• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2423-2430
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• 2014

Nitrogen-doped short tubular carbons (N-STCs) with big inner diameter have been successfully synthesized via carbonization of polydopamine (PDA) wrapped halloysite nanotubes (HNTs). The obtained N-STCs have average length of $0.3{\mu}m$ with big inner diameter (50 nm), thin wall (2-3 nm) and large surface area ($776m^2g^{-1}$), and show excellent electrochemical properties. As an example in electrochemical applications, N-STCs were used to electrochemically detect hydrogen peroxide ($H_2O_2$) and glucose. The results showed that the N-STCs modified glassy carbon (N-STCs/GC) electrode had much better analytical performance (lower detection limit and wider linear range) compared to the acid-treated carbon nanotubes (AO-CNTs) based GC electrode. The unique structure endows N-STCs the enhanced electrochemical performance and promising applications in electrochemical sensing.

• 수산해양교육연구
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• 제18권1호
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• pp.58-64
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• 2006

In order to examine the effect of humidity on hydrogen embrittlement of STS 444 weld zone for boiler with dry and wet welding conditions, this paper was carried out the accelerated hydrogen osmosis test and the electrochemical Tafel polarization test. In 0.5M $H_2SO_4$ + 0.01M $As_20_3$ solution, this test is added to load of $1400kg/cm^2$ together with hydrogen osmosis by current of $50 {mA/cm^2}$ for 60 min.. The electrochemical Tafel polarization test was carried out in 0.5M $H_2SO_4$ + 0.01M $As_20_3$ solution. Therefore, the effect of humidity on hydrogen embrittlement of STS 444 was considered. The main results are as following: On the basis of hydrogen embrittlement mechanism, that is, integrated electrochemical polarization characteristics with the established mechanism of hydrogen embrittlement, the reduction rate of corrosion current density of weld zone in the wet weld condition is larger than in the dry condition. We can nondestructively predict the degree of hydrogen embrittlement of STS 444 weld zone for boiler through the reduction rate of electrochemical corrosion current density.

• 센서학회지
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• 제26권6호
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• pp.379-385
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• 2017

In this study, an amperometric non-enzymatic glucose sensor was developed on the surface of a glassy carbon electrode by simply drop-casting the synthesized homogeneous suspension of hexagonal boron nitride (h-BN) nanosheets with a copper metal-organic framework (Cu-MOF) composite. Comprehensive analytical methods, including field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry, were used to investigate the surface and electrochemical characteristics of the h-BN-Cu-MOF composite. The FE-SEM, FT-IR, and XRD results showed that the h-BN-Cu-MOF composite was formed successfully and exhibited a good porous structure. The electrochemical results showed a sensor sensitivity of $18.1{\mu}A{\mu}M^{-1}cm^{-2}$ with a dynamic linearity range of $10-900{\mu}M$ glucose and a detection limit of $5.5{\mu}M$ glucose with a rapid turnaround time (less than 2 min). Additionally, the developed sensor exhibited satisfactory anti-interference ability against dopamine, ascorbic acid, uric acid, urea, and nitrate, and thus, can be applied to the design and development of non-enzymatic glucose sensors.

• 상하수도학회지
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• 제28권5호
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• pp.541-548
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• 2014

The pickling brine generated from the salting process of kimchi production is difficult to treat biologically due to very high content of salt. When pickling brine is treated and discharged, it cannot satisfy the criteria for effluent water quality in clean areas, while resources such as the salt to be recycled and the industrial water are wasted. However, sterilization by ozone, UV and photocatalyst is expensive installation costs and operating costs when considering the small kimchi manufacturers. Therefore there is a need to develop economical process. The study was conducted on the sterilization efficiency of the pickling brine using electrochemical processing. The electrochemical treatment of organic matters has advantages over conventional methods such as active carbon absorption process, chemical oxidation, and biological treatment because the response speed is faster and it does not require expensive, harmful oxidizing agents. This study were performed to examine the possibility of electrochemical treatment for the efficient processing of pickling brine and evaluated the performance of residual chlorine for the microbial sterilization.

• Journal of Electrochemical Science and Technology
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• 제11권1호
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• pp.68-83
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• 2020

A fast and simple method for synthesis of Cu_xO-ZnO/PPy/RGO nanocomposite by electrochemical manner have been reported in this paper. For testing the utility of this nanocomposite we modified a GCE with the nanocomposite to yield a sensor for simultaneous determination of four analytes namely ascorbic acid (AA), dopamine (DA), uric acid (UA), and folic acid (FA). Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV) selected for the study. The modified electrode cause to enhance electron transfer rate so overcome to overlapping their peaks and consequently having the ability to the simultaneous determination of AA, DA, UA, and FA. To synthesis confirmation of the nanocomposite, Field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and electrochemical impedance spectroscopy (EIS) were applied. The linearity ranges were 0.07-485 μM, 0.05-430 μM, 0.02-250 μM and 0.022-180 μM for AA, DA, UA, and FA respectively and the detection limits were 22 nM, 10 nM, 5 nM and 6 nM for AA, DA, UA, and FA respectively Also, the obtained electrode can be used for the determination of the AA, DA, UA, and FA in human blood, and human urine real samples.

• Journal of Electrochemical Science and Technology
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• 제11권1호
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• pp.14-25
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• 2020

Li ion battery (LIB) is one of the most remarkable energy storage devices currently available in various applications. With a growing demand for high-performance batteries, the role of electrochemical analysis for batteries, especially, electrode reactions are becoming very important and crucial. Among various analytical methods, cyclic voltammetry (CV) is very versatile and widely used in many fields of electrochemistry. Through CV, it is possible to know electrochemical factors affecting the reaction voltage and reversibility, and furthermore, quantitative analysis on Li⁺ diffusivity as well as intercalation and capacitive reactions, and also anionic redox reaction. However, the explanation or interpretation of the results of CV is often deficient or controversial. In this mini-review, we briefly introduce the principle of cyclic voltammetry and its applications in LIB to bring a better understanding of the electrochemical reaction mechanisms involved in LIB.

• 한국수소및신에너지학회논문집
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• 제4권2호
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• pp.29-40
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• 1993

Intensive studies on the electrochemical characteristics of TiFe type alloy electrodes have been carried out to clarify the mechanism of electrochemical hydrogen absorption and desorption. It was found that electrochemical activation of the TiFe type alloys is difficult and that charge efficiencies are very low even after a decade of activation cycles. However, by the pretreatment of the powders such as gas activation and/or Ni chemical plating, charge efficiencies fairly increased, especially for the $TiFe_{0.8}Ni_{0.2}$ alloy. It was considered that difficulties to activation and lower charge efficies of the alloys are due to the presence of the passivation films, which prohibit inward diffusion of hydrogen and promote the combination of adsorbed hydrogen atom to gas bubbles during the electrochemical charge. In addition, lower diffusivity of hydrogen in the alloys may be played an important role lowering the charge efficiencies.

• Membrane and Water Treatment
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• 제9권3호
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• pp.189-194
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• 2018

Electrochemical reduction of nitrate was studied using Zn, Cu and (Ir+Ru)-Ti cathodes and Pt/Ti anode in a cell divided by an ion exchange membrane. During electrolysis, effects of the different cathode types on operating parameters (i.e., voltage, temperature and pH), nitrate removal efficiency and by-products (i.e., nitrite and ammonia) formation were investigated. Ammonia oxidation rate in the presence of NaCl was also determined using the different ratios of hypochlorous acid to ammonia. The operating parameter values were similar for all types of cathode materials and were maintained relatively constant. Nitrate was well reduced and converted mostly to ammonia using Zn and Cu cathodes. Ammonia, produced as a by-product of nitrate reduction, was oxidized in the presence of NaCl in the electrochemical process and the oxidation performance was enhanced upon increasing the hypochlorous acid-to-ammonia ratio to 1.09:1. Zn and Cu cathodes promoted the nitrate reduction to ammonia and the produced ammonia was finally removed from solution by reacting with hypochlorite ions. Using Zn or Cu cathodes, instead of noble metal cathodes, in the electrochemical process can be an alternative technology for nitrate-containing wastewater treatment.

• 한국군사과학기술학회지
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• 제14권4호
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• pp.740-746
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• 2011

Thermally activated batteries have good stability, reliability and long shelf life. Due to these characteristics and operational mechanism, thermal batteries are usually applied to military power sources. Especially, Li/$FeS_2$ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as electrolytes. The electrochemistry of thermal batteries have been researched for long time, however, electrochemical study using impedance spectroscopy was not published so much. Through this research, microscopic electrochemical research was investigated with electrochemical impedance spectroscopy(E.I.S). Electrolyte effects on Li/$FeS_2$ thermal battery was researched changing electrolytes, LiCl-KCl and LiBr-LiCl-LiF. Additionally, the salts, which are added to electrolytes, effects on thermal battery were researched. It is expected that the impedance spectroscopy analysis is applicable to not only thermal battery electrochemical study effectively, but also, thermal battery developments.

• 한국전기전자재료학회논문지
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• 제14권3호
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• pp.223-227
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• 2001

In this paper, the authors present the fabrication of high-yield Si thin-membranes by electrochemical etch-stop in tetramethyl ammonium hydroxide (TMAH): isopropyl alcohol (IPA):pyrazine solutions. The current-voltage (I-V) characteristics of n- and p-type Si in TMAH:IPA;pyrazine solutions were analysed, repsectively. Open circuit potential (OCP)and passivation potential (PP) of n- and p-type Si, respectively, were obtained and applied potential was selected between n- and p-type Si PPs. The electrochemical etch-stop method was applied to the fabrication of 801 micro-membranes with 20.0 $\mu\textrm{m}$ thickness on a 5" Si wafer. The average thickness of fabricated 801 micro-membranes on one wafer 20.03$\mu\textrm{m}$ and the standard deviation was ${\pm}$0.26$\mu\textrm{m}$. The Si surface of the etch-stopped micro-membranes was extremely flat with no noticeable taper or nonuniformity. The results indicate that use of the electrochemical etch-stop method for the etching of Si in TMAH:IPA;pyrazine solutions provides a powerful and versatile alternative process for fabricating high-yield Si micro-membranes.