• Journal of Electrochemical Science and Technology
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• 제11권1호
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• pp.84-91
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• 2020

The PtBi/C and PtBiPd/C electrocatalysts were synthesized via the irreversible adsorption of Pd and Bi ions precursors on commercial Pt/C catalysts. XRD and XPS revealed the formation of an alloy structure among Pt, Bi, and Pd atoms. The current of direct formic acid oxidation (I_d) increased ~ 8 and 16 times for the PtBi/C and PtBiPd/C catalysts, respectively, than that of commercial Pt/C because of the electronic, geometric, and third body effects. In addition, the increased ratio between the current of direct formic acid oxidation (I_d) and the current of indirect formic acid oxidation (I_ind) for the PtBi/C and PtBiPd/C catalysts suggest that the dehydrogenation pathway is dominant with less CO formation on these catalysts.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2685-2690
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• 2013

The activities of Au-modified Cu electrodes toward glucose oxidation are evaluated according to their fabrication conditions and physico-chemical properties. The Au-modified Cu electrodes are fabricated by the galvanic displacement of Au on a Cu substrate and the characteristics of the Au particles are controlled by adjusting the displacement time. From the glucose oxidation tests, it is found that the Au modified Cu has superior activity to the pure Au or Cu film, which is evidenced by the negative shift in the oxidation potential and enhanced current density during the electrochemical oxidation. Though the activity of the Au nanoparticles is a contributing factor, the enhanced activity of the Au-modified Cu electrode is due to the increased oxidation number of Cu through the electron transfer from Cu to more electronegative Au. The depletion of electron in Cu facilitates the oxidation of glucose. The stability of the Au-modified Cu electrode was also studied by chronoamperometry.

• 한국생산제조학회지
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• 제21권4호
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• pp.575-581
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• 2012

The electrochemical oxygen demand (ECOD) is an additional sum parameter, which has not yet found the attention it deserves. It is defined as the oxygen equivalent of the charge consumed during an electrochemical oxidation of the solution. Only one company has yet developed an instrument to determine the ECOD. This instrument uses $PbO_2$-electrodes for the oxidation and has been successfully implemented in an automatic on-line monitor. A general problem of the ECOD determination is the high overpotential of electrochemical oxidations of most organic compounds at conventional electrodes. Here we present a new approach for the ECOD determination, which is based on the use of a solid composite electrodes with highly efficient electro-catalysts for the oxidation of a broad spectrum of different organic compounds. Lead dioxide as an anode material has found commercial application in processes such as the manufacture of sodium per chlorate and chromium regeneration where adsorbed hydroxyl radicals from the electro-oxidation of water are believed to serve as the oxidizing agent. The ECOD sensors based on the Au/$PbO_2$ electrode were operated at an optimized applied potential, +1.6 V vs. Ag/AgCl/sat. KCl, in 0.01 M $Na_2SO_4$ solution, and reduced the effect of interference ($Cl^-$ and $Fe^{2-}$) and an expended lifetime (more than 6 months). The ECOD sensors were installed in on-line auto-analyzers, and used to analyze real samples.

• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.80-85
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• 2005

Electrochemical control of the metabolic flux of W. kimchii sk10 on glucose and pyruvate was studied. The growing cell of W. kimchii sk10 produced 87.4 mM lactate, 69.3 mM ethanol, and 4.9mM lactate from 83.1mM glucose under oxidation condition of the anode compartment, but 98.9 mM lactate, 84.3mM ethanol, and 0.2 mM acetate were produced from 90.8 mM glucose under reduction condition of the cathode compartment for 24 h, respectively. The resting cell of W. kimchii sk10 produced 15.9 mM lactate and 15.2 mM acetate from 32.1 mM pyruvate under oxidation condition of the anode compartment, and 71.3 mM lactate and 3.8 mM acetate from 79.8mM pyruvate under reduction condition of the cathode compartment. The redox balance (NADH/$NAD^+$) of metabolites electrochemically produced from pyruvate was 1.05 and 18.76 under oxidation and reduction conditions, respectively. On the basis of these results, we suggest that the neutral red (NR) immobilized in bacterial membrane can function as an electron channel for the electron transfer between electrode and cytoplasm without dissipation of membrane potential, and that the bacterial fermentation of W. kimchii sk10 can be shifted to oxidized or reduced pathways by the electrochemical oxidation or reduction, respectively.

• 공업화학
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• 제33권4호
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• pp.436-439
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• 2022

벤질알코올의 전기화학적 산화를 통해 𝛽-hydroxynitrile과 𝛽-ketonitrile을 합성하였다. 이 생성물은 용매인 아세토나이트릴이 전기화학적으로 환원되어 생성된 아세토나이트릴 음이온과 벤질알코올이 산화된 벤즈알데하이드의 첨가반응을 통해 생성되었을 것이라고 예상된다. 그리고 20 mA의 전류를 3 h 인가하였을 때, cyanomethylation를 통해 생성된 𝛽-hydroxynitrile이 전기화학적으로 산화되어 최종적으로 𝛽-ketonitrile이 합성됨을 확인하였다. 본 연구에서는 상온에서 가장 범용적으로 사용되는 백금 전극을 이용하여 벤질알코올을 전기화학적으로 𝛽-hydroxynitrile 또는 𝛽-ketonitrile로 합성하는 것이 가능한 것을 입증하였다.

• 전기화학회지
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• 제16권2호
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• pp.70-73
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• 2013

산화 이리듐은 물의 산화반응에 대해 좋은 전기촉매 물질로서 많은 연구가 이루어 지고 있다. 최근 전기화학적 증폭방법을 이용하여 산화 이리듐 나노입자의 개별적인 촉매특성을 연구한 결과를 보면 촉매반응에 의한 전류가 지속적으로 유지되지 않고 시간에 따라 감소하는 결과가 얻어 졌다. 이러한 촉매특성의 사라짐에 대한 원인을 규명하고자 사이즈가 큰 이리듐전극을 산화시킨 산화이리듐 전극에서 물의 산화반응을 진행시켰다. 그 결과 나노입자에서와 유사하게 전류가 감소하는 현상이 관찰되었다. 큰 전극에서의 실험에서는 발생하는 산소방울을 관찰 할 수 있었는데 산소방울의 발생 주기가 전류의 증감주기와 일치하는 것으로 보아 전류의 감소는 산소방울에 의한 버블 과전압 때문으로 생각된다.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.91-96
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• 2016

Oxidation behaviours of ash free coal (AFC), carbon, and H₂ fuels were investigated with a coin type molten carbonate fuel cell. Because AFC has no electrical conductivity, its oxidation occurs via gasification to H₂ and CO. An interesting behaviour of mass transfer resistance reduction at higher current density was observed. Since the anode reaction has the positive reaction order of H₂, CO₂ and H₂O, the lack of CO₂ and H₂O from AFC results in a significant mass transfer resistance. However, the anode products of CO₂ and H₂O at higher current densities raise their partial pressure and mitigate the resistance. The addition of CO₂ to AFC reduced the resistance sufficiently, thus the resistance reduction at higher current densities did not appear. Electrochemical impedance results also indicate that the addition of CO₂ reduces mass transfer resistance. Carbon and H₂ fuels without CO₂ and H₂O also show similar behaviour to AFC: mass transfer resistance is diminished by raising current density and adding CO₂.

• 한국표면공학회지
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• 제49권2호
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• pp.119-124
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• 2016

Plasma electrolytic oxidation (PEO) is a promising coating process to produce ceramic oxide on valve metals such as Al, Mg and Ti. The PEO coating is carried out with a dilute alkaline electrolyte solution using a similar technique to conventional anodizing. The coating process involves multiple process parameters which can influence the surface properties of the resultant coating, including power mode, electrolyte solution, substrate, and process time. In this study, ceramic oxide coatings were prepared on commercial Al alloy in electrolytes with different KOH concentrations (0.5 ~ 4 g/L) by plasma electrolytic oxidation. Microstructural and electrochemical characterization were conducted to investigate the effects of electrolyte concentration on the microstructure and electrochemical characteristics of PEO coating. It was revealed that KOH concentration exert a great influence not only on voltage-time responses during PEO process but also on surface morphology of the coating. In the voltage-time response, the dielectric breakdown voltage tended to decrease with increasing KOH concentration, possibly due to difference in solution conductivity. The surface morphology was pancake-like with lower KOH concentration, while a mixed form of reticulate and pancake structures was observed for higher KOH concentration. The KOH concentration was found to have little effect on the electrochemical characteristics of coating, although PEO treatment improved the corrosion resistance of the substrate material significantly.

• Journal of Electrochemical Science and Technology
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• 제7권3호
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• pp.206-213
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• 2016

Transition metal oxide-based electrodes for lithium ion batteries have recently attracted much attention because of their high theoretical capacity. Here we report the electrochemical behavior of cobalt oxide nanorods as anodes, prepared by a template-free, one-step electrochemical deposition of cobalt nanorods, followed by an oxidation process. The as-deposited cobalt has a slightly convex columnar structure, and controlled thermal oxidation produces cobalt oxides of different Co/O ratios, while the original shape is largely preserved. As an anode in a rechargeable lithium battery, the Co/O ratio has a strong effect on initial capacity and cycling stability. In particular, the one-dimensional Co@Co_xO_y core shell structure obtained from a mild heat-treatment results in superior cycling stability.

• Bulletin of the Korean Chemical Society
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• 제26권10호
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• pp.1560-1564
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• 2005

The influence of cetyltrimethylammonium bromide (CTAB) on the electrochemical behavior of bisphenol A at the carbon paste electrode (CPE) was investigated. CTAB, with a hydrophobic C-H chain, can adsorb at the CPE surface via hydrophobic interaction and then change the electrode/solution interface, and finally affects the electrochemical response of bisphenol A, confirming from the remarkable oxidation peak current enhancement. The electrode process of bisphenol A was examined, and then all the experimental parameters which affects the electrochemical response of bisphenol A, such as pH value of the supporting electrolyte, accumulation potential and time, potential scan rate and the concentration of CTAB, were examined. Finally, a sensitive and simple voltammetric method was developed for the determination of bisphenol A. Under the optimum conditions, the oxidation peak current of bisphenol A varied linearly with its concentration over the range from $2.5\;{\times}\;10^{-8}\;to\;1\;{\times}\;10^{-6}$ mol/L, and the detection limit was found to be $7.5\;{\times}\;10^{-9}$ mol/L. This method was successfully employed to determine bisphenol A in some waste plastic samples.