• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.1-5
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• 2021

The PEM(Proton Exchange Membrane)water electrolysis uses the same PEM electrolyte membrane as the PEM fuel cell and proceeds by the same reaction but the opposite direction. The PEM fuel cell has many methods of degradation analysis since many studies have been conducted on the degradation and durability of the membrane and catalyst. We examined whether PEM fuel cell durability evaluation method can be applied to PEM electrolytic durability evaluation. During the PEM electrolytic degradation process, LSV(Linear sweep voltammetry), CV(Cyclic voltammetry), Impedance, SEM(Scanning Electron Microscope) and FT-IR(Fourier Transform Infrared spectroscopy) were analyzed and compared under the same conditions as the PEM fuel cell. As the PEM fuel cell, hydrogen passing through the membrane was oxidized at the Pt/C electrode, and the hydrogen permeation current density was measured to analyze the degree of degradation of the PEM membrane. Electrode degradation could be analyzed by measuring the electrode active area (ECSA) by CV under hydrogen/nitrogen flowing conditions. While supplying hydrogen and air to the Pt/C electrode and the IrO2 electrode, the impedance of each electrode was measured to evaluate the durability of the electrode and membrane.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.2
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• pp.77-82
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• 2022

Recently, research on the development of low-cost/high-efficiency water electrolysis catalysts to replace noble metal catalysts is being actively conducted. Since overvoltage reduces the overall efficiency of the water splitting device, lowering the overvoltage of the oxygen evolution reaction (OER) is the most important task in order to generate hydrogen more efficiently. Currently, noble metal catalysts show excellent characteristics in OER performance, but they are experiencing great difficulties in commercialization due to their high price and efficiency limitations due to low reactivity. In this study, a water electrolysis catalyst Ni-MWCNT was prepared by successfully doping Ni into the MWCNTs structure through the pulsed laser ablation in liquid (PLAL) process. High resolution-transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) were performed for the structure and chemical composition of the synthesized Ni-MWCNT. Catalytic oxygen evolution reaction evaluation was performed by linear sweep voltammetry (LSV) overvoltage characteristics, Tafel slope, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Chronoamperometry (CA) was used for measurement.

• Advances in Energy Research
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• v.7 no.1
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• pp.21-34
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• 2020

Energy storage devices have received a keen interest throughout the world due to high power consumption. A large number of research activities are being conducted on electrochemical double layer capacitors (EDLCs) because of their high power density and higher energy density. In the present study, an EDLC was fabricated using natural graphite based electrodes and ionic liquid (IL) based gel polymer electrolyte (GPE). The IL based GPE was prepared using the IL, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (1E3MITF) with the polymer poly(vinyl chloride) (PVC) and the salt magnesium trifluoromethanesulfonate (Mg(CF₃SO₃)₂ - MgTF). GPE was characterized by electrochemical impedance spectroscopy (EIS), DC polarization test, linear sweep voltammetry (LSV) test and cyclic voltammetry (CV) test. The maximum room temperature conductivity of the sample was 1.64 × 10^-4 Scm^-1. The electrolyte was purely an ionic conductor and the anionic contribution was prominent. Fabricated EDLC was characterized by EIS, CV and galvanostatic charge discharge (GCD) tests. CV test of the EDLC exhibits a single electrode specific capacitance of 1.44 Fg^-1 initially and GCD test gives 0.83 Fg^-1 as initial single electrode specific discharge capacitance. Moreover, a good stability was observed for prolonged cycling and the device can be used for applications with further modifications.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.159-164
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• 2012

Magnesium (Mg) deposition and dissolution behaviors of 0.2 M $MgBu_2-(AlCl_2Et)_2$, 0.5 M $Mg(ClO_4)_2$, and 0.4M $(PhMgCl)_2-AlCl_3$-based electrolytes with and without tris(pentafluorophenyl) borane (TPFPB) are investigated by ex situ scanning electron microscopy (SEM) and galvanostatic cycling of Mg/copper (Cu) cells. To ascertain the factors responsible for the anodic stability of the electrolytes, linear sweep voltammogrametry (LSV) experiments for various electrolytes and solvents are conducted. The effects of TPFPB as an additive on the anodic stability of 0.4M ($(PhMgCl)_2-AlCl_3$/THF electrolyte are also discussed.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.335-340
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• 2016

Hydrogen production through proton exchange membrane water electrolysis (PEMWE) is expeditiously receiving international attention for renewable energy sources as well as energy storage system applications due to its environmentally friendly uses. A series of $Ir_{0.2}Ru_{0.8}O_2$ $Ir_{0.5}Ru_{0.8}O_2$ & $IrO_2$ catalysts were synthesized and electrochemically evaluated by using linear sweep voltammetry (LSV) technique. Furthermore, the PEMWE performances of full cells were evaluated by recording I-V Curves. The developed PEMWE stack was also operated in combination with a proton exchange membrane fuel cell (PEMFC) to demonstrate the discrete regenerative fuel cell (DRFC) performances. Produced hydrogen and oxygen from PEMWE were used as a fuel to operate PEMFC to establish a DRFC system.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.6
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• pp.669-674
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• 2017

In this study, the novel electrochemical and colorimetric analysis methods are suggested to estimate the degree of phosphoric acid ion poisoning on Pt based catalyst surface and to confirm the possibility of replacing the expensive and long time consumed conventional methods. As the ways, the electrochemical half cell tests such as cyclic voltammetry (CV) and linear sweep voltammetry (LSV) are used and the change in chemical behavior by absorption of the phosphoric acid ion on Pt based catalyst surface and hydrogen peroxide decomposition reaction are successfully recognized by colorimetric measurements. Conclusively, it is proved that the new methods show superior sensitivity for identifying the degree of phosphoric acid poisoned on Pt based catalyst.

• Journal of the Korean Electrochemical Society
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• v.3 no.4
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• pp.232-234
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• 2000

Determination of uric acid by electrochemical method using ultrasonic stimulation has been investigated. Effects of sonication power, sonication time, pH of the solution and temperature were studied to obtain the optimal analytical conditions. The stability of the electrode was also examined. The optimal conditions for the sonovoltammetric determination of uric acid were as follows: temperature, $25.0^{\circ}C$ pH 7.0; sonication power, $20W/cm^2$. The calibration curve for the determination of uric acid by sono-LSV was linear over the range of$8.0{\times}10^{-6}\~5.0\times10^{-4}M$ and the limit of detection was $6.5\times10^{-6}M$.

• Journal of Electrochemical Science and Technology
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• v.1 no.1
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• pp.57-62
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• 2010

The lithium ion concentration dependant ionic conductivity and thermal properties of poly(ethylene glycol) methyl ether methacrylate (PEGMA)/acrylonitrile-based copolymer electrolytes with $LiClO_4$ have been studied by differential scanning calorimetry (DSC), linear sweep voltammetry (LSV) and AC complex impedance measurements. In systems with 11 wt% of acrylonitrile all liquid electrolytes were obtained regardless of lithium ion concentration. Complex impedance measurements with stainless steel electrodes give ambient ionic conductivities $8.1\times10^{-6}\sim1.4\times10^{-4}S cm^{-1}$. On the other hand, a hard and soft films at ambient temperature were obtained in copolymer electrolyte system consists of 15 wt% acrylonitrile with 6 : 1 and 3 : 1 of [EO] : [Li] ratio, respectively. DSC measurements indicate the crystalline melting temperature of poly(PEGMA) disappeared completely after addition of $LiClO_4$ in this system due to the complex formation between ethylene oxide (EO) unit and lithium salt. As a result, free standing film with room temperature ionic conductivity of $1.7\times10^{-4}S cm^{-1}$ and high electrochemical stability up to 5.5V was obtained by controlling of acrylonitrile and lithium salt concentration.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.471-477
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• 2016

In this research, the Ir supported $TiO_2$ (P25) catalyst was prepared by precipitation method for oxygen evolution reaction. The $Ir/TiO_2$ catalyst was synthesised by reduction reaction using reducing agent. Physiochemical characterizations of synthesized $Ir/TiO_2$ catalyst was studied by means of SEM, EDS mapping, TEM and XRD. The Electrochemical characterizations were tested by using the technique of CV and LSV by RDE and Potentiostat. Physicochemical properties were characterized with XRD where Iridium metal morphology and Ir(111) and Ir(222) peaks were founded. $Ir0.2Ru0.8O_2$ exhibited higher OER activity than $Ir0.5Ru0.5O_2$ followed by $Ir/TiO_2$ and $IrO_2$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.3
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• pp.143-148
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• 2021

Alkaline oxygen evolution reaction (OER) electrocatalysts have been widely studied for improving the efficiency and green hydrogen production through electrochemical water splitting. Transition metal-based electrocatalysts have emerged as promising materials that can significantly reduce the hydrogen production costs. Among the available electrocatalysts, transition metal-based layered double hydroxides (LDHs) have demonstrated outstanding OER performance owing to the abundant active sites and favorable adsorption-desorption energies for OER intermediates. Currently, cobalt doped nickel LDHs (NiCo LDHs) are regarded as the benchmark electrocatalyst for alkaline OER, primarily owing to the physicochemical synergetic effects between Ni and Co. We report effects of heat-treatment of the as-grown NiCo LDH on electrocatalytic activities in a temperature range from 250 to 400℃. Electrocatalytic OER properties were analysed by linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The heat-treatment temperature was found to play a crucial role in catalytic activity. The optimum heat-treatment temperature was discussed with respect to their OER performance.