• Prospectives of Industrial Chemistry
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• v.24 no.4
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• pp.1-21
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• 2021

화석연료의 과도한 사용으로 유발된 기후변화 문제를 해결하기 위해 대체에너지의 개발에 대한 관심이 높아지고 있는 가운데 재생가능하며 친환경적인 수소에너지가 실현가능한 궁극적 대안으로 주목받고 있다. 다양한 수소 생산 기술 중 물의 전기분해를 이용한 수전해 기술은 온실가스와 같은 오염물질을 배출하지 않으며 재생에너지와 연계하여 미이용 전력을 대용량 장주기로 저장할 수 있다는 장점이 있다. 수전해 장치는 수소와 산소를 발생하는 전극과 기체의 섞임을 방지하고 이온을 전달하는 분리막으로 구성되며 그 중 분리막은 수전해 장치의 효율과 안정성을 결정짓는 핵심 부품이다. 본 총설에서는 수전해 기술 중 저온 수전해에 해당하는 알칼라인 수전해(alkaline water electrolysis), 고분자전해질막 수전해(polymer electrolyte membrane water electrolysis)와 음이온교환막 수전해(anion exchange membrane water electrolysis)에 사용되는 분리막에 대한 특성을 분석하고 최근 연구 동향에 대해서 다루고자 한다.

• Korean Journal of Materials Research
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• v.22 no.2
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• pp.86-90
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• 2012

Insoluble catalytic electrodes were fabricated by RF magnetron sputtering of Pt on Ti substrates and the performance of seawater electrolysis was compared in these electrodes to that is DSA electrodes. The Pt-sputtered insoluble catalytic electrodes were nearly 150 nm-thick with a roughness of $0.18{\mu}m$, which is 1/660 and 1/12 of these values for the DSA (dimensionally stable anodes) electrodes. The seawater electrolysis performance levels were determined through measurements of the NaOCl concentration, which was the main reaction product after electrolysis using artificial seawater. The NaOCl concentration after 2 h of electrolysis with artificial seawater, which has 3.5% NaCl normally, at current densities of 50, 80 and 140 mA/$cm^2$ were 0.76%, 1.06%, and 2.03%, respectively. A higher current density applied through the electrodes led to higher electrolysis efficiency. The efficiency reached nearly 58% in the Pt-sputtered samples after 2 h of electrolysis. The reaction efficiency of DSA showed higher values than that of the Pt-sputtered insoluble catalytic electrodes. One plausible reason for this is the higher specific surface area of the DSA electrodes; the surface cracks of the DSAs resulted in a higher specific surface area and higher reaction sites. Upon the electrolysis process, some Mg- and Ca-hydroxides, which were minor components in the artificial seawater, were deposited onto the surface of the electrodes, resulting in an increase in the electrical resistances of the electrodes. However, the extent of the increase ranged from 4% to 7% within an electrolysis time of 720 h.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.951-954
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• 2000

This paper presents a new cutting method, i.e. diamond cutting, aided by electrolysis, in order to cut ferrous materials with diamond tools. Diamond cutting is widely applied in manufacturing ultraprecision parts such as magnetic disk, polygon mirror, spherical/non-spherical mirror and copier drum, etc. because of the diamond tool edge sharpness. In general, however, diamond cutting cannot be applied to cutting steels, because diamond tools wear excessively in cutting iron based materials like steel due to their high chemical interaction with iron in high temperature. In order to suppress the diffusion of carbon from the diamond tool and to reduce increase of cutting force due to size effect, we attempt to change chemically the compositions of iron based materials using electrolysis in a limited part which will be soon cut. Through experiments under several micro-machining and electrolysis conditions, cutting using electrolysis, compared to conventional cutting, was found to result in a great decrease of the cutting force, a better surface and much less wear tool.

• KSBB Journal
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• v.25 no.1
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• pp.33-40
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• 2010

Conventional disinfectants and disinfection method are expensive, hazardous and often require long periods of exposure. Recently, there is growing interest in complex disinfection process as a disinfection technique in medical instruments such as endoscope, hand piece bur to improve the disinfection efficiency and conveniency. The aim of this study was to evaluate the performance of a new complex process for the purpose of disinfection of Escherichia coli in water. Three single process (electrolysis, UV and ultrasonic process) was combined dual and triple disinfection process. The order of disinfection performance for E. coli in dual process lie in: Electrolysis + UV > Electrolysis + Ultrasonic > UV + Ultrasonic process. Disinfection efficiency of E. coli and degradation of N, N-Dimethyl-4-nitrosoaniline (RNO, indicating material of OH radical formation) of dual process was higher than that of the triple process (Electrolysis + UV + Ultrasonic process). In electrolysis + UV process, disinfection tendency was well agreed with RNO degradation tendency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.617-620
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• 1999

To reduce the consumption of chemicals and ultra pure water(UPW) in cleaning process used in device manufacturing, we proposed wet processes that use electrolytic ionized water(EIW), which is generated by electrolysis of a diluted electrolyte solution or UPW and systemically investicate the EIW\`s characteristics. EIW\`s pH values are increased in cathode chamber and decreased in anode chamber according to the electrolysis time and its varied ratio is reduced with time increasement. The variation of pH and ORP is increased accordin to the applied voltage until critical voltage. But more than that voltage, the variation is decreased because of ion\`s scattering effect. When electrolyte is added, the effects of electrolysis is increased because electrolyte acts as catalyst. But when the density of electrolyte is increased more than critical value, ion\`s flowage is obstructed and the effects of electrolysis is decreased.

• Membrane Journal
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• v.27 no.6
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• pp.477-486
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• 2017

Hydrogen is one of energy storage systems, which could be transfer from electric energy to chemical energy or from chemical energy to electric energy, and is as an energy carrier. Water electrolysis is being investigating as one of the hydrogen production methods. Recently, water electrolysis receive attention for the element technology in PTG (power to gas) and PTL (power to liquid) system. In this paper, it was explained the principle and type for the water electrolysis, and recent research review for the alkaline water electrolysis.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.389-398
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• 2019

Hydrogen energy is not only a solution to climate change problems caused by the use of fossil fuels, but also as an alternative source for the industrial power generation and automotive fuel. Among hydrogen production methods, electrolysis of water is considered to be one of the most efficient and practical methods. Compared to that of the fossil fuel production method, the method of producing hydrogen directly from water has no emission of methane and carbon dioxide, which are regarded as global environmental pollutants. In this paper, the alkaline water electrolysis (AWE) and polymer electrolyte membrane water electrolysis (PEMWE), which are one of the hydrogen production methods, were discussed. Recent research trends of hydrocarbon electrolyte membranes and the crossover phenomenon of electrolyte membranes were also described.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.899-904
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• 2016

ELID grinding is an excellent technique for the mirror grinding of the variety of the advanced metallic or nonmetallic materials. The focus of this study is the development of an automatic-control electrolysis-speed device for the automation of the ELID-grinding process. For the development of the automatic-control electrolysis-speed device, analysis experiments regarding the ELID cycle and oxide-layer removal and creation were conducted according to a truing and dressing process. Also, a comparative experiment was conducted to confirm the variance of the electrolysis speed in accordance with changes of the voltage. The experiment results for the developed automatic-control electrolysis-speed device show that the developed device could control the electrolysis speed according to voltage changes through the use of the data that are monitored during the ELID-grinding process.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.1
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• pp.1-10
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• 2021

Water electrolysis technology, which generates hydrogen using renewable energy resources, has recently attracted great attention. Especially, the polymer electrolyte membrane water electrolysis system has several advantages over other water electrolysis technologies, such as high efficiency, low operating temperature, and optimal operating point. Since research that analyzes performance characteristics using test bench have high cost and long test time, however, model based approach is very important. Therefore, in this study, a system model for water electrolysis dynamics of a polymer electrolyte membrane was developed based on MATLAB/Simulink®. The water electrolysis system developed in this study can take into account the heat and mass transfer characteristics in the cell with the load variation. In particular, the performance of the system according to the stack temperature control can be analyzed and evaluated. As a result, the developed water electrolysis system can analyze water pump dynamics and hydrogen generation according to temperature dynamics by reflecting the dynamics of temperature.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.695-700
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• 2014

Proton Exchange Membrane Fuel Cells (PEMFC) can generate hydrogen and oxygen from water by electrolysis. But the electrode and polymer electrolyte membrane degrade rapidly during PEM water electrolysis because of high operation voltage over 1.7V. In order to reduce the rate of anode electrode degradation, unsupported $IrO_2$ catalyst was used generally. In this study, Pt/C catalyst for PEMFC was used as a water electrolysis catalyst, and then the degradation of catalyst and membrane were analysed. After water electrolysis reaction in the voltage range from 1.8V to 2.0V, I-V curves, impedance spectra, cyclic voltammograms and linear sweep voltammetry (LSV) were measured at PEMFC operation condition. The degradation rate of electrode and membrane increased as the voltage of water electrolysis increased. The hydrogen yield was 88 % during water electrolysis for 1 min at 2.0V, the performance at 0.6V decreased to 49% due to degradation of membrane and electrode assembly.