• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1227-1228
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• 2006

The electrochemical properties of novel metal powders were investigated for the electrode materias of polymer electrolyte memebrane electrolysis. Two types of Pt black and $IrO_2$ powder electrodes were hot-pressed on the polymer electrolyte membrane to form membrane electrode assembly. The galvanodynamic polarization methode was used to characterize the electrochemical properties of both electrodes. From the experimental results, we concluded that the $IrO_2$ powder electrode exhibits better electrochemical performance than Pt black as cathode material for the electrolysis.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.106-112
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• 2021

Catalyst poisoning by ionomers in membrane electrode assemblies of alkaline membrane fuel cells has been reported recently. We tried to improve the membrane electrode assembly's performance by controlling the solvent's ratio during electrode manufacturing. 4 Different mixing ratios of N-Methyl-2-pyrrolidone (NMP) and ethylene glycol (EG) gave four different cathode electrodes with platinum and Fuma-Tech ionomers. The electrode with higher EG improved polarization performance by about 36% compared to the NMP-based commercial ionomer. The dependence of the ionomer's dispersibility on the solvent seems responsible for the difference, which means that the non-uniform distribution of ionomers improves the performance of the electrode. High-frequency resistance, internal resistance corrected polarization curve, Tafel slope, mass activity, and impedance spectroscopy characterized the electrode. We can find that the existence of poor solvent improves cathode electrode performance. It seems to be the result of reduced poisoning of the catalyst according to the particle size distribution of the ionomer.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.65-68
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• 2007

전극 막 접합체를 만드는 방법 중 연속식 공정으로서의 데칼법의 장점은 제조공정의 단순화와 두께 균일성 그리고 대량생산 등을 그 예로 들 수 있다. 본 실험에서는 코터를 이용해 전극 막 접합체를 만들기 위해 높은 점도의 촉매 슬러리를 제조하였다. Johnson Mattey 사의 HiSPEC 40 wt% Pt/C 촉매와 Dupont사의 20 wt% Nafion Solution 그리고 물을 이용하여 촉매 슬러리를 제조한 후 코터를 이용하여 데칼법으로 전극 막 접합체를 제조하였다. 완성된 전극 막 접합체의 성능 평가를 실시하였으며 상용화된 전극 막 접합체와 그 특성을 비교 분석을 실시해보았다.

• New & Renewable Energy
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• v.3 no.1 s.9
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• pp.60-67
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• 2007

Catalyst coated membrane [CCM] type and catalyst coated substrate [CCS] type of membrane electrode assembly [MEA] were manufactured and evaluated their performance. Degradation test were conducted to find the difference of long term stability in two types of MEA and the factor for performance degradation problem occurred. Performance degradation test of single cell in two different types of MEA were carried out when current density was $200mA/cm^{2}$. The degradation test had proceeded for 230 hours and performance degradation was checked by I-V curve and impedance measurement at regular intervals. Also, MEA before/after operation and changes of catalyst layer were characterized by SEM, TEM, and XRD. Maximum power density of CCM type was higher than that of CCS type. Meanwhile, an increase of particle size of catalyst and an increase of impedance resistance after long term operation were observed. In the case of using CCM type MEA, the performance was deteriorated 38% of initial performance. In the case of using CCS type MEA, the performance was deteriorated 43% of initial performance. In consideration of difference of initial performance, performance of CCM type is higher than that of CCS type but both types had similar problems during degradation test.

• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.497-501
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• 2011

Polymer electrolyte membrane fuel cell (PEMFC) performance degrade when sulfur dioxide is present in the fuel hydrogen gas, this is referred as $SO_2$ poisoning. This paper reveals $SO_2$ poisoning on PEMFC cathode part by measuring electrical performance of single cell under 1 ppm and 5 ppm on $SO_2$ gas operating. The security of $SO_2$ poisoning depended on $SO_2$ concentration under the best operating conditions($65^{\circ}C$ of cell temperature and 100% of relative humidity between anode and cathode). $SO_2$ adsorption occured on the surface of catalyst layer on membrane electrode assembly (MEA), In addition, MEA poisoning by $SO_2$ was cumulative but reversible. After poisoning within 5 ppm $SO_2$ for 1hr, the electrical performance of PEMFC was found to recover up to about 93% by cyclic voltametry scan.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.341-348
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• 2016

The experiments related on structure and water electrolysis performance of HALE UAV stack were conducted in this study. Anode catalyst $IrRuO_2$ was prepared by Adam's fusion methods as 2~3 nm nano sized particles, and the cathode catalyst was used as commercial product of Premetek. The MEA (membrane electrode assembly) was manufactured by decal methods, anode and anode catalytic layers were prepared by electro-spray. HALE stack was composed of 5 multi-cells as $0.2Nm^3/hr$ hydrogen production rate with hydrogen pressure as 10 bar. The water electrolysis performance was investigated at atmospheric pressure and temperature of $55^{\circ}C$. Best performance of HALE UAV stack was recorded as cell voltage efficiency as 86%.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.445-449
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• 2012

The activation process of the membrane-electrode assembly (MEA) is important for the mass production of the polymer electrolyte membrane fuel cell. The conventional activation process for the MEA requires excessive time and hydrogen gas and it might become the barrier for the commercialization of the fuel cell. The conventional activation process is based on hydrolysis of ion conducting membrane. In the study, we suggest the cyclic voltammetry (CV) technique as an on-line activation process and the CV activation process consists of two steps : 1) the humidification of the polymer electrolyte membrane and the electrode with 100% RH humidified nitrogen ($N_{2}$) gas, and 2) the removal step of the oxide layer on the surface of the Pt catalyst with CV cycling. The cycling reduces the activation time of the MEA by 2.5 h and use of hydrogen gas by 1/4.

• Korean Chemical Engineering Research
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• v.54 no.4
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• pp.453-458
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• 2016

Microbial fuel cells (MFC) were operated with pig wastes and PEMFC (Proton Exchange Membrane Fuel Cells) MEA (Membrane and Electrode Assembly). Performance of hydrocarbon membrane was compared with that of perfluoro membrane at MFC condition. Sulfonated-Poly(Arylene Ether Sulfone) was used as hydrocarbon membrane and Gore membrane was used as perfluoro membrane. OCV of sPAES MEA was 50mV higher than that of Gore MEA and power density of sPAES MEA was similar that of Gore MEA. Reinforcement of sPAES membrane stabilized the performance of MEA in MFC. The highest performance was obtained at temperature of $45^{\circ}C$ and with culture solution circulation rate of 50 ml/min. The highest power density was $1,100mW/m^2$ at optimum condition in MFC using pig waste.

• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.12-18
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• 2012

The prohibitively high cost of Pt catalyst might be the biggest barrier for the commercialization of proton exchange membrane fuel cells (PEMFC) of which wide application is expected. Worldwide research efforts for the development of alternative to Pt oxygen reduction reaction (ORR) catalyst are made recently. One of the important considerations in the catalyst development is durability issue as well as economic aspect. From this point of view, platinum group metals (PGM) except Pt can be a candidate for replacing Pt catalyst because the material properties and the catalytic activity of PGM are expected to be similar to Pt. In contrast to Ir, Rh and Os to which not so much attention has been paid as an ORR catalyst, Pd that is most similar to Pt in terms of material properties and catalytic activity and Ru that is in the form of chalcogenide have been studied intensively. Activity comparison between non-Pt and Pt oxygen reduction catalysts by half cell test using RDE (rotating disk electrode) or PEMFC MEA (membrane electrode assembly) operation indicates that Pd-based catalysts show the most similar activity to Pt. In this paper we analyze the composition of PGM ORR catalyst in literature to promote the development of non-Pt ORR catalyst.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.22-28
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• 2019

To maximize the oxygen evolution reaction (OER) in the electrolysis of water, nano-grade $IrO_2$ powder with a low specific surface was prepared as a catalyst for a solid polymer electrolyte (SPE) system, and a membrane electrode assembly (MEA) was prepared with a catalyst loading as low as $2mg\;cm^{-2}$ or less. The $IrO_2$ catalyst was composed of heterogeneous particles with particle sizes ranging from 20 to 70 nm, having a specific surface area of $3.8m^2g^{-1}$. The anode catalyst layer of about $5{\mu}m$ thickness was coated on the membrane (Nafion 117) for the MEA by the decal method. Scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) confirmed strong adhesion at the interface between the membrane and the catalyst electrode. Although the loading of the $IrO_2$ catalyst was as low as $1.1-1.7mg\;cm^{-2}$, the SPE cell delivered a voltage of 1.88-1.93 V at a current density of $1A\;cm^{-2}$ and operating temperature of $80^{\circ}C$. That is, it was observed that the over-potential of the cell for the oxygen evolution reaction (OER) decreased with increasing $IrO_2$ catalyst loading. The electrochemical stability of the MEA was investigated in the electrolysis of water at a current density of $1A\;cm^{-2}$ for a short time. A voltage of ~2.0 V was maintained without any remarkable deterioration of the MEA characteristics.