• Composites Research
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• v.33 no.6
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• pp.336-340
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• 2020

In this study, carbon aerogels (CA) were prepared by sol-gel polycondensation of resorcinol and furfural in isopropanol using hexamethylenetetramine as a catalyst, and then directly drying the organic gels under isopropanol freeze-drying conditions, followed by carbonization under a nitrogen atmosphere. The preparation conditions of the CA were explored by changing the mole ratio of resorcinol to furfural. The effect of the preparation conditions on the pore structure of the CA was studied by nitrogen adsorption isotherms. The characteristics of the CA were studied by scanning and transition electron microscopy, and infrared spectrometry. The accessibility of pores and performance of the CA as an electrode in electric double layer capacitors were also electrochemically investigated. As a result, BET surface area and specific capacitance increased with the molar ratio of resorcinol to catalyst (R/C) ratio; the maximum values of 765 ㎡/g and 132 F/g were achieved at the R/C ratio of 200, respectively. Consequently, it was confirmed that increasing the R/C ratio increased the average pore size of the CA electrode, which improved the rate capability of the system.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.154-161
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• 2015

A novel process has successfully been developed by overcoming major difficulties through the elimination of number of process steps involved in the Classical Transesterification reaction during the preparation of Fatty Acid Methyl/Ethyl Ester (FAME.FAEE) called biodiesel. The Classical process with cost intensive process steps such as the utilization of excess alcohol, needing downstream distillation for the recovery and reutilization of excess alcohol/cosolvent, unrecoverable homogenous catalyst which consumes vast quantity of fresh distilled water during the purification of the product and downstream waste water treatment before its safe disposal to the surface water body. The Novel Process FAME/FAEE is produced from any vegetable oil irrespective of edible or inedible variety using sonication energy. The novelty of the finding is the use of only theoretical quantity of alcohol along with a co-solvent and reduced quantity of homogeneous catalyst. Under this condition neither the homogeneous catalyst goes to the FAME layer nor is the distillation needed. The same ester also has been prepared in high pressure high temperature reactor without using catalyst at sub critical temperature. The quality of prepared biodiesel without involving any purification step meets the ASTM standards. Blended Biodiesel with Common Diesel Fuel (CDF) and FAME is prepared, characterized and used as fuel in the Kirloskar make CI Engines. The evaluation of the engine performance result of pure CDF, B05 biodiesel, B10 biodiesel of all types of biodiesel prepared by using the feedstock of Soybean (Glycine max) and Karanja (Pongamia pinnate) oil along with their mixed oil provides useful information such as brake power, brake thermal efficiency, brake specific fuel consumption, etc, and established it as ideal fuel for unmodified CI engine.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.988-993
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• 2002

Electrochemical cells for decomposing $NO_x$ were fabricated using a hydrothermally synthesized lanthanum stannate pyrochlore catalyst. Thick film of the catalyst on the YSZ electrolyte disk was produced by screen-printing a paste consisted of $La_2Sn_2O_7$ and YSZ powders. Direct current was applied to the electrochemical cell to promote an electrochemical catalytic decomposition of $NO_x$. $NO_x$ decomposition behavior of the rectant gas mixture ($NO_x$ 0.1%, $O_2$ 2%) was investigated at 700${\circ}C$ under atmosphere pressure using on-line gas chromatography and $NO_x$ analyzer. It was observed that microstructure of the catalyst layer significantly influences the electrocatalystic decomposition of $NO_x$.

• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.7-12
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• 2002

The gas diffusion electrodes as oxygen cathodes f3r the brine electrolysis process were investigated. The gas diffusion electrode consists of a reaction layer, a gas diffusion layer, and a current distributor. The reaction layer was made from hydrophilic carbon black, hydrophobic carbon black, PTFE(polyterafluoroethylene), and Ag catalyst loaded by the silver mirror reaction or impregnation method. The gas diffusion layer was made from hydrophobic carbon black and PTFE, and Ni mesh was used as the current distributor in the reaction layer. The result that the gas diffusion electrode $(10wt\%\;Ag\;catalyst\;and\;20wt\%\;binder)$ manufactured by applying impregnation method to the carbon black f3r reaction layer showed the better performance was obtained from experiments. From the half-cell test, the measured overpotential of this oxygen cathode was about 700mV, And through the electrolysis experiment under the condition of $80^{\circ}C,\;32wt\%$ NaOH, and $300mA/cm^2$, the electrolysis voltage of this electrode was about 2.2 V, The gas diffusion electrodes manufactured in the present research were capable of continuous operations for three months.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.113-116
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• 2010

We report on the growth and characteristics of the structural and optical properties of InGaN nano-structures doped with antimony (Sb) as a catalyst. The use of catalyst has been explored to modify the growth and defect generation during strained layer heteroepitaxial growth. We performed the growth of the InGaN nano-structures on c-sapphire substrates using mixed-source hydride vapor phase epitaxy (HVPE). The characteristic of samples was measured by scanning electron microscope (SEM) and photoluminescence (PL). The aligning direction of c-axis of the InGaN nano-structures was changed from vertical to parallel or inclined to the surface of substrates when the Sb was added as a catalyst. The indium composition was estimated about 3.2% in both cases of with or without the addition of Sb in the InxGal-xN structures. From the results of InGaN nano-structures formed with the addition of Sb, we can expect the performance of optical devices would be more improved by reduced piezo-electric field if we use the InGaN nano-structures of which c-axes are aligned parallel to the substrates as an active layer.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.527-534
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• 1992

Raney nickel was used as catalyst in the hydrogen electrode for an alkaline fuel cell. The hydrogen electrode manufactured with the Raney nickel catalyst which was sintered at $700^{\circ}C$ was found to have the highest electrode performance. Using the Raney nickel powder of average particle size $90{\AA}$ for the electrode, the current density which had been measured was $450mA/cm^2$ at $80^{\circ}C$ using 6N KOH solution as an electrolyte. The effects of PTFE addition were investigated with CO-chemisorption, polarization curves and Tafel slope. CO-chemisorption had shown the optimum value when the Raney nickel was mixed with 5wt% of PTFE, but from the current density and Tafel slope at porous Raney nickel electrode, the appropriate value of PTFE addition was 10wt%. Recommendable Ni and Al portion for Raney nickel was 60 : 40 and loading amount was $0.25g/cm^2$. Also the influence of pressing pressure for manufacturing catalytic layer and for junction with gas diffusion layer was examined. The morphology of catalyst surface was investigated with SEM. The influence of reactivation time and heat-treatment temperature were also studied.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.374-380
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• 2015

In this paper, a dynamic model describing the 2 phase effect on the gas diffusion layer depending on load change of a fuel cell stack was developed to examine the effects of liquid water in fuel cell cathode gas diffusion layer on the fuel cell performance. For the developed model, 2 phase effect on the performance of a fuel cell stack depending on the load changes, concentration distribution of water vapor and oxygen inside a gas diffusion layer, the effect of the thickness and porosity of the gas diffusion layer on the fuel cell stack voltage were examined. As a result, a fuel cell stack voltage for the 2 phase model within the scope of the research become lower than that for the 1 phase model regardless of the load. Although oxygen molar concentration for the gas diffusion layer adjacent to the catalyst layer was the lowest, water vapor concentration is the highest. In addition, as thickness and porosity of the gas diffusion layer increased and decreased, respectively, the fuel cell stack voltage decreased.

• Macromolecular Research
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• v.14 no.1
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• pp.101-106
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• 2006

The transport of reactant gas, electrons and protons at the three phase interfaces in the catalytic layers of membrane electrode assemblies (MEAs) in proton exchange, membrane fuel cells (PEMFCs) must be optimized to provide efficient transport to and from the electrochemical reactions in the solid polymer electrolyte. The aim of reducing proton transport loss in the catalytic layer by increasing the volume of the conducting medium can be achieved by filling the voids in the layer with small-sized electrolytes, such as dendrimers. Generation 1.5 and 3.5 polyamidoamine (PAMAM) dendrimer electrolytes are well-controlled, nanometer-sized materials with many peripheral ionic exchange, -COOH groups and were used for this purpose in this study. The electrochemically active surface area of the deposited catalyst material was also investigated using cyclic voltammetry, and by analyzing the Pt-H oxidation peak. The performances of the fuel cells with added PAMAM dendrimers were found to be comparable to that of a fuel cell using MEA, although the Pt utilization was reduced by the adsorption of the dendrimers to the catalytic layer.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.133-134
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• 2013

본 연구는 비전도성 소재 상에 무전해 동도금(Electroless Copper)시 수행되는 씨앗층이나 촉매공정 없이 직접 구리 석출물을 얻는 방법 중 하나에 관한 연구이다. 실리콘 웨이퍼상에 확산방지를 위한 Ta 금속확산방지(Metal barrier)막층 형성 후 무전해 동도금에 침지 후 최소한의 전류를 인가한 결과 균일한 구리피막을 얻을 수 있었으며, 표면 및 단면 조직 분석결과 이를 확인할 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.845-848
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• 2003

We investigated a field emission property of CNTs grown on pre-treated substrates by $H_{2}$ plasma etching method in vacuum chamber (<${10^{-7}}$ Torr). To improve the emission characteristics, various catalysts and buffer layers were used. The morphology and density of catalyst layer was controlled by the different plasma pre-treatment conditions, resulting in the control of the growth characteristics of CNTs.