• Title, Summary, Keyword: Modified electrode

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Mechanically Immobilized Copper Hexacyanoferrate Modified Electrode for Electrocatalysis Amperometric Determination of Glutathione

  • D. Davi Shankaran;S. Sriman Narayanan
    • Bulletin of the Korean Chemical Society
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    • v.22 no.8
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    • pp.816-820
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    • 2001
  • A new copper hexacyanoferrate modified electrode was constructed by mechanical immobilization. The modified electrode was characterised by cyclic voltammetric experiments. Electrocatalytic oxidation of glutathione was effective at the modified electrode at a significantly reduced overpotential and at broader pH range. The modified electrode shows a stable and linear response in the concentration range of 9 ${\times}$10-5 to 9.9 ${\times}$10-4M with a correlation coefficient of 0.9995. The modified electrode exhibits excellent stability, reproducibility and rapid response and can be used in flow injection analysis for the determination of glutathione.

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Amperometric Determination of Nitrite at Poly(Methylene Blue)-Modified Glassy Carbon Electrode

  • Xu, Guang-Ri;Xu, Guifang;Xu, Ming-Lu;Zhang, Zhengqing;Tian, Yuan;Choi, Han-Nim;Lee, Won-Yong
    • Bulletin of the Korean Chemical Society
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    • v.33 no.2
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    • pp.415-419
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    • 2012
  • Electrochemical characteristics of nitrite ion were investigated at a poly(methylene blue)-modified glassy carbon electrode by cyclic voltammetry and differential pulse voltammetry. The poly(methylene blue)-modified glassy carbon electrode exhibited enhanced anodic signals for nitrite. The effects of key parameters on the detection of nitrite were evaluated at the modified electrode, such as pH, accumulation time, and scan rate. Under optimum condition, the chemically modified electrode can detect nitrite in the concentration range $2.0{\times}10^{-6}$ to $5.0{\times}10^{-4}$ M with the detection limit of $2.0{\times}10^{-6}$ M and a correlation coefficient of 0.999. The detection of nitrite using the chemically modified electrode was not affected by common ions such as $Na^+$, $K^+$, $Ca^{2+}$, $Cl^-$, $HPO_4^{2-}$ and $H_2PO_4^- $. The modified electrode showed good stability and reproducibility. The practical application of the present method was successfully applied to the determination of nitrite ion in cabbage samples.

Electrochemistry and Determination of 1-Naphthylacetic Acid Using an Acetylene Black Film Modified Electrode

  • Huang, Wensheng;Qu, Wanyun;Zhu, Dazhai
    • Bulletin of the Korean Chemical Society
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    • v.29 no.7
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    • pp.1323-1325
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    • 2008
  • The acetylene black (AB) was dispersed into water in the presence of dihexadecyl hydrogen phosphate (DHP) via ultrasonication, resulting in a stable and well-distributed AB/DHP suspension. After evaporation of water, an AB/DHP composite film-modified electrode was prepared. The electrochemical responses of $K_3$[Fe$(CN)_6$] at the unmodified electrode, DHP film-modified electrode and AB/DHP film-modified electrode were investigated. It is found that the AB/DHP film-modified electrode possesses larger surface area and electron transfer rate constant. Furthermore, the electrochemical behaviors of 1-naphthylacetic acid (NAA) were examined. At the AB/DHP film-modified electrode, the oxidation peak current of NAA remarkably increases. Based on this, a sensitive and convenient electrochemical method was proposed for the determination of NAA. The linear range is in the range from $4.0 {\times} 10^{-8}\;to\;5.0 {\times} 10^{-6}$ mol $L^{-1}$, and the detection limit is $1.0 {\times} 10^{-8}$ mol $L^{-1}$. Finally, this new sensing method was employed to determine NAA in several soil samples.

Electrochemical Determination of Capsaicin by Ionic Liquid Composite-Modified Electrode

  • Kim, Dong-Hwan;Nam, Sungju;Kim, Jaeyoon;Lee, Won-Yong
    • Journal of Electrochemical Science and Technology
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    • v.10 no.2
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    • pp.177-184
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    • 2019
  • An electrochemical detection method for capsaicin has been developed using ionic liquid (IL) doped graphene-titania-Nafion composite-modified electrode. The combination of IL (1-hexyl-3-methylimidazolium with hexafluorophosphate counter ion) in the composite-modified electrode resulted in a significantly increased electrochemical response for capsaicin compared to that obtained at the corresponding electrode without IL. The increased electrochemical signal could be ascribed to the decreased electron transfer resistance through the composite film and also to the effective accumulation of capsaicin on the electrode surface due to ${\pi}-{\pi}$ interaction of the imidazole groups of IL with the aromatic rings of capsaicin. The present IL composite-modified electrode can detect capsaicin with a concentration range from $3.0{\times}10^{-8}M$ to $1.0{\times}10^{-5}M$ with a detection limit of $3.17{\times}10^{-9}M$ (S/N = 3). The present sensor showed good reproducibility (RSD = 3.2%).

Electro-Catalytic Oxidation of Amoxicillin by Carbon Ceramic Electrode Modified with Copper Iodide

  • Karim-Nezhad, Ghasem;Pashazadeh, Ali;Pashazadeh, Sara
    • Journal of the Korean Chemical Society
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    • v.57 no.3
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    • pp.322-328
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    • 2013
  • Copper iodide was employed as a modifier for preparation of a new carbon ceramic electrode. For the first time, the catalytic oxidation of amoxicillin (AMX) was demonstrated by cyclic voltammetry, chronoamperometry and amperometry methods at the surface of this modified carbon ceramic electrode. The copper iodide modified sol-gel derived carbon ceramic (CIM-SGD-CC) electrode has very high catalytic ability for electrooxidation of amoxicillin. The catalytic oxidation peak current was linearly dependent on the amoxicillin concentration and the linearity range obtained was 100 to 1000 ${\mu}mol\;L^{-1}$ with a detection limit of 0.53 ${\mu}mol\;L^{-1}$. The diffusion coefficient ($D=(1.67{\pm}0.102){\times}10^{-3}\;cm^2\;s^{-1}$), and the kinetic parameter such as the electron transfer coefficient (${\alpha}$) and exchange current density ($j_0$) for the modified electrode were calculated. The advantages of the modified CCE are its good stability and reproducibility of surface renewal by simple polishing, excellent catalytic activity and simplicity of preparation.

Stability Characteristics of Sn Species Behavior on Surface of a Sn-modified Pt Electrode for Electrolytic Reduction of Nitrate Ion (질산염 이온의 전해 환원을 위한 Sn-modified Pt 전극 표면에서의 Sn 안정성 거동 특성)

  • Kim, Kwang-Wook;Kim, Seong-Min;Kim, Yeon-Hwa;Lee, Eil-Hee;Jee, Kwang-Yong
    • Korean Chemical Engineering Research
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    • v.45 no.5
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    • pp.433-441
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    • 2007
  • This work investigated the stability of a Sn-modified Pt electrode, which was used for reduction of nitrate, fabricated by an adsorption or electro-deposition of Sn on Pt. In order to find the causes for instability of the electrode, the effects of the solutions in which the electrode was used and the potential applied to the electrode on the electrochemical and metallurgical behaviors of Sn on Pt were studied. The Sn of freshly- prepared modified-Sn Pt electrode existed as Sn hydroxide form, which brought about an easy loss of the electro-activity of the electrode even staying in water, especially in acid solution. When the Sn-modified Pt electrode was used for the reduction of nitrate, the electro-activity of the electrode was affected depending on the potential applied to the electrode. When a more negative potential than the redox equilibrium potential between $Sn(OH)_2$ and Sn was applied to the electrode, the Sn hydroxide was converted to Sn that could diffused into Pt, which leaded to the loss of electro-activity of the electrode as well. The solid diffusion of Sn increased linearly with the applied potential. The Sn-electrodeposited Pt electrode which had more Sn on the electrode was more favorable to maintaining the integrity of the electrode during the reduction of nitrate than the Sn-adsorbed Pt electrode prepared in the under-potential deposition way.

Evaluation of power density in microbial fuel cells using expanded graphite/carbon nanotube (CNT) composite cathode and CNT anode (팽창흑연·소나노튜브 복합 음극과 탄소나노튜브 양극으로 이루어진 미생물 연료전지의 전력수율 평가)

  • Han, Sun-Kee;Lee, Chae-Young
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.4
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    • pp.503-509
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    • 2013
  • Electrochemical redox capacity of a microbial fuel cell (MFC) electrode is an important factor in the power density. This study was conducted to investigate the redox capacity of surface modified anode and cathode electrodes by measuring their conductivities. An anode electrode was modified with nitric acid and a cathode electrode was modified with heat treatment. The anode electrode modified with 20 % of the nitric acid concentration showed the highest conductivity of $6.2{\mu}S/cm/g$ and the maximum power density of $306.0mW/m^2$ when used in a MFC. The cathode electrode modified at $472^{\circ}C$ for 18 min showed the highest conductivity of $5.2{\mu}S/cm/g$ and the maximum power density of $276.20mW/m^2$ when used in a MFC. On the other hand, an MFC using both the electrodes showed the highest maximum power density of $408.2mW/m^2$. Meanwhile, a control MFC without modified electrodes generated very small voltage (0.014 mV), so the power density could not be measured.

Reciprocal Sustain and Auxiliary Pulse Waveforms Applied to an AC PDP with an Auxiliary Electrode

  • Choi, Kyung-Cheol;Lee, Sung-Min;Choi, Chung-Sock;Jang, Cheol
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1543-1546
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    • 2008
  • Modified pulse waveforms were applied to an AC plasma display panel with an auxiliary electrode in order to improve the operation voltage margin. Reciprocal sustain pulse waveforms and modified auxiliary pulse waveforms were applied to the sustain and auxiliary electrode, respectively. During the sustain period, the influence of the address electrode on the luminous efficacy of long-coplanar gap discharges was mitigated by application of reciprocal sustain pulse waveforms. Modified auxiliary pulse waveforms maintained the high efficacy obtained from the AC PDP with an auxiliary electrode. The proposed reciprocal sustain and modified auxiliary pulses waveforms can induce stable discharges in long-coplanar gap discharges and can control wall charges with a wider auxiliary pulse voltage margin, thereby enhancing the luminous efficacy of the AC PDP with an auxiliary electrode.

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Electro-oxidation of Cyclohexanol on a Copper Electrode Modified by Copper-dimethylglyoxime Complex Formed by Electrochemical Synthesis

  • Hasanzadeh, Mohammad.;Shadjou, Nasrin.;Saghatforoush, Lotfali.;Khalilzadeh, Balal.;Kazeman, Isa.
    • Bulletin of the Korean Chemical Society
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    • v.30 no.12
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    • pp.2943-2948
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    • 2009
  • Copper-dimethylglyoxime complex (CuDMG) modified Copper electrode (Cu/CuDMG) showed a catalytic activity towards cyclohexanol oxidation in NaOH solution. The modified electrode prepared by the dimethylglyoxime anodic deposition on Cu electrode in the solution contained 0.20 M $NH_4Cl\;+\;NH_4OH\;(pH\;9.50)\;and\;1\;{\times}\;10^{-4}$ M dimethylglyoxime. The modified electrode conditioned by potential recycling in a potential range of -900${\sim}$900 mV vs. Ag/AgCl by cyclic voltammetry in alkaline medium (1 M NaOH). The results show that the CuDMG film on the electrode behaves as an efficient catalyst for the electro-oxidation of cyclohexanol in alkaline medium via Cu (III) species formed on the electrode.

Characteristics of Ti Platinization for Fabrication Sn-modified Platinized Ti Electrode (Sn-modified Platinized Ti 전극 제조를 위한 Ti의 백금 도금 특성)

  • Kim, Kwang-Wook;Kim, Seong-Min;Lee, Eil-Hee
    • Korean Chemical Engineering Research
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    • v.45 no.2
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    • pp.124-132
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    • 2007
  • This work investigated a fabrication way of stable platinized Ti electrode and evaluated the electrochemical characteristics of the Sn-modified platinized Ti electrode in nitrate solution. A Pt electro-plating way to form some open special clearances within the Pt coating layer on etched Ti substrate was very important to remove effectively the residual contaminate due to plating solution out of the fabricated electrode surface and to maximize the actual electrode surface area contacting solution. Both boiling and electro-cleaning processes of the fabricated electrode was essential to obtain a stable platinized-Pt electrode with reproducible and stable surface property which was necessary for the correct evaluation of Sn coverage on the electrode. The electro-cleaning caused a morphology change of the platinized Ti electrode surface with some downy hair-like polyps formed during the deposition disappearing, which made the electrode stable. The Sn-modified platinized Ti electrode in this work showed the best electro-activity for nitrate reduction, when it was fabricated through the Pt electro-plating of about 30 minutes.