• 한국수소및신에너지학회논문집
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• 제18권4호
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• pp.391-398
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• 2007

The covalently cross-linked sulfonated polyetheretherketone (CL-SPEEK) membrane was prepared by four-step synthesis of sulfonation-sulfochlorination, partial reduction, lithiation, and cross-linking, and its electrochemical and mechanical properties were investigated for water electrolysis application. The prepared ion exchange membranes showed good electrochemical and mechanical properties; proton conductivity of 0.116 S/cm at $80^{\circ}C$, water uptake of 44.6%, ion exchange capacity of 1.75 meq/g-dry-memb., tensile strength of 64.25 MPa and elongation of 61.11%. The membrane electrode assembly (MEA) with homemade membranes were prepared by non-equilibrium impregnation-reduction (I-R) method. Especially, the electrochemical surface area (ESA) and roughness factor of CL-SPEEK electrolyte by cyclic voltammetry method were 23.46 $m^2/g$ and 307.3 $cm^2-Pt/cm^2$, respectively. The prepared MEA was used in the unit cell of water electrolysis and the cell voltage was 1.81 V at 1 A/$cm^2$ and $80^{\circ}C$, with platinum loadings of 1.31 mg/$cm^2$.

• 공업화학
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• 제26권5호
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• pp.598-603
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• 2015

본 연구에서는 전기이중층 커패시터의 비정전용량 향상시키기 위하여 활성탄소섬유의 열처리 온도가 전기화학적 특성에 미치는 영향을 알아보았다. 용융방사한 피치 섬유를 안정화를 거쳐 $800^{\circ}C$에서 4 M KOH로 활성화하였고, 활성화 섬유를 각각 1050, $1450^{\circ}C$의 온도조건에서 열처리하여 서로 다른 특성을 갖는 활성탄소섬유를 제조하였다. 제조된 활성탄소섬유는 열처리 온도가 증가함에 따라 비표면적이 $828m^2/g$에서 $987m^2/g$으로 증가하였으며 미세공 및 중간세공의 부피 또한 증가하였다. 이는 열처리 공정이 활성탄소섬유 내부의 산소 및 수소 원소 성분을 탈리시키면서 세공이 생성되고, 활 성탄소섬유를 수축하게 하여 상대적으로 세공의 크기를 증가시켰기 때문이다. 이러한 세공 변화로 인하여 제조된 전극은 1 M 황산수용액을 전해질로 하여 5 mV/s의 전위주사속도로 측정하였을 때, 비정전용량이 73 F/g에서 119 F/g으로 향상되었음을 확인하였다.

• 자원리싸이클링
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• 제21권5호
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• pp.31-37
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• 2012

실리콘 웨이퍼공정에서 발생하는 실리콘 슬러지로부터 실리콘 및 탄화규소를 분리한 다음, 전해법으로 원소형태의 실리콘을 회수하는 연구를 수행하였다. 실리콘 슬러지의 주요 불순물은 절삭유, 금속불순물, 실리콘 및 실리콘 카바이드를 들 수 있다. 기계적 선별법으로 분리한 실리콘, 탄화실리콘 복합물을 $1000^{\circ}C$에 1시간동안 염화 배소하여 응축하고 회수한 사염화실리콘을 이온성액체인 $[Bmpy]Tf_2N$에 용해하여 전해액으로 사용하였다. 순환전위법으로부터 $[Bmpy]Tf_2N$의 안정한 전압구간과 사염화실리콘을 용해한 $[Bmpy]Tf_2N$ 전해액에서 실리콘의 환원으로 추정되는 환원피크를 얻을 수 있었다. 정전위법(-1.9 V vs. Pt-QRE)에서 1시간동안 금 전극 상에 전해한 다음, 전극표면을 XRD, SEM-EDS 및 XPS 분석을 통하여 실리콘이 원소형태로 전착되었음을 확인하였으며, 미량의 산소가 검출되는 것은 분석과정에서 시편이 공기 중에 노출되었기 때문으로 판단된다.

• 분석과학
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• 제13권2호
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• pp.173-178
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• 2000

두 개의 페놀기를 포함하는 열린 고리형태의 1, 14-Bis(2-hydroxybenzyl)-2, 6, 9, 12-tetraazatetradecane(bsated) 리간드를 염산염의 형태로 분리하여 원소 분석, 질량 스펙트럼 및 핵자기공명법으로 분석하였다. 합성된 리간드의 산 해리상수($logK^n{_H}$)와 $Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$ 및 $Zn^{2+}$에 대한 안정도 상수($logK_{ML}$)를 전위차 적정법으로 결정하였다. 이때 온도는 $25^{\circ}C$ 및 이온강도는 0.10M($KNO_3$)로 고정시켰다. [Cu(bsated)] $(ClO_4)_2$ X-ray구조의 crystal data는 다음과 같다: Monoclinic space group $P2_1/n$, $a=17.856(4){\AA}$, $b=17.709(1){\AA}$, $c=8.539(2){\AA}$, $V=2700(2){\AA}$ with Z=4. tetrabutylammonium perchlorate 전해질의 dimethyl sulfoxide 용액속에서 [Cu(bsated)]$(ClO_4)_2$ 착물의 전기화학적 특성을 순환 전압-전류법 (CV)과 normal pulse voltammertry (NPV, 정상펄스전압전류법)으로 측정하였다.

• 분석과학
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• 제29권1호
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• pp.35-42
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• 2016

A new nano-composite carbon ink for the development of disposable dopamine (DA) biosensors based on screen-printed carbon electrodes (SPCEs) is introduced. The method developed uses SPCEs coupled with a tyrosinase modified nano-composite carbon ink. The ink was prepared by an “in-house” procedure with reduced graphene oxide (rGO), Pt nanoparticles (PtNP), and carbon materials such as carbon black and graphite. The rGO-PtNP carbon composite ink was used to print the working electrodes of the SPCEs and the reference counter electrodes were printed by using a commercial Ag/AgCl ink. After the construction of nano-composite SPCEs, tyrosinase was immobilized onto the working electrodes by using a biocompatible matrix, chitosan. The composite of nano-materials was characterized by X-ray photoelectron spectroscopy (XPS) and the performance characteristics of the sensors were evaluated by using voltammetric and amperometric techniques. The cyclic voltammetry results indicated that the sensors prepared with the rGO-PtNP-carbon composite ink revealed a significant improvement in electro-catalytic activity to DA compared with the results obtained from bare or only PtNP embedded carbon inks. Optimum experimental parameters such as pH and operating potential were evaluated and calibration curves for dopamine were constructed with the results obtained from a series of amperometric detections at −0.1 V vs. Ag/AgCl. The limit of detection was found to be 14 nM in a linear range of 10 nM to 100 µM of DA, and the sensor’s sensitivity was calculated to be 0.4 µAµM⁻¹cm⁻².

• Journal of Electrochemical Science and Technology
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• 제10권4호
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• pp.394-401
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• 2019

The unique study of TiO₂ sol-gel modified carbon paste electrode (CPE) nanocomposites have been developed for electrochemical sensor detecting fipronil pesticide compound. We develop the easy synthesized TiO₂ via a sol-gel method and modified in CPE which applied electrochemical system as cyclic voltammetry (CV) because the concentration is proportional with current peaks. We discover the TiO₂ optimal mass used of 0.1 g which is compared with 0.7 g carbon and 0.3 mL paraffin. It has high-current anodic (Ip_a) of 1.13×10³ μA and high-current cathodic (Ip_c) -0.96×10³ μA in scan rate of 0.5 V/s. The limit of detection (LOD) of fipronil has been determined of 34.0×10^-5 μM in percent recovery of 0.8%. Its high-stability for lifetime TiO₂-CPE nanocomposites was expressed for 13 days which mean that can be used for detecting fipronil pesticide.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2185-2189
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• 2010

Closely arranged CdSe and Zn doped CdSe vertical nanorod bundles were grown directly on FTO coated glass by using electrodeposition method. Structural analysis by XRD showed the hexagonal phase without any precipitates related to Zn. FE-SEM image showed end capped vertically aligned nanorods arranged closely. From the UV-vis transmittance spectra, band gap energy was found to vary between 1.94 and 1.98 eV due to the incorporation of Zn. Solar cell parameters were obtained by assembling photoelectrochemical cells using CdSe and CdSe:Zn photoanodes, Pt cathode and polysulfide (1M $Na_2S$ + 1M S + 1M NaOH) electrolyte. The efficiency was found to increase from 0.16 to 0.22 upon Zn doping. Electrochemical impedance spectra (EIS) indicate that the charge-transfer resistance on the FTO/CdSe/polysulfide interface was greater than on FTO/CdSe:Zn/polysulfide. Cyclic voltammetry results also indicate that the FTO/CdSe:Zn/polysulfide showed higher activity towards polysulfide redox reaction than that of FTO/CdSe/polysulfide.

• 한국수소및신에너지학회논문집
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• 제28권5호
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• pp.471-480
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• 2017

A proton exchange membrane fuel cell (PEMFC) operated at $150^{\circ}C$ was evaluated by a controlling different amount of phosphoric acid (PA) to a membrane-electrode assembly (MEA) without humidification of the cells. The effects on MEA performance of the amount of PA in the cathode are investigated. The PA content in the cathodes was optimized for higher catalyst utilization. The highest value of the active electrochemical area is achieved with the optimum amount of PA in the cathode confirmed by in-situ cyclic voltammetry. The current density-voltage experiments (I-V curve) also shows a transient response of cell voltage affected by the amount of PA in the electrodes. Furthermore, this information was compared with the production variables such as hot pressing and vacuum drying to investigate those effect to the electrochemical performances.

• 대한화학회지
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• 제31권6호
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• pp.542-554
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• 1987

네자리 schiff base cobalt(II) 착물로서 Co(SED), Co(SND) and Co(SOPD)들을 합성하여 이들 착물들의 DMSO 용액에서 산소를 가하여 산소첨가 생성착물로 $[Co(SED)(DMSO)]_2O_2,\;[Co(SND)(DMSO)]_2O_2$ 및 $[Co(SOPD)(DMSO)]_2O_2$들을 합성하였다. 이들의 원소분석과 Cobalt정량, IR-Spectra, T.G.A. 및 자화율을 측정하여 산소:cobalt(II) 착물의 결합비가 1:2이고 네자리 schiff base cobalt(II)와 DMSO 및 산소가 6배위 결합으로 주어짐을 알았으며 Co(SED), Co(SND) 및 Co(SOPD) 착물들의 0.1M TEAP-DMSO용액에서 순환전압-전류법에 의한 산화 환원 과정이 Co(SED) 및 Co(SOPD)는 Co(II) / Co(III)와 Co(II) / Co(I) 과정이 가역적으로 일어나고 Co(SND)는 Co(II) / Co(III)과정은 가역적이지만 Co(II) / Co(I) 과정은 비가역적이다. 또한 산소 첨가 생성물의 착물들은 0.1M TEAP-DMSO 용액에서 산소결합의 환원과정이 $E_{pc}$ = -0.80~-0.89V에서 일어나고 이에 Couple인 산화과정은 $E_{pa}$ = -0.70~-0.76V에서 준가역적으로 일어남을 알았다.

• Journal of Electrochemical Science and Technology
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• 제9권4호
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• pp.282-291
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• 2018

The pristine fluorine-doped $SnO_2$ (abbreviated as FTO) inverse opal (IO) was developed using a 410 nm polystyrene bead template. The nanolayered copper tungsten oxide ($CuWO_4$) was decorated on the FTO IO film using a facile electrochemical deposition, subsequently followed by annealing at $500^{\circ}C$ for 90 min. The morphologies, crystalline structure, optical properties and photoelectrochemical characteristics of the FTO and $CuWO_4$-decorated FTO (briefly denoted as $FTO/CuWO_4$) IO film were investigated by field emission scanning electron microscopy, X-ray diffraction, UV-vis spectroscopy and electrochemical impedance spectroscopy, showing FTO IO in the hexagonally closed-pack arrangement with a pore diameter and wall thickness of about 300 nm and 20 nm, respectively. Above this film, the $CuWO_4$ was electrodeposited by controlling the cycling number in cyclic voltammetry, suggesting that the $CuWO_4$ formed during 4 cycles (abbreviated as $CuWO_4$(4 cycles)) on FTO IO film exhibited partial distribution of $CuWO_4$ nanoparticles. Additional distribution of $CuWO_4$ nanoparticles was observed in the case of $FTO/CuWO_4$(8 cycles) IO film. The $CuWO_4$ layer exhibits triclinic structure with an indirect band gap of approximately 2.5 eV and shows the enhanced visible light absorption. The photoelectrochemical (PEC) behavior was evaluated in the 0.5 M $Na_2SO_4$ solution under solar illumination, suggesting that the $FTO/CuWO_4$(4 cycles) IO films exhibit a photocurrent density ($J_{sc}$) of $0.42mA/cm^2$ at 1.23 V vs. reversible hydrogen electrode (RHE, denoted as $V_{RHE}$), while the FTO IO and $FTO/CuWO_4$(8 cycles) IO films exhibited a $J_{sc}$ of 0.14 and $0.24mA/cm^2$ at $1.23V_{RHE}$, respectively. This difference can be explained by the increased visible light absorption by the $CuWO_4$ layer and the favorable charge separation/transfer event in the cascading band alignment between FTO and $CuWO_4$ layer, enhancing the overall PEC performance.