• 전기화학회지
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• 제13권1호
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• pp.50-56
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• 2010

Multi-wall carbon nano-tube(MWCNT)를 이용해 screen printed carbon electrodes(SPCEs)을 제작하여 혈당센서의 선택성과 감도가 증가됨을 확인 할 수 있었다. 효소촉매반응을 위한 탄소전극으로의 전자이동의 매개체로 8족 금속 원소인 오스뮴을 중심금속으로 일차 아민을 포함하는 피리딘(pyridine) 리간드를 배위시켜 $[Os(dme-bpy)_2(4-aPy)Cl]^{+/2+}$를 합성하였다. 합성된 오스뮴 착물은 순환 전압전류법을 포함한 다양한 전기화학분석방법을 이용하여 전기적 성질을 조사하였다. 전기적 흡착방법을 이용하여 일차 아민을 갖는 착화합물을 전극위에 고정화 하였다. 오스뮴이 고정화된 MWCNT-SPCEs는 일반적인 carbon electrode보다 약 100배가량의 오스뮴이 흡착됨을 확인 할 수 있었다. (${\tau}_0=2.0\;{\times}\;10^{-9}\;mole/cm^2$) 마지막으로 당(Glucose)과 당 분해효소(Glucose Oxidase, GOx)에 의한 촉매반응의 전류를 확인하였고, 당 농도에 따라 선형 변화하는 전류의 양도 확인하였다.

• Journal of Electrochemical Science and Technology
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• 제10권4호
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• pp.416-423
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• 2019

A novel non-enzymatic oxalic acid (OA) sensor based on the platinum/carbon black-nickel-reduced graphene oxide (Pt/CBNi-rGO) nanocomposite is reported. The nanocomposites were prepared by the ethylene glycol reduction method. Their morphology and chemical composition were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The results clearly demonstrated the formation of the Pt/CB-Ni-rGO nanocomposite. The electrocatalytic activity of the Pt/CB-Ni-rGO electrode was investigated by cyclic voltammetry. It was determined that the appropriate amount of Pt enhanced the catalytic activity of Pt for oxalic acid electro-oxidation. Moreover, the modified electrode was determined to be highly selective for oxalic acid without interference from compounds commonly found in urine including uric acid and ascorbic acid. The chronoamperometric signal gave a wide linearity range of 20 μM-60 mM and the detection limit (3σ) was found to be 2.35 μM. The proposed method showed high selectivity, stability, and good reproducibility and could be used with micro-volumes of sample for the detection of oxalic acid. Finally, the oxalic acid content in artificial and control urine samples were successfully determined by our proposed electrode.

• Journal of Electrochemical Science and Technology
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• 제10권4호
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• pp.361-372
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• 2019

The silver nanoparticles/polyaniline/reduced graphene oxide nanocomposite modified glassy carbon electrode (Ag/PANI/RGO/GCE) was prepared by the electrochemical method. The Ag/PANI/RGO nanocomposite was characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, X-ray diffraction (XRD), and electrochemical impedance spectroscopy (ESI). Two electrochemical techniques namely differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were used to the electrochemical behaviors investigation of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The Ag/PANI/RGO/GCE exhibited remarkable electrocatalytic activity towards the oxidation reaction of AA, DA, and UA in Britton-Robinson (BR) solution (pH=4.0). Under the optimal conditions, the determinations of AA, DA, and UA were accomplished using DPV. AA-DA and DA-UA peak potential separations were 130 and 180 mV, respectively. For simultaneous detection, the linear response ranges were in the two concentration ranges of 0.05-0.8 mM and 2.0-16.0 mM with detection limit 0.412 μM (S/N = 3) for AA, 0.7-90.0 μM and 90.0-1000.0 μM with detection limit 0.023 μM (S/N = 3) for DA, and 0.8-70.0 μM and 70.0-1000.0 μM with detection limit 0.050 μM (S/N = 3) for UA. This modified electrode showed good sensitivity, selectivity, and stability with applied to determine AA, DA, and UA in human urine and drug.

• 한국재료학회지
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• 제21권3호
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• pp.138-143
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• 2011

Nanosized Pt, Pt-Ru and Pt-$CeO_2$ electrocatalysts supported on acid-treated carbon nanotube (CNT) were synthesized by microwave-assisted heating of polyol process using $H_2Cl_6Pt{\cdot}6H_2O$, $RuCl_3$, $CeCl_3$ precursors, respectively, and were characterized by XRD and TEM. And then the electrochemical activity of methanol oxidation for catalyst/CNT nanocomposite electrodes was investigated. The microwave assisted polyol process produced the nano-sized crystalline catalysts particles on CNT. The size of Pt supported on CNT was 7~12 nm but it decreased to 3~5 nm in which 10wt% sodium acetate was added as a stabilizer during the polyol process. This fine Pt catalyst particles resulted in a higher current density for Pt/CNT electrode. It was also found that 10 nm size of PtRu alloys were formed by polyol process and the onset potential decreased with Ru addition. Cyclic voltammetry analysis revealed that the $Pt_{75}Ru_{25}/CNT$ electrode had the highest electrochemical activity owing to a higher ratio of the forward to reverse anodic peak current. And the chronoamperemetry test showed that $Pt_{75}Ru_{25}$ catalyst had a good catalyst stability. The activity of Pt was also found to be improved with the addition of $CeO_2$.

• 한국전기전자재료학회논문지
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• 제27권9호
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• pp.582-588
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• 2014

3 mol% Co-added $Ni(OH)_2$ fine powders, which showed ${\beta}$-phase, as positive electrode materials have been fabricated using $NiSO_4{\cdot}6H_2O$ aqueous solution by ultrasonic spray-chemical precipitation and subsequent hydrothermal method, and sheet-like Ni nanopowder was fabricated by mechano-chemical reduction method. The addition effects of the sheet-like Ni nanopowder on the electrochemical properties of the positive electrode in Ni-Zn Redox flow battery were investigated. Impedance spectroscopy revealed that the addition of the sheet-like Ni nanopowder resulted in decrease in the electrical resistivity; 10 wt.% addition reduced the electrical properties by a fifth. Cyclic voltammetry showed the addition of the sheet-like Ni nanopowder resulted in decrease in the potential difference of oxidation and reduction; this means the increase in the reversability for electrode reduction. Charge/discharge measurement confirmed that the addition of the sheet-like Ni nanopowder resulted in the increase in the discharge efficiency.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1120-1128
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• 2004

The SCBFC was composed of bilayered cathode, the outside of which was modified with $Fe^{3+}$ (graphite-Fe(III) cathode) and the inside of which was porcelain membrane, and of an anode which was modified with $Mn^{4+}$ (graphite­Mn(lV) anode). The graphite-Fe(III), graphite-Mn(IV), and porcelain membrane were designed to have micropores. The outside of the cathode was exposed to the atmosphere and the inside was contacted with porcelain membrane. In all SCBFCS the graphite-Fe(III) was used as a cathode, and graphite-Mn(IV) and normal graphite were used as anodes, for comparison of the function between normal graphite and graphite-Mn(IV) anode. The potential difference between graphite-Mn(IV) anode and graphite-Fe(III) cathode was about 0.3 volt, which is the source for the electron driving force from anode to cathode. In chemical fuel cells composed of the graphite-Mn(IV) anode and graphite-Fe(III) cathode, a current of maximal 13 mA was produced coupled to oxidation of NADH to $NAD^{+}$ the current was not produced in SCBFC with normal graphite anode. When growing and resting cells of E. coli were applied to the SCBFC with graphite-Mn(IV) anode, the electricity production and substrate consumption were 6 to 7 times higher than in the SCBFC with normal graphite anode, and when we applied anaerobic sewage sludge to SCBFC with graphite-Mn(IV) anode, the electricity production and substrate consumption were 3 to 5 times higher than in the SCBFC with normal graphite anode. These results suggest that useful electric energy might possibly be produced from SCBFC without electron mediators, electrode-active bacteria, and extra energy consumption for the aeration of catholyte, but with wastewater as a fuel.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3695-3702
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• 2013

A nickel(II) complex $[Ni(H_2biim)_2(H_2O)_2](ClO_4)_2{\cdot}H_2O$ (1) of biimidazole ligand has been synthesized and characterized (Where $H_2biim$ = 2,2'-biimidazole). The single crystal X-ray diffraction of the complex shows a dimeric structure with six coordinated psudo-octahedral geometry. The cyclic voltammograms of complex exhibited one quasireversible reduction wave ($E_{pc}=-0.61V$) and an irreversible oxidation wave ($E_{pa}=1.28V$) in DMF solution. The interaction of the complex with Calf-Thymus DNA (CT-DNA) has been investigated by absorption and fluorescence spectroscopy. The complex is an avid DNA binder with a binding constant value of $1.03{\times}10^5M^{-1}$. The results suggest that the nickel(II) complex bind to CT-DNA via intercalative mode and can quench the fluorescence intensity of EB bind to CT-DNA with $K_{app}$ value of $3.2{\times}10^5M^{-1}$. The complex also shown efficient oxidative cleavage of supercoiled pBR322 DNA in the presence of hydrogen peroxide as oxidizing agent. The DNA cleavage by complex in presence of quenchers; viz. DMSO, KI, $NaN_3$ and EDTA reveals that hydroxyl radical or singlet oxygen mechanism is involved. The complex showed invitro antimicrobial activity against four bacteria and two fungi. The antimicrobial activity was nearer to that of standard drugs and greater than that of the free ligand.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2771-2775
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• 2011

Poly-ethylenedioxypyrrole (PEDOP) coated thiolated multiwall carbon nanotubes palladium nanoparticles (MWCNTs-Pd) modified glassy carbon electrode (GCE) [PEDOP/MWCNTs-Pd/GCE] for the determination of hydroquinone (HQ) and it’s isomer catechol (CA) were synthesized and compared with bare GCE and thiolated multiwall carbon nanotubes (MWCNTs-SH/GCE). The modification could be made by simple processes on a GCE with MWCNTs-Pd covered by PEDOP in a 0.05 M tetrabutylammonium perchlorate (TBAP)/MeCN solution system. A well-defined peak potential evaluation of the oxidation of hydroquinone to quinone at 0.05 V (vs. Ag/AgCl), and electrochemical reduction back to hydroquinone were found by cyclic voltammetry (CV) in phosphate buffered saline (PBS) at pH 7.4. Peak current values increased linearly with increasing hydroquinone contents. The peak separation between the anodic and cathodic peaks at the PEDOP/MWCNTs-Pd/GCE was ${\Delta}Ep$ = 40 mV for HQ and ${\Delta}Ep$ = 70 mV for CA, resulting in a higher electron transfer rate. Moreover, good reproducibility, excellent storage stability, a wide linear range (0.1 ${\mu}M$ - 5 mM for HQ and 0.01 ${\mu}M$ - 6 mM for CA), and low detection limits ($2.9{\times}10^{-8}$ M for HQ and $2.6{\times}10^{-8}$ M for CA; S/N = 3) were determined using differential pulse voltammetry (DPV) and amperometric responses; this makes it a promising candidate as a sensor for determination of HQ and CA.

• 전기화학회지
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• 제10권2호
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• pp.150-154
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• 2007

본 연구에서는 8족 금속 원소인 오스뮴을 중심금속으로 일차아민을 포함하고 있는 피리딘 (pyridine) 화합물을 배위시켜 착화합물을 합성하였다. 합성된 오스뮴 착화합물은 $[Os(dme-bpy)_2(ap-im)Cl]^{+/2+}$을 순환전압전류법을 포함한 다양한 전기화학분석법을 이용하여 전기적인 성질을 조사하였다. 또한 합성된 일차 아민을 갖는 오스뮴 착화합물을 이용하여 당 측정용 바이오센서를 제작하기 위하여 금 나노입자(Cold nano-particles)를 전기적 흡착방법을 이용하여 스크린 인쇄방법으로 만든 탄소반죽 전극 (Screen Printed Carbon Electrodes, SPEs) 위에 고정화를 시켰다. 당과 당 분해효소(Glucose Oxidase, GOx)를 혼합하여 발생하는 산화촉매전류를 확인하였고, 당 농도에 따라 변화하는 산화촉매전류의 양도 확인하였다. 새롭게 만들어진 바이오센서는 1 mM 과 같은 낮은 농도에서 감응할 수 있는 바이오센서에 응용할 수 있음을 확인하였다.

• 전기화학회지
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• 제12권1호
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• pp.54-60
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• 2009

The redox characteristics of 2-arylaldehydehydrazono-3-phenyl-5-substituted-2, 3-dihydro-1, 3, 4-thiadiazoles (1a-h) have been investigated in nonaqueous solvents such as 1, 2-dichloroethane (DCE), dichloromethane (DCM), acetonitrile (AN), Tetrahydrofuran (THF), and dimethylsulfoxide (DMSO) at platinum electrode. Through controlled potential electrolysis, the oxidation and reduction products of the investigated compounds had been separated and indentified. The redox mechanism had been suggested and proved. It had been found that all the investigated compounds were oxidized in two irreversible one-electron processes following the well-known pattern of The EC-mechanism; the first electron loss gives the corresponding cation-radical which is followed by proton removal from the ortho-position in the N-phenyl ring forming the radical. The obtained radical undergoes a second electron uptake from the nitrogen in the N = C group forming the unstable intermediate (di-radical cation) which undergoes ring closure forming the corresponding cation. The formed cation was stabilized in solution through its combination with a perchlorate anion from the medium. On the other hand, these compounds are reduced in a single two-electron process or in a successive two one-electron processes following the well known pattern of the EEC-mechanism according to the nature of the substituent; the first one gives the anion-radical followed by a second electron reduction to give the dianion which is basic enough to abstract protons from the media to saturate the (C = O) bond.