electrode supported solid oxide cells with dimensions of $5{\times}5cm^2$ were fabricated, and palladium or iron was subsequently introduced via wet infiltration (as a form of PdO or FeO solution). The metallic catalysts were employed in the fuel-electrode to promote $CO_2$ reduction via reverse water gas shift reactions. The metal-precursor particles were well-dispersed on the fuel-electrode substrate, which formed a bimetallic alloy with Ni embedded on the substrate during high-temperature reduction processes. These planar cells were tested using a mixture of $H_2O$ and $CO_2$ to measure the electrochemical and gas-production stabilities during 350 h of co-electrolysis operations. The results confirmed that compared to the Fe-infiltrated cell, the Pd-infiltrated cell had higher stabilities for both electrochemical reactions and gas-production given its resistance to carbon deposition.

• 전기화학회지
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• 제22권3호
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• pp.104-111
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• 2019

금속 할로겐 페로브스카이트 (perovskite)는 우수한 전기적, 광학적 특성으로 인해 차세대 태양전지의 핵심 소재로 큰 주목을 받고 있다. 페로브스카이트 태양전지는 등장 이후 전례 없는 단기간 효율 향상을 보이며 현재 24% 이상의 인증된 광전 변환 효율을 달성하였지만, 대부분의 고성능 페로브스카이트 태양전지는 유독성 납 (Pb)을 기반으로 한 페로브스카이트를 사용한 것으로, 향후 상용화를 위해서는 납을 쓰지 않는 친환경 페로브스카이트 개발이 필수적이다. 본 글에서는 비납 페로브스카이트 물질 및 연구 동향에 대해서 소개하고자 한다.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.12-27
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• 2018

Supercapacitors (SCs) has gained an impressive concentration by the researchers due to its advantages such as high energy and power densities, long cyclic life, rapid charge-discharge rates, low maintenance and desirable safety. Hence it has been widely utilized in energy storage and conversion devices. Among the different components of SC, electrodes play a vital role in the performances of SCs. In this review, we present the recent advances in 2-D nanostructured metal nitrides, carbides, and phosphides based materials for SC electrodes. Finally, the electrochemical stability and designing approach for the future advancement of the electrode materials are also highlighted.

• Composites Research
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• 제34권6호
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• pp.345-349
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• 2021

The continued environmental pollution caused by fossil fuel consumption has prompted researchers around the world to develop environmentally friendly energy technologies. Electrochemical energy storage is the significant area of research in this development process, and the research significance of supercapacitors in this field is increasing. Herein, a simple electrodeposition synthetic route was explored to develop the MoP layered cathode material. The layered structure provided a highly ion-accessible surface for smooth and faster ion adsorption/desorption. After Fe was doped into MoP, the morphology of MoP changes and the electrochemical performance was significantly improved. Specific capacitance value of the binder-free FeMoP electrode was found to be 269 F g^-1 at 2 A g^-1 current density in 6 M aqueous KOH electrolyte. After adding Fe to MoP, an additional redox contribution was observed in the redox conversion from Fe³⁺ to Fe²⁺ redox pair, and the charge transfer kinetics of MoP was effectively improved. This research can provide guidance for the development of supercapacitor electrode materials through simple electrodeposition technology.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.72-80
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• 2004

국내의 가동 중지된 우라늄 변환시설의 해체 시 다량의 우라늄으로 오염되어 있는 금속성 폐기물의 재활용 또는 자체처분을 위한 제염기술로 중성염 전해액을 사용하는 전해제염 공정의 적용성을 평가하기 위하여 우라늄 변환시설 내부설비의 주 구성 재료인 SUS-304 및 Inconel-600에 대한 전기화학적 용해거동 연구를 수행하였다. 이를 위하여 중성염 전해질의 형태, 전해질의 농도, 전류밀도, 처리시간과 같은 전해제염 조건들이 금속 재료의 용해에 미치는 영향을 평가하였다. 모의 시편을 사용한 비방사성 전해용해 실험 결과를 근거로 실제 우라늄 변환시설로부터 인출한 $UO_2$, AUC (ammonium uranyl carbonate) 및 ADU (ammonium diuranate) 오염시편에 대해 $Na_2SO_4$및 $NaNO_3$ 중성염 용액에서 전해 제염실험을 수행하였으며, 오염물의 종류 및 오염 준위의 대소와는 관계없이 모든 시편에 대하여 10분 이내의 짧은 시간 내에 자체처분 기준치 이하로 $\beta$ 방사능 준위를 감소시킴으로써 본 중성염 전해제염이 매우 성공적임을 확인하였다.

• 전기화학회지
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• 제9권1호
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• pp.19-28
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• 2006

The phase-shift method for determining the Langmuir, Frumkin, and Temkin adsorption isotherms ($\theta_H\;vs.\;E$) of H for the cathodic $H_2$ evolution reaction (HER) at a Pt/0.1 M KOH solution interface has been proposed and verified using cyclic voltammetric, differential pulse voltammetric, and electrochemical impedance techniques. At the Pt/0.1 M KOH solution interface, the Langmuir and Temkin adsorption isotherms ($\theta_H\;vs.\;E$), the equilibrium constants ($K_H=2.9X10^{-4}mol^{-1}$ for the Langmuir and $K_H=2.9X10^{-3}\exp(-4.6\theta_H)mol^{-1}$ for the Temkin adsorption isotherm), the interaction parameters (g=0 far the Langmuir and g=4.6 for the Temkin adsorption isotherm), the rate of change of the standard free energy of $\theta_H\;with\;\theta_H$ (r=11.4 kJ $mol^{-1}$ for g=4.6), and the standard free energies (${\Delta}G_{ads}^{\circ}=20.2kJ\;mol^{-1}$ for $k_H=2.9\times10^{-4}mol^{-1}$, i.e., the Langmuir adsorption isotherm, and $16.7<{\Delta}G_\theta^{\circ}<23.6kJ\;mol^{-1}$ for $K_H=2.9\times10^{-3}\exp(-4.6\theta_H)mol^{-1}$ and $0.2<\theta_H<0.8$, i.e., the Temkin adsorption isotherm) of H for the cathodic HER are determined using the phase-shift method. At intermediate values of $\theta_H$, i.e., $0.2<\theta_H<0.8$, the Temkin adsorption isotherm ($\theta_H\;vs.\;E$) corresponding to the Langmuir adsorption isotherm ($\theta_H\;vs.\;E$), and vice versa, is readily determined using the constant conversion factors. The phase-shift method and constant conversion factors are useful and effective for determining the Langmuir, Frumkin, and Temkin adsorption isotherms of intermediates for sequential reactions and related electrode kinetic and thermodynamic data at electrode catalyst interfaces.

• 전기화학회지
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• 제19권2호
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• pp.39-44
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• 2016

연료전지에서 산소 환원 반응 (ORR)은 전체 반응에서 지배적인 역할을 한다. 또한 서로 다른 물질로 이루어진 막과 바인더 간의 낮은 호환성은 연료전지 효율을 크게 감소시킨다. 이러한 두 가지 문제점을 고려하여, 본 연구에서는 기존의 일반적인 Biphenol 대신 입체적 구조를 갖는 9,9_Bis(4-hydroxyphenyl) fluorine를 이용한 고분자를 합성하여 각각의 전극 바인더를 제조하였고, 이를 이용하여 각각의 나피온 막과 탄화수소 막 위에 스프레이 기법으로 MEA를 제조하여 전기화학적 성능 평가를 진행하였다. 그 결과 전류-전압 곡선에서의 0.6 V의 성능이 두 종류의 다른 막을 적용 했을 때 큰 차이를 보이지 않았으며, 탄화 수소 막의 타펠 기울기의 정도가 나피온 막에 비해 현저히 낮았다. 이를 통해 본 연구에서 적용된 아이오노머 바인더가 연료 전지성능 향상에 더 기여할 수 있을 것으로 판단 된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.86-86
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• 2012

The new approaches for silicon solar cell of new concept have been actively conducted. Especially, solar cells with wire array structured radial p-n junctions has attracted considerable attention due to the unique advantages of orthogonalizing the direction of light absorption and charge separation while allowing for improved light scattering and trapping. One-dimenstional semiconductor nano/micro structures should be fabricated for radial p-n junction solar cell. Most of silicon wire and/or pillar arrays have been fabricated by vapour-liquid-solid (VLS) growth because of its simple and cheap process. In the case of the VLS method has some weak points, that is, the incorporation of heavy metal catalysts into the growing silicon wire, the high temperature procedure. We have tried new approaches; one is electrochemical etching, the other is noble metal catalytic etching method to overcome those problems. In this talk, the silicon pillar formation will be characterized by investigating the parameters of the electrochemical etching process such as HF concentration ratio of electrolyte, current density, back contact material, temperature of the solution, and large pre-pattern size and pitch. In the noble metal catalytic etching processes, the effect of solution composition and thickness of metal catalyst on the etching rate and morphologies of silicon was investigated. Finally, radial p-n junction wire arrays were fabricated by spin on doping (phosphor), starting from chemical etched p-Si wire arrays. In/Ga eutectic metal was used for contact metal. The energy conversion efficiency of radial p-n junction solar cell is discussed.

• 한국물환경학회지
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• 제32권3호
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• pp.297-302
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• 2016

Microbial electrochemical technology (MET) has recently been studied to improve the efficiency of a traditional anaerobic digestion (AD). The purpose of this study was to investigate the impact of MET in the system when MET was combined with traditional AD (i.e., AD-MET). Electrodes used in the MET were Cu coated graphite electrodes. They were supplied with a voltage of 0.3 V. AD started to generate methane in 80 days. But AD-MET started to generate methane from the initial operation after the system started. It was observed that AD-MET reached steady state faster and produced higher methane yield than AD. During the steady state, the average daily methane productions in AD and AD-MET were 2.3L/d and 4.9L/d, respectively. Methane yields were 0.07-CH₄/g‧CODre in AD and 0.25L-CH₄/g‧CODre in AD-MET. In AD-MET, the production rates of total volatile fatty acids (TVFAs) and soluble chemical oxygen demand (SCOD) were 0.12 mg TVFAs/mg VS‧d and 0.35 mg SCOD/mg VS‧d, respectively. They were significantly (p < 0.05) higher than those in AD. However, the concentrations of residual TVFAs in both systems were not significantly (p > 0.05) different from each other, confirming that methane conversion in AD-MET was greater than that in AD.

• 한국전기전자재료학회논문지
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• 제24권4호
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• pp.333-339
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• 2011

In this work, electrochemical characteristics and optical transmittance of carbon nanotubes (CNTs) counter electrodes which had different amount of CNTs in CNTs slurries were analyzed. Two-step heat treatment processes were applied to achieve well-fabricated CNTs electrode. Three sets of CNTs electrodes and dye-sensitized solar cells (DSSCs) with CNTs counter electrodes were prepared. As the amount of CNTs increased, sheet resistance of CNTs electrode decreased. CNTs electrode with low sheet resistance had low electrochemical impedance and fast redox reaction. On the other hand, in case of CNTs counter electrode with low density of CNTs, performance of the dye-sensitized solar cell was improved due to its high optical transmittance. We found that the transmittance of CNTs counter electrode influence the performance of dye-sensitized solar cells.