• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.436-442
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• 2014

$LaCoO_3$ powders synthesized by Pechini process were pulverized by planetary ball-milling to decrease particle size and characterized as a catalyst in alkaline solution for oxygen reduction and evolution reaction (ORR & OER). The changes of physical properties, such as particle size distribution, surface area and electric conductivity, were analyzed as a function of ball-milling time. Also, the variations of the crystal structure and surface morphology of ball-milled powders were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemically catalytic activities of the intrinsic $LaCoO_3$ powders decreased with increasing ball-milling time, but their electrochemical performance as an electrode improved by the increase of the surface area of the powder.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.378-385
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• 2014

In this research, we investigate electrical performance and electrochemical properties of graphene supported Pt (Pt/G) and PtM (M = Ni and Y) alloy catalysts (PtM/Gs) that are synthesized by modified polyol method. With the PtM/Gs that are adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with one another. Their particle size, particle distribution and electrochemically active surface (EAS) area are measured by TEM and cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and rotating ring-disk electrode and (ii) PEMFC single cell tests are used. The TEM and CV measurements demonstrate particle size and EAS of PtM/Gs are compatible with those of Pt/G. In case of PtNi/G, its half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production % are excellent. Based on data obtained by half-cell test, when PEMFC singlecell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing PtNi/G are better than those employing Pt/G. Conclusively, PtNi/Gs synthesized by modified polyol shows better ORR catalytic activity and PEMFC performance than other catalysts.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.295-298
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• 2000

Vanadate glasses in the Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$ system containing 10~20mo1% glass former, P$_2$O$_{5}$ were prepared by melting the batch in pt. crucible followed by quenching on the copper plate. We found that Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$ g1ass-ceramics obtained from crystallization of glass showed significantly higher capacity and longer cycle life than Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$ g1ass. In the present paper, we describe electro-chemical properties during crystallization process and find the best crystallization condition of Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$ g1ass as cathod material. Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$ glass-ceramics shows superior rechargeable capacity of 220 mAh/g in the cycling between 2.0 and 3.9V. between 2.0 and 3.9V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.444-447
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• 2000

The spinel L $i_{1-x}$ M $n_2$ $O_4$has been synthesized by the solid-state reaction. L $i_{l-x}$M $n_2$ $O_4$which includes a mixture of LiOH . $H_2O$ and Mn $O_2$prepared by preliminary heating at 35$0^{\circ}C$ for 12hr. L $i_{l-x}$M $n_2$ $O_4$fired at temperature range from 75$0^{\circ}C$ for 48hr. The structure and the electrochemical characteristics of spinel to L $i_{1-x}$ M $n_2$ $O_4$which is fabricated by changing sintering condition from starting materials are investigated. The cyclic voltammetric measurement was performed using 3 electrode cells. Electrode specific capacity and cycle life behavior were tested in a 3.0~4.2V range at a constant current density of 0.45mA/c $m^2$. To improve the cycle performance of spinel L $i_{l-x}$M $n_2$ $O_4$as the cathode of 4V class lithium secondary batteries, spinel phases L $i_{1-x}$ M $n_2$ $O_4$were Prepared at various lithium. The results showed that discharge capacity of L $i_{l-x}$M $n_2$ $O_4$varied at lithium quantity decrease with increasing lithium add quantity. The discharge capacities of L $i_{0.925}$M $n_2$ $O_4$and LiM $n_2$ $O_4$revealed 108 and 117mAh/g, respectively.spectively.y.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.441-443
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• 2005

According as CCFL(Cold Cathode Fluorescent lamp) of light source in Backlight unit for Note PC (Personal computer) is presently needed to low power consumption and long life time, the development focus of CCFL is going on the discharge gas, phosphor and electrode material. First of all, discharge voltage characteristic of CCFL is closely connected with electrode material For low discharge voltage, the characteristic of electrode material is needed to low work function, low sputtering ratio and superior manufacturing property. We developed new CCFL with Nb/Ni Clad electrode superior to conventional CCFL. Because Nb/Ni Clad electrode with Ni material and Nb material, the electrical characteristic is superior to other electrode materials. The electrode of Nb/Ni Clad is composed that Ni of outside material has superior manufacturing property and Nb of inside material has low work function. Nb/Ni Clad of new electrode material is made by process of Rolling mill at high pressure and heat treatment. We compared electrical characteristic of Nb/Ni clad electrode with conventional Mo electrode by measurement. Mo electrode and Nb/Ni Clad electrode of cup type with diameter 1.1 mm and length 3.0mm are used to this experiment. Material content of Mo electrode is Mo 100%. But, Nb/Ni Clad electrode is composed by content of Nb 40% and Ni 60%. The result of comparison measurement between new CCFL with Nb/Ni Clad electrode and conventional CCFL was appeared that CCFL with Nb/Ni Clad electrode had superior characteristic than conventional CCFL. As a result of experiment, we completed Note PC with low power consumption and long life time by application of new CCFL with Nb/Ni Clad electrode.

• Journal of the Korean Vacuum Society
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• v.14 no.4
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• pp.195-200
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• 2005

For the longevity of OLEDs, passivation of OLEDs is an important process step since organic materials used in OLEDs are very vulnerable to moisture. In this work, the passivation effect of the plasma polymerized para-xylene (PP$\rho$X) layers was studied. The PPpX layers deposited by PECVD were formed on top of the cathode with various plasma powers of 50 - 90 W. Passivation effect of PP$\rho$X was significantly dependent upon the deposition plasma power of the PP$\rho$X film. The lifetime of OLEDs with the 70 W deposited PP$\rho$X passivation layer was about 5 times longer than that of the control device.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.480-480
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• 2010

In the present work, we studied effect of the deposition parameters on the structure and properties of ZnO films deposited by DC arc plasmatron. The varied parameters were gas flow rates, precursor composition, substrate temperature and post-deposition annealing temperature. Vapor of Zinc acetylacetone was used as source materials, oxygen was used as working gas and argon was used as the cathode protective gas and a transport gas for the vapor. The plasmatron power was varied in the range of 700-1,500 watts. Flow rate of the gases and substrate temperature rate were varied in the wide range to optimize the properties of the deposited coatings. After deposition films were annealed in the hydrogen atmosphere in the wide range of temperatures. Structure of coatings was investigated using XRD and SEM. Chemical composition was analyzed using x-ray photo-electron spectroscopy. Sheet conductivity was measured by 4-point probe method. Optical properties of the transparent ZnO-based coatings were studied by the spectroscopy. It was shown that deposition by a DC Arc plasmatron can be used for low-cost production of zinc oxide films with good optical and electrical properties. Sheet resistance of 4 Ohms cm was achieved after the deposition and 30 min annealing in the hydrogen at $350^{\circ}C$. Elevation of the substrate temperature during the deposition process up to $350^{\circ}C$ leads to decreasing of the film's resistance due to rearrangement of the crystalline structure.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.620-624
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• 1992

The analytical performance of glow discharge mass spectrometer (GD-MS), using a flat type ion source is discussed. The efficiency of ion extraction was maximized at the distance between anode and cathode of 6 mm. At the operation condition of 4 mA, -1000 volt, and 1 mbar for the source, the optimum voltages for sampler and skimmer were40 volt and -280 volt, respectively. The intensities of Cu, Zn, and Mn were increased as a function of square root of current approximately. Korea standard reference materials (KSRM) were tested for an application study. The detection limits of most elements were obtained in the range of several ppm at the optimized operating condition. The peaks of aluminum and chromium were interfered by those of residual gases. The depth profile of nickel coated copper specimens (3, 5, 10 ${\mu}m$ thickness) were obtained by plotting time versus intensities of Ni and Cr after checking the thickness of nickel coated using a scanning electron microscope (SEM). At this moment, the sputtering rate of 0.2 ${\mu}m/min$ at the optimum operating condition was determined from the slope of the plot of time to the coating thickness. The roughness spectra of specimen's crater after 16 min, discharge were obtained using a Talysuf5m-120 roughness tester as well.

• Resources Recycling
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• v.30 no.6
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• pp.76-82
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• 2021

The separation of palladium from crude metal, which is obtained from electronic waste using pyrometallurgy was achieved through electrolysis. This was done to recover high-purity copper. The oxidation potentials of these metals are a fundamental part of the analysis of electrolytic separation of palladium and impurity metals. To achieve this, copper, iron, and nickel were dissolved in the electrolyte, and palladium and aluminum were found to be recoverable from anode slime. During the electrolysis for palladium separation, palladium was present in the anode slime and was obtained with a recovery of 97.46 % indicating almost no loss. 4N-grade copper was recovered from the electrodeposition layer at the cathode.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.235-242
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• 2011

This perspective describes recent advances made in the development of various electrochemical technologies to treat waste water containing organic pollutants, reducible/oxidizable and non-reducible/non-oxidizable anions and cations using redox reactions on the solid surface as well as at the interface between solid electrode and liquid electrolyte. Some of representative multiplexing and hybrid electrochemical treatment technologies are discussed, which have great advantages of high efficiency, stability and cost-effective instrumentation without the need of considering non-specific conditions such as high-temperature and high-pressure; however, choices and usages of electrode materials are absolutely critical issues.