• Journal of Electrochemical Science and Technology
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• 제8권3호
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• pp.250-256
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• 2017

A graphene electrode with a novel in-plane structure is proposed and successfully adopted for use in supercapacitor applications. The in-plane structure allows electrolyte ions to interact with all the graphene layers in the electrode, thereby maximizing the utilization of the electrochemical surface area. This novel structure contrasts with the conventional out-of-plane stacked structure of such supercapacitors. We herein compare the volumetric capacitances of in-plane- and out-of-plane-structured devices with reduced multi-layer graphene oxide films as electrodes. The in-plane-structured device exhibits a capacitance 2.5 times higher (i.e., $327F\;cm^{-3}$) than that of the out-of-plane-structured device, in addition to an energy density of $11.4mWh\;cm^{-3}$, which is higher than that of lithium-ion thin-film batteries and is the highest among in-plane-structured ultra-small graphene-based supercapacitors reported to date. Therefore, this study demonstrates the potential of in-plane-structured supercapacitors with high volumetric performances as ultra-small energy storage devices.

• Carbon letters
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• 제12권4호
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• pp.252-255
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• 2011

Carbon-based electric double-layer capacitors are being evaluated as potential energy-storage devices in an expanding number of applications. In this study, samples of carbon black (CB) treated at different temperatures ranging from $650^{\circ}C$ to $1100^{\circ}C$ were used as electrodes to improve the efficiency of a capacitor. The surface properties of the heat-treated CB samples were characterized by X-ray photoelectron spectroscopy and X-ray diffraction. The effect of the heat-treatment temperature on the electrochemical behaviors was investigated by cyclic voltammetry and in galvanostatic charge-discharge experiments. The experimental results showed that the crystallinity of the CBs increased as the heat-treatment temperature increased. In addition, the specific capacitance of the CBs was found to increase with the increase in the heat-treatment temperature. The maximum specific capacitance was 165 $F{\cdot}g-1$ for the CB sample treated at $1000^{\circ}C$.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.11.1-11.1
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• 2010

As one of the non-vacuum, low temperature fabrication route, electrochemical synthesis has been focused for pursuing the cost-effective pathway to produce high efficiency photovoltaic devices. Especially the availability to form the thin film structure on flexible substrate would be the great advantage of electrochemical process. The successful synthesis of the most favorable absorber materials such as CdTe and CIGS has been reported by many researchers, however, the efficiency of electrochemically synthesized could not exceed that from vacuum process, because of microstructural controllability and compositional variation on devices. In this study, we represent the effect of process parameters on the microstructure and composition of compound semiconductor during the synthesis, and propose the photovoltaic characteristics of electrochemically synthesized solar cells.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.19-20
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• 2011

• 한국환경과학회지
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• 제22권9호
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• pp.1073-1078
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• 2013

This paper presents the results of the electrochemical treatment of chemical oxygen demand(COD) and total nitrogen(T-N) compounds in the wastewater generated from flue gas desulfurization process by using a lab-scale electrolyzer. With the increase in the applied current from 0.6 Ah/L to 1.2 Ah/L, the COD removal efficiency rapidly increases from 74.5% to 96%, and the T-N removal efficiency slightly increases from 37.2% to 44.9%. Therefore, it is expected that an electrochemical treatment technique will be able to decrease the amount of chemicals used for reducing the COD and T-N in wastewater of the desulfurization process compared to the conventional chemical treatment technique.

• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.52-57
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• 2016

Nanoporous-layer-covered TiO₂ nanotube arrays (Type II TNTs) were fabricated by two-step electrochemical anodization. For comparison, conventional TiO₂ nanotube arrays (Type I TNTs) were also prepared by one-step electrochemical anodization. Types I and II TNTs were detached by selective etching and then transferred successfully to a transparent F-doped SnO₂ (FTO) substrate by a sol-gel process. Both FTO/Types I and II TNTs allowed front side illumination to exhibit incident photon-to-current efficiencies (IPCEs) in the long wavelength region of 300 to 750 nm without the absorption of light by the iodine-containing electrolyte. The Type II TNT exhibited longer electron lifetime and faster charge transfer than the Type I TNT because of its relatively fewer defect states. These beneficial effects lead to a high overall energy conversion efficiency (5.32 %) of the resulting dye-sensitized solar cell.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.179-184
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• 2016

The interface between the surface of a cathode material and the electrolyte gives rise to surface reactions such as solid electrolyte interface (SEI) and chemical side reactions. These reactions lead to increased surface resistance and charge transfer resistance. It is consequently necessary to improve the electrochemical characteristics by suppressing these reactions. In order to suppress unnecessary surface reactions, we coated cathode material using polypropylene (PP). The PP coating layer effectively reduced the SEI film that is generated after a 4.3 V initial charging process. By mitigating the formation of the SEI film, the PP-coated Li[(Ni_0.6Co_0.1Mn_0.3)_0.36(Ni_0.80Co_0.15Al0.05)_0.64)]O₂(NCS) electrode provided enhanced transport of Li⁺ ions due to reduced SEI resistance (R_SEI) and charge transfer resistance (R_ct). The initial charge and discharge efficiency of the PP-coated NCS electrode was 96.2 % at a current density of 17 mA/g in a voltage range of 3.0 ~ 4.3 V, whereas the efficiency of the NCS electrode was only 94.7 %. The presence of the protective PP layer on the cathode improved the thermal stability by reducing the generated heat, and this was confirmed via DSC analysis by an increased exothermic peak.

• Tribology and Lubricants
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• 제37권6호
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• pp.213-223
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• 2021

Electrochemical mechanical planarization (ECMP) was developed to overcome the shortcomings of conventional chemical mechanical planarization (CMP). Because ECMP technology utilizes electrochemical reactions, it can have a higher efficiency than CMP even under low pressure conditions. Therefore, there is an advantage in that it is possible to reduce dicing and erosions, which are physical defects in semiconductor CMP. This paper summarizes the papers on ECMP published from 2003 to 2021 and analyzes research trends in ECMP technology. First, the material removal mechanisms and the configuration of the ECMP machine are dealt with, and then ECMP research trends are reviewed. For ECMP research trends, electrolyte, processing variables and pads, tribology, modeling, and application studies are investigated. In the past, research on ECMP was focused on basic research for the development of electrolytes, but it has recently developed into research on tribology and process variables and on new processing systems and applications. However, there is still a need to increase the processing efficiency, and to this end, the development of a hybrid ECMP processing method using another energy source is required. In addition, ECMP systems that can respond to the developing metal 3D printing technology must be researched, and ECMP equipment technology using CNC and robot technology must be developed.

• Corrosion Science and Technology
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• 제22권5호
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• pp.314-321
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• 2023

The aim of the present study was to investigate the effect of thymus extract on corrosion inhibition of aluminum 5083 alloy in a 0.1 M NaCl medium prepared using a mixture of ethylene glycol and water using potentiodynamic and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic electrochemical technique showed an increase in corrosion inhibition efficiency starting from 49.63% at a concentration of 0.25 g/L to 92.71% at a maximum concentration of 1.25 g/L of the extract. These results were consistent with those obtained via EIS analysis. Spectral characterization of the tested plant extract using the Fourier-transform infrared spectroscopy (FTIR) technique confirmed the presence of organic compounds having different oxygen and aromatic functionalities in the extract that could help enhance the adsorption of these compounds on the aluminum surface. This study reveals possible adsorption isotherm of the thymus extract on the aluminum surface, supporting a Langmuir isotherm for the adsorption of inhibitor molecules on this surface.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.206-213
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• 2019

The development of simple methods for As detection has received great attention because As is a toxic chemical element causing environmental and health-related issues. In this work, the effect of nanostructures of Au electrodes on their electroanalytical performance during As detection was investigated. Different Au nanostructures with various surface morphologies such as nanoplate Au, nanospike Au, and dendritic Au structures were prepared, and their electrochemical behaviors toward square-wave anodic stripping voltammetric As detection were examined. The difference in intrinsic efficiency for As detection between nanostructured and flat Au electrodes was explained based on the crystallographic orientations of Au surfaces, as examined by the underpotential deposition of Pb. The most efficient As detection performance was obtained with nanoplate Au electrodes, and the effects of the pre-deposition time and interference on As detection of the nanoplate Au electrodes were also investigated.