• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.466-473
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• 2020

Fabric current collector can be a promising electrode material for Capacitive Deionization (CDI) system that can achieve energy-efficient desalination of water. The one of the most attractive feature of the fabric current collector is its high tensile strength, which can be an alternative to the low mechanical strength of the graphite foil electrode. Another advantage is that the textile properties can easily make shapes by simple cutting, and the porosity and inter-fiber space which can assist facile flow of the aqueous medium. The fibers used in this study were made of woven structures using a spinning yarn using conductive LM fiber and carbon fiber, with tensile strength of 319 MPa, about 60 times stronger than graphite foil. The results were analyzed by measuring the salt removal efficiency by changing the viscosity of electrode slurry, adsorption voltage, flow rate of the aqueous medium, and concentration of the aqueous medium. Under the conditions of NaCl 200 mg/L, 20ml/min and adsorption voltage 1.5 V, salt removal efficiency of 43.9% in unit cells and 59.8% in modules stacked with 100 cells were shown, respectively. In unit cells, salt removal efficiency increases as the adsorption voltage increase to 1.3, 1.4 and 1.5 V. However, increasing to 1.6 and 1.7 V reduced salt removal efficiency. However, the 100-cell-stacked module showed a moderate increase in salt removal efficiency even at voltages above 1.5 V. The salt removal rate decreased when the flow rate of the feed was increased, and the salt removal rate decreased when the concentration of the feed was increased. This work shows that fabric current collector can be an alternative of a graphite foil.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.527-532
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• 2005

Ionic polymer metal composites (IPMC) are soft polymeric smart materials having large displacement at low voltage in air and water. The polymeric electrolyte actuator consists of a thin and porous membrane and metal electrodes plated on both faces, in impregnation electro-plating method. The response and actuation of actuator are governed. Among many factors governing the activation and response of IPMC actuator, the surface electrode plays an important role. In this study, the well-designed modification of electrode surface was carried out in order to improve the chemical stability well as electromechanical characteristics of the IPMC actuator. We employed Ion Beam Assisted Deposition (IBAD) method to prepare the topologically homogeneous thin surface electrode. After roughing the surface of Nafion membrane in order to get a larger surface area, the IPMC was prepared by impregnation for electro-plating and re- coating on the surface through traditional chemical deposition, followed by an additional surface treatment with high conductive metals with IBAD. It was observed that our IPMC specimen shows the enhanced surface electrical properties as well as the improved actuation and response characteristics under applied electric field.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.230-239
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• 1992

Nickel was used as a catalyst for the hydrogen electrode in alkaline fuel cell. The optimum electrolyte concentration and recommendable operating temperature identified from polarization curves were 6N KOH and $80^{\circ}C$, respectively. Comparing the conductivity, apparent porosity and current density at porous hydrogen electrode manufactured with various PTFE additions, the proper content of PTFE was 10wt%. Chemisorption was carried out to define the appropriate surface area. The electrode produced with 10wt% of PTFE and sintered at $340^{\circ}C$ showed more than $200mA/cm^2$ of current density. The morphology of electrode surface was investigated with SEM. Cold pressing, hot pressing, rolling and calendering methods were carried out for manufacturing the electrode, and electrochemical characteristics for each method was studied.

• Membrane Journal
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• v.24 no.4
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• pp.332-339
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• 2014

In this study, an anion-exchange ionomer solution was developed by employing poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) as the base material for the improvement of the capacitive deionization (CDI) performances. It was found that prepared quaternized PPO (QPPO) exhibited excellent ion conductivity superior to that of a commercial anion-exchange membrane (AMX, Astom Corp., Japan) and also the electrochemical properties were shown to be comparable with each other. The CDI tests were conducted by employing the porous carbon electrode coated with the ionomer solution and the result showed the high salt removal efficiency of about 94.9%. By comparing the desalination efficiencies in conventional CDI, membrane CDI (MCDI) with a commercial anion-exchange membrane, and coated CDI (CCDI) employing the porous carbon electrode coated with QPPO, it was confirmed that CCDI shows the high salt removal performance improved by 52.1% and 18.3% compared with those of conventional CDI and MCDI, respectively.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.36-44
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• 2015

This article describes synthesis and electrochemical properties of layer-by-layer self-assembled multilayer film composed of polyaniline (PANi), graphene oxide (GO) and phytic acid (PA), whereby the GO was electrochemically reduced to ERGO, resulting in $(PANi/ERGO/PANi/PA)_{10}$ film electrode. Especially, we examined the possibility to improve the volumetric capacitive property of $(PANi/ERGO)_{20}$ film electrode via combining a spherical hexakisphosphate PA nanoparticle into the multilayer film that would dope PANi properly and also increase the porosity and surface area of the electrode. The electrochemical performances of the multilayer film electrodes were investigated using a three-electrode configuration in 1 M $H_2SO_4$ electrolyte. As a result, the $(PANi/ERGO)_{20}$ electrode showed the volumetric capacitance of $666F/cm^3$ at a current density of $1A/cm^3$, which was improved to the volumetric capacitance of $769F/cm^3$ for the $(PANi/ERGO/PANi/PA)_{10}$ electrode, in addition to the cycling stability maintained to 79.3% of initial capacitance after 1000 cycles. Thus, the electrochemical characteristics of the $(PANi/ERGO)_{20}$ electrode, which was densely packed by ${\pi}-{\pi}$ stacking between the electron-rich conjugate components, could have been improved through structural modification of the multilayer film via combining a spherical hexakisphosphate PA nanoparticle into the multilayer film.

• Membrane Journal
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• v.25 no.1
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• pp.60-66
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• 2015

To investigate the performance of the composite carbon electrodes which the ion exchange polymers were directly casted onto porous carbon electrode surfaces, the adsorption/desorption experiments were carried out by varying the feed concentration, feed flow rate, and desorption voltages for the NaCl solution. When the feed concentration was 100 mg/L, the increase of the adsorption time led to the increase of the salt removal due to the increase of the residence time inside the cell while the increase of the feed flow rate from 15 mL/min to 23 mL/min gave the decrease of the salt removal efficiency, 12% because of the short residence time. When the feed concentration was 200 mg/L, the salt removal was shown 10~15% low because of the incomplete desorption within the desorption intervals.

• Journal of the Korean Electrochemical Society
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• v.22 no.1
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• pp.1-12
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• 2019

The reduction of nitrogen to produce ammonia has been attracting much attention as a renewable energy technology. Ammonia is the basis for many fertilizers and is also considered an energy carrier that can power internal combustion engines, diesel engines, gas turbines, and fuel cells. Traditionally, ammonia has been produced through the Haber-Bosch process, in which atmospheric nitrogen combines with hydrogen at high temperature ($350-550^{\circ}C$) and high pressure (150-300 bar). This process consumes 1-2% of current global energy production and relies on fossil fuels as an energy source. Reducing the energy input required for this process will reduce $CO_2$ emissions and the corresponding environmental impact. For this reason, developing electrochemical ammonia-production methods under ambient temperature and pressure conditions should significantly reduce the energy input required to produce ammonia. In this review, we introduce the electrochemical nitrogen reduction reaction at ambient condition. Numerical studies on the electrochemical nitrogen reduction mechanism have been carried out through the computation of density function theory. Electrodes such as nanowires and porous electrodes have been also actively studied for further participation in electrochemical reactions.

• Prospectives of Industrial Chemistry
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• v.14 no.6
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• pp.21-28
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• 2011

이온교환막을 이용한 전기적 탈염기술은 막모듈 내에 양이온교환막과 음이온교환막을 교대로 장착시키고 모듈의 양단 전극에 전압을 적용함으로써 물속에 용존되어 있는 양이온과 음이온들을 전기의 힘을 이용하여 선택적으로 투과시키는 원리를 기반으로 하는 청정공정 기술이다. 이온교환막 공정은 전통적으로 산/알칼리의 생산, 산업폐수의 중금속의 제거, 해수의 담수화, 반도체 산업의 초순수의 제조, 해수에서 식염의 제조, 발효산업의 유기산 및 아미노산의 회수 등 다양한 산업분야에서 응용되어 왔다. 최근에는 이러한 기존의 응용분야에서 벗어나 새롭게 응용분야가 넓어지고 있다. 이온교환막과 다공성 탄소전극을 결합한 막축전식 해수담수화기술, 해수와 담수의 염도차를 이용한 역전기투석식 해수발전 등의 새로운 선택분리기능 및 응용분야를 가진 이온교환막의 개발 및 공정에 관한 연구가 활발히 이루어지고 있다. 그러나 국내에서는 이온교환막이 아직 상용화되지 않고 있어 이온교환막을 이용한 응용연구가 활발하게 진행되지 못하고 있어 그 개발이 시급하다. 본 논문에서는 먼저 이온교환막을 이용한 전기투석식 탈염기술, 물분해 전기투석, 전기탈이온 공정에 관한 동향을 조사하였다. 아울러 미래의 이온교환막의 응용기술인 해수담수화기술로서 역삼투법과 경쟁하여 에너지를 낮게 소모할 것으로 예상되는 분리막을 이용한 막축전식 탈염기술과 무한한 신재생에너지원인 해수와 담수를 이용한 역전기투석 해수발전기술에 대해 기술의 원리들과 최근의 연구동향 등을 정리하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.92.2-92.2
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• 2018

빠르고 정확한 글루코오스 농도 측정은 의료, 식품, 환경 등 다양한 산업에서 매우 중요하다. 글루코오스 산화효소를 기반으로 하는 현재 글루코오스 센서는 높은 감도와 선택성을 갖지만 온도변화나 다른 화학물 등 환경에 취약하다는 단점이 있다. 따라서 최근 비효소식 글루코오스 센서에 대한 연구가 활발히 진행되고 있다. 금속-유기 구조체(MOFs)는 금속이온과 유기물 리간드로 구성된 결정성 다공체로, 큰 기공 크기와 비표면적, 안정성 등을 특징으로 갖는다. 대부분의 MOFs는 전기전도도가 낮지만 금속이온의 산화/환원, 리간드의 화학적 개질을 통해 전기화학분야에서도 다양하게 연구되고 있다. 본 연구에서는 글루코오스 농도 측정을 위한 전극촉매로 다양한 금속이온과 리간드로 이루어진 MOFs를 합성했다. 표면분석을 통해 MOFs의 전기화학적 처리 전후의 구조와 성질 변화를 관찰했고 전기화학적 분석을 통해 금속이온과 리간드의 종류가 감도, 선택성 등 글루코오스 검지 성능에 주는 영향을 분석했다. 그 결과 Ni, Co 기반의 MOFs가 글루코오스에 대해 높은 감도를 보였으며 이를 통해 MOFs의 글루코오스 센서로의 응용 가능성을 확인했다.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.153-157
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• 2017

Gel type internal electrolytes were synthesized by varying hydroxyethyl-cellulose (HEC) amounts and their durability and conductivity were measured. The ionic conductivity decreased as the content of HEC increased thus the internal electrolyte containing more than 12% of HEC could not be used as a reference electrode. Based on durability test results, as the HEC amount decreased carrier density resulting in increasing of the amount of KCl coming out of the porous membrane. Therefore in order to use long time at ballast water treatment systems, we selected 10% HEC for gel type internal electrolyte. The resolution test for total residual oxidants (TRO) was carried out using the TRO sensor and the gel type reference electrode made of 10% HEC. A 50 mV potential was applied to the TRO sensor for 30 sec and changes in the current were measured. It was confirmed that the TRO concentrations ranging from 0 to 15 mg/L could be separated at salinity conditions of 0.2~30 PSU. The results indicated that the TRO concentration at sea water and at fresh water was successfully measured by the TRO sensor constructed with the reference electrode using gel-type internal electrolyte of HEC.