• Title, Summary, Keyword: carbon electrode

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Electrosorption Behavior of $TiO_2$/Activated Carbon Composite for Capacitive Deionization (축전식 이온제거에 대한 $TiO_2$/Activated Carbon 화합물의 전기흡착 거동)

  • Lee, Jeong-Won;Kim, Hong-Il;Kim, Han-Joo;Park, Soo-Gil
    • Applied Chemistry for Engineering
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    • v.21 no.3
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    • pp.265-271
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    • 2010
  • Desalination effects of capacitive deionization (CDI) process was studied using $TiO_2$/activated carbon electrode. In order to enhance the wettability of electrode and decrease a electrode resistance, $TiO_2$ was coated on activated carbon. By means of $TiO_2$ coating on activated carbon, electric double layer to adsorption content in CDI process was increased. It was identified from TEM, XRD, and XPS that the activated carbon based on $TiO_2$ composite was fabricated successfully by means of sol-gel method. As a results of cyclic voltammetry and impedance, it was identified that $TiO_2$/activated carbon electrode has more electric double later capacitance and less diffusion resistance than activated carbon. Also charge-discharge and ion conductivity profiles showed that the ion removal ratios of $TiO_2$/activated carbon electrode in NaCl electrolyte of $1000\;{\mu}S/cm$ more increased about 39% than that of activated carbon. In conclusion it was possible to identify that the carbon electrode coated $TiO_2$ as electrode material was more effective than raw carbon electrode.

Adsorption of Macrocyclic Cobalt Complex on a Glassy Carbon Electrode for the Electrocatalytic Reduction of $O_2$

  • 강찬
    • Bulletin of the Korean Chemical Society
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    • v.19 no.7
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    • pp.754-760
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    • 1998
  • It was found that the adsorption of a cobalt(III) complex with a macrocyclic ligand, C-meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (hmc), was induced on a glassy carbon electrode by heavily oxidizing the electrode surface. Adsorption properties are discussed. The glassy carbon electrode with the adsorbed complex was employed to see the catalytic activities for the electro-reduction of O2. In the presence of oxygen, reduction of (hmc)Co3+ showed two cathodic waves in cyclic voltammetry. Compared to the edge plane graphite electrode at which two cathodic waves were also observed in a previous study, catalytic reduction of O2 occurred in the potential region of the first wave while it happened in the second wave region with the other electrode. A rotating disk electrode after the same treatment was employed to study the mechanism of the O2 reduction and two-electron reduction of O2 was observed. The difference from the previous results was explained by the different reactivity of the (hmc)CoOOH2+ intermediate, which is produced after the two electron reduction of (hmc)Co3+ in the presence of O2.

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MREIT of Postmortem Swine Legs using Carbon-hydrogel Electrodes

  • Minhas, Atul S.;Jeong, Woo-Chul;Kim, Young-Tae;Kim, Hyung-Joong;Lee, Tae-Hwi;Woo, Eung-Je
    • Journal of Biomedical Engineering Research
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    • v.29 no.6
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    • pp.436-442
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    • 2008
  • Magnetic resonance electrical impedance tomography(MREIT) has been suggested to produce cross-sectional conductivity images of an electrically conducting object such as the human body. In most previous studies, recessed electrodes have been used to inject imaging currents into the object. An MRI scanner was used to capture induced magnetic flux density data inside the object and a conductivity image reconstruction algorithm was applied to the data. This paper reports the performance of a thin and flexible carbon-hydrogel electrode that replaces the bulky and rigid recessed electrode in previous studies. The new carbon-hydrogel electrode produces a negligible amount of artifacts in MR and conductivity images and significantly simplifies the experimental procedure. We can fabricate the electrode in different shapes and sizes. Adding a layer of conductive adhesive, we can easily attach the electrode on an irregular surface with an excellent contact. Using a pair of carbon-hydrogel electrodes with a large contact area, we may inject an imaging current with increased amplitude primarily due to a reduced average current density underneath the electrodes. Before we apply the new electrode to a human subject, we evaluated its performance by conducting MREIT imaging experiments of five swine legs. Reconstructed conductivity images of the swine legs show a good contrast among different muscles and bones. We suggest a future study of human experiments using the carbon-hydrogel electrode following the guideline proposed in this paper.

A Study on the Electrical Resistivity of Graphene Added Carbon Black Composite Electrode with Tensile Strain (인장변형에 따른 그래핀복합 카본블랙전극의 저항변화연구)

  • Lee, T.W.;Lee, H.S.;Park, H.H.
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.1
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    • pp.55-61
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    • 2015
  • Stretchable electrode materials are focused to apply to flexible device such as e-skin and wearable computer. Used as a flexible electrode, increase in electrical resistance should be minimalized under physical strain as bend, stretch and twist. Carbon black is one of candidates, for it has many advantages of low cost, simple processing, and especially reduction in resistivity with stretching. However electrical conductivity of carbon black is relatively low to be used for electrodes. Instead graphene is one of the promising electronic materials which have great electrical conductivity and flexibility. So it is expected that graphene added carbon black may be proper to be used for stretchable electrode. In this study, under stretching electrical property of graphene added carbon black composite electrode was investigated. Mechanical stretching induced cracks in electrode which means breakage of conductive path. However stretching induced aligned graphene enhanced connectivity of carbon fillers and maintained conductive network. Above all, electronic structure of carbon electrode was changed to conduct electrons effectively under stretching by adding graphene. In conclusion, an addition of graphene gives potential of carbon black composite as a stretchable electrode.

Study on the Charging Characteristics of a Sealed Type Ni-Cd Cell (밀폐식 Ni-Cd 전지의 충전특성에 관한 연구)

  • Yung Woo Park;Chai Won Kim;Mu Shik Jhon
    • Journal of the Korean Chemical Society
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    • v.15 no.6
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    • pp.347-352
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    • 1971
  • The variations of the positive and negative electrode potentials, and of internal pressure were measured during the charge of the sealed type Ni-Cd cell. Both polarization characteristics of a paste type Cd-electrode as a gas diffusion electrode in 30% KOH solution and the effects of active carbon electrode as an oxygen consuming auxiliary electrode of the Ni-Cd cell on the charging characteristics of the cell were studied. Peak voltage at the end of charge of the cell is ascribed to the peak at the negative electrode potential, which is due to the concentration polarization by the lack of $Cd^{++}$ ion and oxygen concentration. And the recovery of the negative electrode potential is resulted from depolarization by the increasing diffusion limiting current density with the increasing oxygen pressure. The active carbon electrode was effective as an oxygen consuming auxiliary electrode. The internal pressure of the cell could be maintained below 200mmHg even at one hour rate charge and overcharge by the use of active carbon electrode as an auxiliary electrode.

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Electrochemical determination of hydrogen peroxide using carbon paste biosensor bound with butadiene rubber (부타디엔 고무로 결합된 탄소반죽 바이오센서를 이용한 과산화수소의 전기화학적 정량)

  • Yoon, Kil-Joong
    • Analytical Science and Technology
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    • v.23 no.5
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    • pp.505-510
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    • 2010
  • When polybutadiene dissolved in toluene was a binder of carbon powder, the volatility of solvent just after electrode fabrication assured the mechanical solidity of the carbon paste electrode. This characteristic met the qualifications for practical use of carbon paste electrodes. A new enzyme electrode bound with butadiene rubber was constructed. In order to confirm whether it shows quantitative electrochemical behaviors or not, its electrochemical kinetic parameters, e.g. the symmetry factor, the exchange current density, the capacitance of double layer, the time constant, the maximum current, the Michaelis constant and other factors were investigated. These experimental facts showed that butadiene rubber is a recommendable binder for practical use of a carbon paste electrode.

The Determination of Dopamine in the Presence of Ascorbic Acid at the Modified Glassy Carbon Electrode with Phytic Acid and Single-Walled Carbon Nanotubes

  • Bae, Si-Ra;Jeong, Hae-Sang;Jeon, Seung-Won
    • Bulletin of the Korean Chemical Society
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    • v.28 no.12
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    • pp.2363-2368
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    • 2007
  • A glassy carbon electrode (GCE) modified with phytic acid (PA) and single-walled carbon nanotubes (SWNTs) were investigated by voltammetric methods in buffer solution. The PA-SWNTs/GCE-modified electrode demonstrated substantial enhancements in electrochemical sensitivity and selectivity towards dopamine (DA) in the presence of L-ascorbic acid (AA). The PA-SWNTs films promoted the electron transfer reaction of DA, while the PA film, acting as a negatively charged linker, combined with the positively charged DA to induced DA accumulation in the film at pH under 7.4. However, the PA film restrained the electrochemical response of the negatively charged AA due to the electrostatic repulsion. The anodic peak potentials of DA and AA could be separated by electrochemical techniques, and the interferences from AA were effectively eliminated in the DA determination. Linear calibration plots were obtained in the DA concentration range of 0.1-10 μM and the detection limit of the DA oxidation current was determined to be 0.06 μM at a signal-to-noise ratio of 3. The results indicated that the modified electrode is used to determine DA without interference from AA.

A Novel Carbon Nanotube FED Structure and UV-Ozone Treatment

  • Chun, Hyun-Tae;Lee, Dong-Gu
    • Journal of Information Display
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    • v.7 no.1
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    • pp.1-6
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    • 2006
  • A 10" carbon nanotube field emission display device was fabricated with a novel structure with a hopping electron spacer (HES) by screen printing technique. HES plays a role of preventing the broadening of electron beams emitted from carbon nanotubes without electrical discharge during operation. The structure of the novel tetrode is composed of carbon nanotube emitters on a cathode electrode, a gate electrode, an extracting electrode coated on the top side of a HES, and an anode. HES contains funnel-shaped holes of which the inner surfaces are coated with MgO. Electrons extracted through the gate are collected inside the funnel-shaped holes. They hop along the hole surface to the top extracting electrode. In this study the effects of the addition of HES on emission characteristics of field emission display were investigated. An active ozone treatment for the complete removal of residues of organic binders in the emitter devices was applied to the field emission display panel as a post-treatment.

Characteristics of Photoresist-derived Carbon Nanofibers for Li-ion Full Cell Electrode

  • Kim, Hwan-Jun;Joo, Young-Hee;Lee, Sang-Min;Kim, Chang-Il
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.5
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    • pp.265-269
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    • 2014
  • Carbon nanofiber electrode has been fabricated for energy storage systems by the electrospinning of SU-8 precursor and subsequent pyrolysis. Various parameters including the applied voltage, the distance between syringe tip and target collector and the flow rate of the polymer affect the diameter of SU-8 electrospun nanofibers. Shrinkage during pyrolysis decreases the fiber diameter. As the pyrolysis temperature increases, the resistivity decreases dramatically. Low resistivity is one of the important characteristics of the electrodes of an energy storage device. Given the advantages of carbon nanofibers having high external surface area, electrical conductivity, and lithium intercalation ability, SU-8 derived carbon nanofibers were applied to the anode of a full lithium ion cell. In this paper, we studied the physical properties of carbon fiber electrode by scanning transmission microscopy, thermal gravimetric analysis, and four-point probe. The electrochemical characteristics of the electrode were investigated by cyclic voltammogram and electrochemical impedance spectroscopy plots.

Effect of Electrode Design on Electrochemical Performance of Highly Loaded LiCoO2 Positive Electrode in Lithium-ion Batteries (리튬이온 이차전지용 고로딩 LiCoO2 양극의 전극설계에 따른 전기화학적 성능연구)

  • Kim, Haebeen;Ryu, Ji Heon
    • Journal of the Korean Electrochemical Society
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    • v.23 no.2
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    • pp.47-55
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    • 2020
  • Highly loaded LiCoO2 positive electrodes are prepared to construct high-energy density lithium-ion batteries, their electrochemical performances are evaluated. For the standard electrode, a loading of about 2.2 mAh/㎠ is used, and for a high-loading electrode, an electrode is manufactured with a loading level of about 4.4 mAh/㎠. The content of carbon black as electronic conducting additive, and the porosity of the electrode are configured differently to compare the effects of electron conduction and ionic conduction in the highly loaded LiCoO2 electrode. It is expected that the electrochemical performance is improved as the amount of the carbon black increases, but the specific capacity of the LiCoO2 electrode containing 7.5 weight% carbon black is rather reduced. When the conductive material is excessively provided, an increase of electrode thickness by the low content of the LiCoO2 active material in the same loading level of the electrode is predicted as a cause of polarization growth. When the electrode porosity increases, the path of ionic transport can be extended, but the electron conduction within the electrode is disadvantageous because the contact between the active material and the carbon black particles decreases. As the electrode porosity is lowered through the sufficient calendaring of the electrode, the electrochemical performance is improved because of the better contact between particles in the electrode and the reduced electrode thickness. In the electrode design for the high-loading, it is very important to construct the path of electron conduction as well as the ion transfer and to reduce the electrode thickness.