• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.6-11
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• 2005

Direct borohydrides fuel cell (DBFC) was emerged to complement the problem of DMFC's low performance and methanol crossover to the cathode and to apply the fuel cell to portable and mobile devices. In this study, the characteristics of novel catalysts was tested to establish the electrode preparation process of DBFC. Pt black and carbon supported-Pt by paste method were used as the cathode catalysts. Pt black, carbon supported-Au and $AB_5$ alloy were used as the anode catalysts. The characteristics of the electrodes were analyzed by XRD, SEM, EDS. The performance test of single cell using the electrodes were carried out in order to evaluate the electrode performance. In the result, the maximum power output was obtained as 366 mW/mg when using Pt/C as anode and cathode catalysts.

• Korean Journal of Materials Research
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• v.18 no.1
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• pp.12-17
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• 2008

Carbon nanotube (CNT) cathodes were fabricated using nano-sized silver (Ag) powders as a bonding material between the CNTs and cathode electrodes. The effects of the powder size on the sintering behavior, the current density and emission image for CNT cathodes were investigated. As the diameter of the Ag powders decreases to 10 nm, the sintering temperature of the CNT cathode was lowered primarily due to the higher specific surface area of the Ag powders. In this study, it was demonstrated that nano-sized Ag powders can be feasibly used as a bonding material for a screen-printed CNT cathode, yielding a high current density and a uniform emission image.

• Journal of the Semiconductor & Display Technology
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• v.17 no.1
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• pp.54-61
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• 2018

In this study, two aspects were analyzed about the robot for removal of explosive devices. First, the cost analyses were performed to provide a reasonable solution for the acquirement of the system. It is processed by an engineering estimate method and the process was consisted of two ways : a system development expense and a mass production unit price. In additions, the resultant cost analyses were compared between the cases excluding and including a mines detection system. As results, in the case of the acquirement of the robot system for removal of explosive devices, it is recommended that the performance by improving the mines detection ability should be considered preferentially rather than the cost because the material cost for the mines detection system is negligible compared to the whole system cost. Second, as a way for improving the system performance by the mine detection function, the carbon nanotube (CNT) based sensor technology was studied in terms of sensitivity and simple productivity with presenting its preliminary experimental results. The detection electrodes were formed by a photolithography method using a photosensitive CNT paste. As results, this method was shown as a scalable and expandable technology for the excellent mines detection sensors.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.723-729
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• 1993

Cu(II) ion-responsive chemically modifed electrodes (CMEs) were constructed by incorporating 1-(2-pyridylazo)-2-naphthol (PAN) into a conventional carbon-paste mixture of graphite powder and Nujol oil. Cu(II) ion was chemically deposited on the surface of the PAN-chemically modified electrode in the absence of an applied potential by immersion of the electrode in a buffer solution (pH 3.2) containing Cu(II) ion, and then reduced at a constant potential in 0.1 M KNO$_3$. And a well-defined voltammetric peak could be obtained by scanning the potential to the positive direction. The electrode surface could be regenerated with exposure to acid solution and reused for the determination of Cu(II) ion. In 5 deposition / measurement / regeneration cycles, the response could be reproduced with 6.1${\%}$ relative standard deviation. In case of using the differential pulse voltammetry, the calibration curve for Cu(II) was linear over the range of 2.0 ${times}$ 10$^{-7}$ ∼ 1.0 ${times}$ 10$^{-6}$ M. And the detection limit was 6.0 ${times}$ 10$^{-8}$ M. Studies of the effect of diverse ions showed that Co, Ni, Zn, Pb, Mg and Ag ions added 10 times more than Cu(II) ion did not influence on the determination of Cu(II) ion, except EDTA and oxalate ions.

• Journal of Biosystems Engineering
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• v.41 no.2
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• pp.75-84
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• 2016

Purpose: In-situ water quality monitoring based on ion-selective electrodes (ISEs) is a promising technique because ISEs can be used directly in the medium to be tested, have a compact size, and are inexpensive. However, signal drift can be a major concern with on-line management systems because continuous immersion of the ISEs in water causes electrode degradation, affecting the stability, repeatability, and selectivity over time. In this study, a computer-based nitrate monitoring system including automatic electrode rinsing and calibration was developed to measure the nitrate concentration in water samples in real-time. Methods: The capabilities of two different types of poly(vinyl chloride) membrane-based ISEs, an electrode with a liquid filling and a carbon paste-based solid state electrode, were used in the monitoring system and evaluated on their sensitivities, selectivities, and durabilities. A feasibility test for the continuous detection of nitrate ions in water using the developed system was conducted using water samples obtained from various water sources. Results: Both prepared ISEs were capable of detecting low concentrations of nitrate in solution, i.e., 0.7 mg/L $NO_3-N$. Furthermore, the electrodes have the same order of selectivity for nitrate: $NO_3{^-}{\gg}HCO_3{^-}$ > $Cl^-$ > $H_2PO_4{^-}$ > $SO{_4}^{2-}$, and maintain their sensitivity by > 40 mV/decade over a period of 90 days. Conclusions: The use of an automated ISE-based nitrate measurement system that includes automatic electrode rinsing and two-point normalization proved to be feasible in measuring $NO_3-N$ in water samples obtained from different water sources. A one-to-one relationship between the levels of $NO_3-N$ measured with the ISEs and standard analytical instruments was obtained.

• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.1-5
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• 2005

Electric double layer capacitors(EDLCS) based on the charge stored at the interface between a hi팀 surface area carbon electrode and an organic electrolyte solution are widely used as a maintenance-free power source for IC memories and microcomputers. The achievement of the excellent performance of the capacitor requires an electrolyte solution which provides high conductivities over a wide temperature range and good electrochemical stabilities to allow the capacitor to be operated at high voltage. The electrochemical capacitor using a carbon material as electrodes and using an organic electrolyte with $1M-LiPF_6$ in PC-GBL-DEC(volume ratio 1:1:2) has specific capacitance of 64F/g.

• Bulletin of the Korean Chemical Society
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• v.11 no.3
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• pp.200-205
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• 1990

Chemically modified electrodes(CMEs), based on 2-imino-1-cyclopentane-dithiocarboxylic acid (icdc) containing carbon paste, have been characterized using cyclic voltammetric techniques. Ag(I) was chemically deposited on the CMEs, and voltammograms were obtained with the electrode in a separate buffer solution. The CME surface can be regenerated with exposure to acid and reused for deposition. In 10 deposition/measurement/regenerate cycles, the linear response have been reproduced up to $1{\times}10^{-6}$ M in linear sweep voltammetry and 1${\times}$10-8 M in differential pulse voltammetry with relative standard deviation of 5.2% and 12.4%, respectiveiy. The sensitivity increased with deposition time and scanning rate, and detection limit was $1{\times}10^{-7}M\;and\;1{\times}10^{-9}M$ at 20 minutes deposition in the linear sweep voltammetry and differential pulse voltammetry, respectively. The presence of some metal ions does not influence the silver ion response. Satisfactory results were obtained for the analysis of the silver ion for a variety of reference materials without interference of Hg ion at the condition of pH = 5-6.

• Analytical Science and Technology
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• v.23 no.2
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• pp.165-171
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• 2010

Glucose oxidase ($GOD_{ox}$) immobilized biosensor was fabricated by two methods. In one of the methods, gold nanoparticles (Au-NPs) prepared by ${\gamma}$-irradiation were loaded into the poly(maleic anhydride)-grafted multi-walled carbon nanotube, PMAn-g-MWCNT electrode via physical entrapment. In the other method, the Au-NPs were prepared by electrochemical reduction of Au ions on the surface of PMAn-g-MWCNT electrode and then GODox was immobilized into the Au-NPs. The $GOD_{ox}$ immobilized biosensors were tested for electrocatalytic activities to sense glucose. The sensing range of the biosensor based on the Au-NPs physically modified PMAn-g-MWCNT electrode was from $30\;{\mu}M$ to $100\;{\mu}M$ for the glucose concentration, and the detection limit was $15\;{\mu}M$. Interferences of ascorbic acid and uric acid were below 7.6%. The physically Au deposited PMAn-g-MWCNT paste electrodes appear to be good sensor in detecting glucose.

• Journal of Electrochemical Science and Technology
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• v.8 no.1
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• pp.43-52
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• 2017

In this paper, for the first time, the electroanalytical study of Triethylenediamine, TEDA was done on a typically graphene modified carbon paste electrode (Gr/CPE) in pH=10.5 of phosphate buffer solutions (PBS). The surface morphology of the bare and modified electrodes was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electro-oxidation of TEDA was investigated at the surface of modified electrode. The results revealed that the oxidation peak current of TEDA at the surface of Gr/CPE is 2.70 times than that shown at bare-CPE. A linear calibration plot was observed in the range of 1.0 to 202.0 ppm. In this way, the detection limit was found to be 0.18 ppm. The method was then successfully applied to determination of TEDA in aqueous samples obtained from two kinds of activated carbon from the masks of war. On the other hand, density functional theory (DFT) method at B3LYP/6-311++G** level of theory and a conductor-like Polarizable Continuum Model (CPCM) was used to calculate the $pK_a$ values of TEDA. The energies of lowest unoccupied molecular orbital ($E_{LUMO}$) and highest occupied molecular orbital ($E_{HOMO}$), gap energy (${\Delta}E$) and some thermodynamic parameters such as Gibbs free energy of TEDA and its conjugate acid ($HT^+$) were calculated. The results of calculated $pK_a$ were found to be in good agreement with the experimental values.

• Analytical Science and Technology
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• v.10 no.3
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• pp.187-195
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• 1997

Chemically modified electrodes(CMEs) for Ag(I) were constructed by incoporating 1,5,9,13-tetrathiacyclohexadecane([16]-ane-$S_4$) with a conventional carbon-paste mixture composed of graphite powder and nujol oil. Ag(I) ion was chemically deposited onto the surface of the modified electrode with [16]-ane-$S_4$ by immersion of the electrode in the acetate buffer solution(pH=4.5) containing $5.0{\times}10^{-4}M$ Ag(I) ion. And then the electrode deposited with Ag(I) was reduced at -0.3V vs. S.C.E. Well-defined stripping voltammetric peaks could be obtained by scanning the potential to the positive direction. The CME surface was regenerated with exposure to 0.1M $HNO_3$ solution and was reused for the determination of Ag(I) ion. When deposition/measurement/regeneration cycles were 10 times, the response could be reproduced with relative standard deviation of 6.08%. In case of differential pulse stripping voltammetry, the calibration curve for Ag(I) was linear over the range of $5.0{\times}10^{-7}{\sim}1.5{\times}10^{-6}M$. And the detection limit was $2.0{\times}10^{-7}M$. Various ions such as Cd(II), Ni(II), Pb(II), Zn(II), Mn(II), Mg(II), EDTA, and oxalate(II) did not influence the determination of Ag(I) ion, except Cu(II) ion.