• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.93.2-93.2
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• 2011

In this work, graphite nanofibers (GNFs) were prepared for using catalyst supports in fuel cells. The GNFs were chemically activated to obtain high surface area and small pore diameter with different potassium hydroxide (KOH) amounts, i.e., 0, 1, 3, 4, and 5 g as an activating agent. And then Pt-Ru was deposited onto activated GNFs (A-GNFs) by chemical reduction method. The characteristics of Pt-Ru catalysts deposited onto A-GNFs were determined by specific surface area and pore size analyzer, X-ray diffraction (XRD), transmission electron microscopy (TEM), and inductive coupled plasma-mass spectrometer (ICP-MS). The electrochemical properties of Pt-Ru/A-GNFs catalysts were also analyzed by cyclic voltammetry (CV) experiments. From the results, the A-GNFs carbon supports activated with 4 g of KOH (A4g-GNFs) showed that the highest specific surface areas. In addition, the A4g-GNFs led to uniform dispersion of Pt-Ru onto A4g-GNFs, resulting in the enhancement of electrochemical activity of Pt-Ru catalysts.

• Carbon letters
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• v.10 no.3
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• pp.213-216
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• 2009

The electrochemical deposition of Pt nanoparticles on carbon nanotubes (CNTs) supports and their catalytic activities for methanol electro-oxidation were investigated. Pt catalysts of 4~12 nm average crystalline size were grown on supports by potential cycling methods. Electro-plating of 12 min time by potential cycling method was sufficient to obtain small crystalline size 4.5 nm particles, showing a good electrochemical activity. The catalysts' loading contents were enhanced by increasing the deposition time. The crystalline sizes and morphology of the Pt/support catalysts were evaluated using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The electrochemical behaviors of the Pt/support catalysts were investigated according to their characteristic current-potential curves in a methanol solution. In the result, the electrochemical activity increased with increased plating time, reaching the maximum at 12 min, and then decreased. The enhanced electroactivity for catalysts was correlated to the crystalline size and dispersion state of the catalysts.

• Korean Journal of Materials Research
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• v.28 no.3
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• pp.182-188
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• 2018

Nitrogen (N)-doped protein-based carbon as platinum (Pt) catalyst supports from tofu for oxygen reduction reactions are synthesized using a carbonization and reduction method. We successfully prepare 5 wt% Pt@N-doped protein-based carbon, 10 wt% Pt@N-doped protein-based carbon, and 20 wt% Pt@N-doped protein-based carbon. The morphology and structure of the samples are characterized by field emission scanning electron microscopy and transmission electron micro scopy, and crystllinities and chemical bonding are identified using X-ray diffraction and X-ray photoelectron spectroscopy. The oxygen reduction reaction are measured using a linear sweep voltammogram and cyclic voltammetry. Among the samples, 10 wt% Pt@N-doped protein-based carbon exhibits exellent electrochemical performance with a high onset potential of 0.62 V, a high $E_{1/2}$ of 0.55 V, and a low ${\Delta}E_{1/2}=0.32mV$. Specifically, as compared to the commercial Pt/C, the 10 wt% Pt@N-doped protein-based carbon had a similar oxygen reduction reaction perfomance and improved electrochemical stability.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.5
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• pp.424-431
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• 2009

Treatment for water repellency on the carbon supports of GDL which composed a part of MEA has been suggested as a solution to prevent flooding. PTFE is a fluoropolymer that has hydrophobic property and a PTFE emulsion was selected as waterproof agent in this investigation. Carbon paper was coated by PTFE emulsion with different particle size of 5~500 nm and 3~$5\;{\mu}m$ as various concentration. PTFE coated carbon paper has difference in weight variation changed proportionally at PTFE concentration and coating times. Then gas permeability of the coated carbon paper with emulsion of 3~$5\;{\mu}m$ PTFE was changed vastly. Characteristics of carbon paper coated with different PTFE emulsion were analyzed by FE-SEM, FT-IR spcetroscopy and were evaluated by weight variations, gas permeability and water contact angle.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.7
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• pp.1165-1171
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• 2004

The free vibration analyses of the isotropic and CFRP laminated composite rectangular plates with point supports at the fix edge is performed by FEM. We showed optimal position and mode shape of point supports that maximized fundamental natural frequency of the isotropic and CFRP laminated composite rectangular plates by each aspect ratio and the number of point supports.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.531-539
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• 2019

The development of cost-effective electrocatalysts with high durability is one of the most important challenges for the commercialization of polymer electrolyte fuel cells (PEFCs). The durability of the electrocatalyst has been studied in terms of structural change in the active metal and the support. In particular, in fuel cell vehicles, degradation of the carbon-based support is known to have a significant effect on the electrocatalyst deterioration since the start-up/shut-down cycle is frequently repeated. The requirements for the support of the electrocatalyst include high surface area, electrical conductivity, chemical stability, and so on. In this study, we propose the evaluation methods for choosing better support materials and present the physicochemical properties that promising carbon supports should have. Three kinds of carbon materials with different crystallinity are compared. From in-depth study using X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and accelerated stress test, it is clearly confirmed that the durability of carbon-supported electrocatalysts is closely related to the physicochemical properties of the carbon supports.

• Structural Engineering and Mechanics
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• v.88 no.2
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• pp.109-115
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• 2023

In this paper, frequencies of zigzag structure of carbon nanotubes isinvestigated based on Donnell shell theory. These tubes are wrapped with the ring supports in the axial direction. The fundamental frequency curves displayed in article show the dependence of vibrations attributes to zigzag single walled carbon nanotubes. Various zigzag indices are introduced against the variation of length to predict the vibration. Also, the influence of ring supports is sketched with proposed structure for frequency analysis. The frequencies of zigzag tube decreases as the length increases. It is observed that the frequencies decreases with ring support and have higher frequencies without ring. The problem is formulated using Partial Differential Equation. Three expressions of modal deformation displacement functions is used for the elimination of temporal variation to form the solution in the eigen from. For the stability of present study the results are compared with experimentally and numerically in the open text.

• Journal of Powder Materials
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• v.12 no.2 s.49
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• pp.117-121
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• 2005

Platinum catalysts for the DMFC (Direct Methanol Fuel Cell) were impregnated on several carbon supports and their catalytic activities were evaluated with cyclic voltammograms of methanol electro-oxidation. To increase the activities of the Pt/C catalyst, carbon supports with high electric conductivity such as mesoporous carbon, carbon nanofiber, and carbon nanotube were employed. The Pt/e-CNF (etched carbon nanofiber) catalyst showed higher maximum current density of $70 mA cm^{-2}$ and lower on-set voltage of 0.54 V vs. NHE than the Pt/Vulcan XC-72 in methanol oxidation. Although the carbon named by CNT (carbon nanotube) series turned out to have larger BET surface area than the carbon named by CNF (carbon nanofiber) series, the Pt catalysts supported on the CNT series were less active than those on the CNF series due to their lower electric conductivity and lower availability of pores for Pt loading. Considering that the BET surface area and electric conductivity of the e-CNF were similar to those of the Vulcan XC-72, smaller Pt particle size of the Pt/e-CNF catalyst and stronger metal-support interaction were believed to be the main reason for its higher catalytic activity.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.83.2-83.2
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• 2011

In this study, we fabricated tubular ceramic support for segmented-in-series solid oxide fuel cell (SOFC) by using MAO(MgAl-stabilized ) as main material and activated carbon as pore former. Thermal expansion properties of ceramic support with different amounts of activated carbon were analyzed by using dilatometer to decide a suitable sintering temperature. The tubular ceramic supports with different amounts of activated carbon (15, 20, 30wt.%) were fabricated by the extrusion technique. After sintering at $1400^{\circ}C$ for 2h, cross section and surface morphology of tubular ceramic support were analyzed by using SEM image. Also, the porosity, mechanical property, gas permeability of tubular ceramic supports was measured. Based on these results, we established the suitable fabrication technique of tubular ceramic support for segmented-in-series SOFC.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.673-678
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• 2010

In the present study, mixed carbon-supported platinum(Pt) nanoparticles were prepared by a chemical reduction method of Pt precursor solution on two types of carbon materials such as activated carbons(ACs) and graphite nanofibers(GNFs). Average crystalline sizes and loading levels of Pt metal particles could be controlled by changing a content of GNFs. The highest electroactivity for methanol oxidation was obtained by preparing the carbon supports having 15 wt% GNFs. Furthermore, with an increase of GNFs content from 0% to 15%, an electrical conductivity was changed from $10^{-4}S/cm$ to $10^{-1}S/cm$. By an introduction of 10 wt% GNFs additive, the electroactivity of platinum particles was enhanced, but was saturated in the case of 15 wt% GNFs contents. This was related with the fact that the electroactivity change was dependent on the electrical conductivity of mixed carbon supports and Pt particle deposition content or deposition morphology.