• 대한화학회지
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• 제23권3호
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• pp.180-185
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• 1979

각종 陰極, 卽 Ti, Zr, Ni, Pt, Cu, Ag, Au, Zn, Hg, Pb 및 흑연의 사용으로 2-butyne-1, 4-diol (BID)로부터 2-butene-1,4-diol (BED)까지의 電氣化學的 還元擧動에 관하여 연구하였다. IB族 金屬을 陰極으로 사용한 陰極分極曲線은 알칼리용액중에서 BID에 對해 한개의 還元波가 생기나 BED의 경우는 지지전해질내에서와 마찬가지로 還元波가 생기지 않았다. 고로 BID환원반응에 가장 적당한 陰極은 Cu, Ag, Au임을 알았다. 알칼리性 BID용액에서 銀電極을 사용한 電位走査法에서 peak電流는 電位走査速度의 제곱근과 BID농도에 比例하였다. 限界電流의 對數와 絶對溫度의 逆數의 관계로부터 구한 BID의 活性化에너지는 3.75kcal/mole였다. 고로 알칼리용액중 銀電極을 사용한 BID의 還元電流는 自己擴散에 의한 擴散電流임을 알았다.

• 한국재료학회지
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• 제19권12호
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• pp.667-673
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• 2009

The electrocatalytic characteristics of oxygen reduction reaction of the $PtxM_{(1-x)}$ (M = Co, Cu, Ni) supported on multi-walled carbon nanotubes (MWNTs) have been evaluated in a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The $Pt_xM_{(1-x)}$/MWNTs catalysts with a Pt : M atomic ratio of about 3 : 1 were synthesized and applied to the cathode of PEMFC. The crystalline structure and morphology images of the $Pt_xM_{(1-x)}$ particles were characterized by X-ray diffraction and transmission electron microscopy, respectively. The results showed that the crystalline structure of the Pt alloy particles in Pt/MWNTs and $Pt_xM_{(1-x)}$/MWNTs catalysts are seen as FCC, and synthesized $Pt_xM_{(1-x)}$ crystals have lattice parameters smaller than the pure Pt crystal. According to the electrochemical surface area (ESA) calculated with cyclic voltammetry analysis, $Pt_{0.77}Co_{0.23}$/MWNTs catalyst has higher ESA than the other catalysts. The evaluation of a unit cell test using Pt/MWNTs or $Pt_xM_{(1-x)}$/MWNTs as the cathode catalysts demonstrated higher cell performance than did a commercial Pt/C catalyst. Among the MWNTs-supported Pt and $Pt_xM_{(1-x)}$ (M = Co, Cu, Ni) catalysts, the $Pt_{0.77}Co_{0.23}$/MWNTs shows the highest performance with the cathode catalyst of PEMFC because they had the largest ESA.

• 한국재료학회지
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• 제14권10호
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• pp.719-724
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• 2004

Production of fine tantalum powder by calciothermic reduction of tantalum oxides ($Ta_{2}O_5$) pellet through an electronically mediated reaction (EMR) has been investigated. $Ta_{2}O_5$ pellet feed and reductant calcium-nickel (Ca-Ni) alloy were charged into electronically isolated locations in a molten $CaCl_2$ bath. The current flow through an external path between the feed (cathode) and reductant (anode) locations was monitored. The current approximately 4.7A was measured during the reaction in the external circuit connecting cathode and anode location. Tantalum powder with approximately 99 $mass\%$ purity was readily obtained after each experiment. Tantalum powder by EMR using $Ta_{2}O_5$ pellet feed was fine compared with that of metal powder by metallothermic reduction and EMR using $Ta_{2}O_5$ powder feed.

• 한국세라믹학회지
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• 제53권3호
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• pp.306-311
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• 2016

Li-air batteries have received much attention due to their superior theoretical energy density. However, their sluggish kinetics on the cathode side is considered the main barrier to high performance. The rational design of electrode catalysts with high activity is therefore an important challenge. To solve this issue, we performed density functional theory (DFT) calculations to analyze the adsorption behavior of the $LiO_2$ molecule, which is considered to be a key intermediate in both the Li-oxygen reduction reaction (ORR) and the evolution reaction (OER). Specifically, to use the activity descriptor approach, the $LiO_2$ adsorption energy, which has previously been demonstrated to be a reliable descriptor of the cathode reaction in Li-air batteries, was calculated on $LaB_{1-x}B^{\prime}_xO_3$(001) (B, B' = Mn, Fe, Co, and Ni, x = 0.0, 0.5). Our fast screening results showed that $LaMnO_3$, $LaMn_{0.5}Fe_{0.5}O_3$, or $LaFeO_3$ would be good candidate catalysts. We believe that our results will provide a way to more efficiently develop new cathode materials for Li-air batteries.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.337-337
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• 2004

As one of researches for the P ＆ T purposes, a basic experiment on the recovery of actinide elements from the mixture with rare earth elements by means of electrorefining using a liquid cadmium cathode in the LiCl-KC1 eutectic melt was carried out. In order to examine the behaviors of electrodeposition of metal ions on a liquid electrode, recovery experiments of rare earth metals resulting from forming electrodeposits were performed by a galvanostatic electrolysis method at various current densities. A cyclic voltammetric technique was applied to determine reduction-oxidation potential of each metal element in the melt and to detect the changes of the multi component melt composition for on-line monitoring. Also, a collaboration study with RIAR was completed to test the preliminary feasibility on a recovery of actinide elements from the mixture with rare earth elements using a liquid cadmium cathode and actinide metals. Experimental results showed that the ratio of actinides to rare earths, 9: 0.5∼1 led to the rare earth content of about 5∼10 wt% in the deposit.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1038-1041
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• 2002

We have investigated the effects of cathode in organic light-emitting diodes of ITO/TPD/$Alq_3$/Cathodes(Al, LiF/Al, Ca/Al, and LiAl) by measuring current-voltage-luminance characteristics. The device with cathodes other than Al cathode shows the efficiency by an oder of one compared with Al cathode only. This improvement is due to a reduction of barrier height in cathode side.

• 방사성폐기물학회지
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• 제18권4호
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• pp.421-437
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• 2020

This study provides an assessment on a proposed method for separation of cesium, strontium, and barium using electrochemical reduction at a liquid bismuth cathode in LiCl-KCl eutectic salt, investigated via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS). CV studies were performed at temperatures of 723-823 K and concentrations of the target species up to 4.0wt%. Redox reactions occurring during potential sweeps were observed. Concentration of BaCl2 in the salt did not seem to influence the diffusivity in the studied concentration range up to 4.0wt%. The presence of strontium in the system affected the redox reaction of lithium; however, there were no distinguishable redox peaks that could be measured. Impedance spectra obtained from EIS methods were used to calculate the exchange current densities of the electroactive active redox couple at the bismuth cathode. Results show the rate-controlling step in deposition to be the mass transport of Cs+ ions from the bulk salt to the cathode surface layer. Results from SEM-EDS suggest that Cs-Bi and Sr-Bi intermetallics from LiCl-KCl salt are not thermodynamically favorable.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.644-652
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• 2022

During the pyroprocessing operation, various signals can be collected by process monitoring (PM). These signals are utilized to diagnose process states. In this study, feasibility of using PM for nuclear safeguards of electrorefining operation was examined based on the use of machine learning for detecting off-normal operations. The off-normal operation, in this study, is defined as co-deposition of key elements through reduction on cathode. The monitored process signal selected for PM was cathode potential. The necessary data were produced through electrodeposition experiments in a laboratory molten salt system. Model-based cathodic surface area data were also generated and used to support model development. Computer models for classification were developed using a series of recurrent neural network architectures. The concept of transfer learning was also employed by combining pre-training and fine-tuning to minimize data requirement for training. The resulting models were found to classify the normal and the off-normal operation states with a 95% accuracy. With the availability of more process data, the approach is expected to have higher reliability.

• 한국표면공학회지
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• 제49권3호
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• pp.316-321
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• 2016

To study emission characteristics for dual-emission tandem organic light emitting display (OLED), we fabricated blue fluorescent OLED according to thickness variation of $MoO_x$ as charge generation layer and Al as cathode. The bottom emission characteristics of OLED with $MoO_x$ 2, 3, 5 nm thickness showed threshold voltage of 9, 7, 9 V, maximum current emission efficiency of 19.32, 23.18, 15.44 cd/A and luminance of $1,000cd/m^2$ at applied voltage of 17.6, 13.2, 16.5 V, respectively. The top emission characteristics of OLED with $MoO_x$ 2, 3, 5 nm thickness indicated threshold voltage of 13, 10, 13 V, maximum current emission efficiency of 0.17, 0.23, 0.16 cd/A and luminance of $50cd/m^2$ at applied voltage of 22.6, 16.5, 20.1 V, respectively. In case of thicker or thinner than $MoO_x$ of 3 nm, the emission characteristics were decreased because of mismatching of electron and hole in emission layer. The bottom emission characteristics of OLED with Al 15, 20, 25 nm thickness showed threshold voltage of 8, 8, 7 V, maximum current emission efficiency of 18.42, 22.98, 23.18 cd/A and luminance of $1000cd/m^2$ at applied voltage of 16.2, 13.9, 13.2 V, respectively. The reduction of threshold voltage and increase of maximum current emission efficiency are caused by the increase of current injection according to increase of Al cathode thickness. The top emission characteristics of OLED with Al 15, 20, 25 nm thickness indicated threshold voltage of 7, 7, 8 V, maximum emission luminance of 371, 211, $170cd/m^2$, respectively. The top emission OLED of Al cathode with 15 nm thickness showed maximum luminance and it decreased at thickness of 20 nm. These phenomena are caused by the decrease of intensity of emitted light by reduction of optical transmittance according to increase of Al cathode thickness.

• 자원리싸이클링
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• 제33권1호
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• pp.15-21
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• 2024

전기차용 리튬이온배터리의 수요가 증가함에 따라 향후 발생할 폐리튬이온배터리 중의 유가금속 회수가 필요하다. 본 연구에서는 리튬이온배터리의 NCM계 양극재를 수소환원과 수침출에 의해 리튬을 수산화리튬으로 회수할 때의 회수율에 미치는 반응온도의 영향을 조사하였다. 반응온도가 상승함에 따라 수소에 의한 NiO, CoO의 환원에 의해 무게 감소율이 반응초기부터 급격하게 증가하였으며 동시에 H₂O 발생량도 증가하였다. 602 ℃ 이상에서는 양극재 중의 Ni, Co가 전부 환원되어 금속상으로 존재하였다. 그리고 수소환원 온도의 상승과 함께 Li 회수률도 증가하였으나 704 ℃ 이상에서는 약 92 % 이상의 유사한 수준을 나타내었다. 따라서 폐Li이온 배터리의 전처리로 수소환원하는 것에 의해 리튬만 사전에 회수하고 잔사를 재처리하면 효율적으로 유가금속을 분리하여 회수할 수 있을 것으로 기대된다.