• Journal of the Semiconductor & Display Technology
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• v.7 no.4
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• pp.45-49
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• 2008

For the commercialization of polymer electrolyte membrane fuel cell (PEMFC), some serious problems such as the decrease of platinum use as catalysts and a larger overpotential of oxygen reduction reaction (ORR) at cathode must be solved. In this study, 20%Pt/C and 20%PtCo/C catalysts for the cathode of PEMFC were synthesized from the chemical reduction method and evaluated using an electrochemical measurement. The ORR activity of synthesized 20%Pt/C and 20%PtCo/C had higher than that of the 20%Pt/C on the market. The synthesized 20%PtCo/C with the cobalt concentration (Pt:Co atomic ratio) from 5 to 20% showed the highest ORR activity.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.227-232
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• 2000

The LSM-YSZ composite electrode as a mixture of LSM and YSZ shows percolation characteristics. It was identified that the polarization resistance of LSM-YSZ composite electrode depend on YSZ connectivity by changing powder size ratio of the DLSM/DYSZ. That is, YSZ in composite electrode showed low electrochemical activity without YSZ connectivity. However, the polarization resistance decreased abruptly with YSZ connectivity due to high electrochemical activity of YSZ in composite electrode. Because the amount of three phase boundary is dependent on LSM and YSZ particle size, the polarization resistance of cathode decreases as LSM and YSZ particle size decreases.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.499-503
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• 2018

In this paper, cobalt embedded in nitrogen and sulfur co-doped carbon nanotubes (CoNSTs) were synthesized for oxygen reduction reaction (ORR) catalysts. The CoNSTs were prepared through a facile heat treatment method without any templates. Different amounts of the metal salt were employed to examine the physicochemical and electrochemical properties of the CoNSTs. The CoNSTs showed the bamboo-like tube morphology with the encased Co nanoparticles in the tubes. Through the x-ray photoelectron spectroscopy analysis, the catalysts exhibited different chemical states of the nitrogen and sulfur species. As a result, the CoNST performed high activity toward the ORR in an acidic condition with the onset potential of 0.863 V (vs. reversible hydrogen electrode). It was clearly demonstrated from the electrochemical characterizations that the quality of the nitrogen and sulfur species significantly influences the ORR activity rather than the total amount of the dopants.

• 한국전기화학회:학술대회논문집
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• 2005.07a
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• pp.67-70
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• 2005

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.203-206
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• 2002

• 한국전기화학회:학술대회논문집
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• 2001.06a
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• pp.167-170
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• 2001

• 한국전기화학회:학술대회논문집
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• 2004.06a
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• pp.185-190
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• 2004

• Journal of Electrochemical Science and Technology
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• v.2 no.3
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• pp.131-135
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• 2011

It is, in general, believed that during the activation process, the proton conductivity increases due to wetting effect and the electrochemical resistance reduction, resulting in an increase in the fuel cell performance with time. However, until now, very scant information is available on the understanding of activation processes. In this study, dominant variables that effect on the performance increase of membrane electrode assemblies (MEAs) during the activation process were investigated. Wetting, pore restructuring and active metal utilization were analyzed systematically. Unexpectedly, the changes for both ohmic and reaction resistance characterized by the electrochemical impedance spectroscopy (EIS) after initial wetting process were much smaller when considering the degree of cell performance increases. However, the EIS spectra represents that the pore opening of electrode turns into gas transportable structure more easily. The increase in the performance with activation cycles was also investigated in a view of active metals. Though the particle size was grown, the number of effective active sites might be exposed more. The impurity removal and catalytic activity enhancement measured by cyclic voltammetry (CV) could be a strong evident. The results and analysis revealed that, not merely wetting of membrane but also restructuring of electrodeand catalytic activity increase are important factors for the fast and efficient activation of the polymer electrolyte fuel cells.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.606-610
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• 2019

In this study, we demonstrated that the nonenzymatic glucose sensor based on the flexible carbon fiber bundle electrode with BDD nanocomposites (CF-BDD electrode). As a nano seeding method for the deposition of BDD on flexible carbon fiber, electrostatic self-assembly technique was employed. Surface morphology of BDD coated carbon fiber electrode was observed by scanning electron microscopy. And the electrochemical characteristics were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. This CF-BDD electrode exhibited a large surface area, a direct electron transfer between the redox species and the electrode surface and a high catalytic activity, resulting in a wider linear range (3.75~50 mM), a faster response time (within 3 s) and a higher sensitivity (388.8 nA/mM) in comparison to a bare CF electrode. As a durable and flexible electrochemical sensing electrode, this brand new CF-BDD scheme has promising advantages on various electrochemical and wearable sensor applications.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.545-550
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• 2011

We have synthesized a high electrically conductive 4-(2-(4-(acetylthio)phenyl)ethynyl)benzoic acid (APBA) with a conjugated aromatic structure as a bio fix linker, and then fabricated APBA self-assembled monolayer (SAM) with a self-assembly technique. The structure of the prepared APBA SAM was studied and electrochemical properties of APBA SAM immobilized with a ferrocene molecule were investigated. Also, we have examined the molecular orientation and oxidation-reduction redox characteristics of the mixed SAM consisting of APBA and butanethiol (BT) with a X-ray photo electron spectroscopy (XPS) and cyclicvoltammetry, respectively. Electrochemical activity of the mixed SAM was increased with increasing the mixed time. Especially, the maximum redox current was obtained at a mixed time of 36 hrs.