• Title/Summary/Keyword: 환원전극

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Basic Studies on the Recovery of Zinc Metal from Wastewater by Cyclic Voltammetry (循環走査법에 의한 廢水로부터 亞鉛 回收에 관한 基礎 硏究)

  • 김진화;김동수
    • Resources Recycling
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    • v.10 no.3
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    • pp.29-36
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    • 2001
  • Cyclic voltammetry has been applied in the basic studies for the treatment and recovery of heavy metal component contained in wastewater by electrochemical reduction. The electrochemical behaviors of zinc ion for zinc metal electrode and carbon elec-trode were characterized by voltammograms and it was showed that zinc ions were reduced to metallic form below -0.76 V vs SHE. The change in the features of crystalline form of metallic zinc upon oxidation and reduction reaction was observed by X-ray diffraction method and the Am analysis verified that zinc ions were reduced to metal on copper plate. The results of this study were regarded to be important and meaningful in the treatment of heavy metal containing wastewater and, as a result, in the obtainment of metallic product by electrochemical method.

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Carbon Dioxide Reduction to Alcoholson Perovskite-Type $La_{0.9}$$Sr_{0.1}$$CuO_3$ Electrodes (페로브스카이트 ($La_{0.9}$$Sr_{0.1}$$CuO_3$) 전극에서 이산화탄소의 전해환원에 의한 알콜류 생성)

  • 김태근;임준혁
    • Journal of Environmental Science International
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    • v.5 no.5
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    • pp.677-682
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    • 1996
  • The electrochemical carbon dioxide reduction to produce acetaldehyde, methanol and ethanol is investigated by using perovskite type electrode ($La_{0.9}$$Sr_{0.1}$$CuO_3$). The experiments were Performed under 100 mA/cm2 and -2 to -2.5 V vs. Ag/AgCl. The highest faradaic efficiencies for methanol, ethanol, acetaldehyde were 11.6, 15.3, and 6.2%, respectively. The experimental data demonstrated that the capability of the perovskite type oxide for the electrode of electrochemical carbon dioxide reduction to produce alcohols was superior to other metal electrode. Key words : Perovskite, Electrode, Alcohol Formation, Electrochemical Reduction, Carbon Dioxide Fixation.

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Electrochemical Reduction for trans-Complexes of Cobalt (III) with Bis(ethylenediamine) and Monodendate Ligands (한자리 리간드를 포함하는 트란스비스 (에틸렌디아민) 코발트 (III) 이온의 전극 환원반응)

  • Jung-Ui Hwang;Jong-Jae Chung;Jae-Duck Lee
    • Journal of the Korean Chemical Society
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    • v.33 no.2
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    • pp.215-224
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    • 1989
  • Electrochemical reductions of $trans-[Co(en)_2X_2](ClO_4)_n$ (where X is cyanide, nitrite, ammonia, and isothiocyanate) were investigated by cyclic voltammetry and polarography at mercury and glassy carbon electrode. $trans-[Co(en)_2(CN)_2]ClO_4$ was reduced to Co(II) complex followed by adsorption to the mercury electrode. Cyanide ion was not released from the reduced Co(II) complex but the cyanide and (en) were released after the reduction to metallic cobalt. The other complexes except $trans-[Co(en)_2(CN)_2]ClO_4$ were reduced to cobalt(II) complexes followed by release of monodendate ligand, and (en) was released at the reduction step to metallic cobalt. $trans-[Co(en)_2(NO_2)_2]ClO_4$ was reduced to cobalt(Ⅱ) complex, and $NO_2^-$ ion was released followed by electroreduction through ECE mechanism at pH 2. On glassy carbon electrode, all complexes of Co(III) were reduced to Co(II) complexes with irreversible one-electron diffusion controlled reaction in which (en) was not released at this step. Increasing absorption wave number of complexes caused to negative shift of peak potential.

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The Effect of Electrode Spacing and Size on the Performance of Soil Microbial Fuel Cells (SMFC) (전극간 거리와 크기가 토양미생물연료전지의 성능에 미치는 영향)

  • Im, Seong-Won;Lee, Hye-Jeong;Chung, Jae-Woo;Ahn, Yong-Tae
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.11
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    • pp.758-763
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    • 2014
  • Soil microbial fuel cells (SMFC) have gained a great attention as an eco-friendly technology that can simultaneously generate electricity and treat organic pollutants from the contaminated soil. We evaluated the effect of electrode spacing and size on the performance of SMFC treating soil contaminated with organic pollutants. Maximum power density decreased with increase in electrode distance or decrease in electrode size, likely due to higher internal resistance. The maximum voltage and power density decreased from 326 mV and $19.5mW/m^2$ with 4 cm of electrode distance to 222 mV and $5.9mW/m^2$ with 9 cm of electrode distance. In case of electrode size test, the maximum voltage and power density generated was 291 mV, $0.34mW/m^3$ when both of anode and cathode area were $64cm^2$ with 4 cm of electrode distance. The maximum voltage decreased by 19~29% when the anode area decreased to $16cm^2$ while only 3~12% of voltage decreased with cathode area decrease. The maximum power density decreased by 49~68% with decreasing anode size, and by 29~47% with decreasing cathode size. These results showed that the anode area had more significant effects than the cathode area on the power generation of SMFC which has a high internal resistance due to a coexistence of soil and wastewater in the reactor.

Study of the Effect of Hydrazine Form and Titanium Electrode Condition on Reduction of Uranium(VI) n Nitric Acid (질산중의 우라늄(VI) 환원에 대한 하이드라이진 형태와 티타늄 전극상태의 영향연구)

  • Kim, K.W.;Lee, E.H.;Y.J. Shin;J.H. Yoo;Park, H.S.;Kim, Jong-Duk
    • Nuclear Engineering and Technology
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    • v.26 no.3
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    • pp.425-432
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    • 1994
  • Voltammogram analysis of U(VI) reduction at electrochemically non-pretreated/pretreated Ti electrodes in nitric acid and hydrazine($N_2$H$_4$)/protonated hydrazine($N_2$H$_{5}$$^{+}$) media was done in order to determine the effect of hydrazine form and Ti electrode condition on the reduction of U(VI) in nitric acid. In the case of non-pretreated Ti electrode, the reduction in nitric acid and hydrazine mono-hydrate solution needed a high activation overpotential and was affected by the ratio of hydrazine to nitric acid rather than by only absolute amount of hydrazine because of the decrease of solution conductivity and increase of iR drop, which were caused by proton consumption in the solution by the hydrazine. In the case of pretreated Ti electrode in nitric acid and protonated hydrazine solution, the reduction current peaks of U(VI) were clearer and higher enough to perform a kinetic analysis, compared with the case with the non-pretreated Ti electrode at the same potential, and the behavior was strongly affected by nitric acid. The presence of hydrazine was important in the reduction of U(VI) at the pretreated Ti electrode for preventing the reoxidation of U(IV), but the concentration of protonated hydrazine was not.t.

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Synthesis and Characteristic of Cu/YSZ Composite for High Temperature Electrolysis Cathode (고온수전해 수소극용 Cu/YSZ의 제조 및 특성)

  • Hong, Hyun-Seon;Kim, Jong-Min;Shin, Seock-Jae
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.11a
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    • pp.101-104
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    • 2007
  • 700 $^{\circ}C$이상의 온도에서 실시되는 고온수전해는 다가오는 수소경제시대의 주요한 수소제조기 술로 주목되고 있다. 이 연구에서는 Ni보다 전기전도도가 우수하고 가격이 저렴한 Cu를 사용하여 고온수 전해 수소극용 Cu/YSZ 복합체를 기계적합금법에 의해 제조하여 미세구조를 관찰하였고 Cu/YSZ를 수소전극으로 한 반전지를 제조하여 수조제조 실험을 실시하였다. Cu/YSZ 복합체는 Cu와 YSZ를 6:4(vol%)의 조성비로 유성밀을 사용하여 400 rpm으로 24시간 동안 실시하여 제조하였다. 고에너지 볼밀 후 500 nm이하의 나노크기의 복합체가 제조되었으며 Cu입자에 YSZ가 고르게 분포되어 있었다. 수은압입법으로 측정한 기공률은 70%이고 기공크기는 평균 0.5 ${\mu}m$으로 미세한 기공으로 이루어져 있었다. 제조된 Cu/YSZ 복합체를 수소전극으로 한 반전지를 제조하여 수소제조 실험을 실시한 결과 Ni/YSZ 전극보다 수소제조 성능이 우수한 것으로 나타났다. Cu의 높은 열팽창계수와 낮은 녹는점을 보완하면 우수한 고온수전해용 전극재료로 사용될 것으로 판단된다.

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Evaluation of Single and Stacked MFC Performances under Different Dissolved Oxygen Concentrations in Cathode Chamber (환원전극 DO 농도에 따른 단일 및 직렬연결 미생물연료전지 전기발생량 평가)

  • Yu, Jae-Cheul;Lee, Tae-Ho
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.4
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    • pp.249-255
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    • 2009
  • The performance of microbial fuel cell (MFC) can be affected by many factors including the rate of organic matter oxidation, the electron transfer to electrode by electrochemical bacteria, proton diffusion, the concentration of electron acceptor, the rate of electron acceptor reduction and internal resistance. the performance of MFC using oxygen as electron acceptor can be influenced by oxygen concentration as limit factors in cathode compartment. Many studies have been performed to enhance electricity production from MFC. The series or parallel stacked MFC connected several MFC units can use to increase voltages and currents produced from MFCs. In this study, a single MFC (S-MFC) and a stacked MFC (ST-MFC) using acetate as electron donor and oxygen as electron acceptor were used to investigate the influence of dissolved oxygen (DO) concentrations in cathode compartment on MFC performance. The power density (W/$m^3$) of S-MFC was in order DO 5 > 3 > 7 > 9 mg/L, the maximum power density (W/$m^3$) of S-MFC was 42 W/$m^3$ at DO 5 mg/L. The power density (W/$m^3$) of ST-MFC was in order DO 5 > 7 > 9 > 3 mg/L and the maximum power density (W/$m^3$) of STMFC was 20 W/$m^3$ at DO 5 mg/L. These results suggest that the DO concentration of cathode chamber should be considered as important limit factor of MFC operation and design for stacked MFC as well as single MFC. The results of ST-MFC operation showed the voltage decrease of some MFC units by salt formation on the surface of anode, resulting in decrease total voltage of ST-MFC. Therefore, connecting MFC units in parallel might be more appropriate way than series connections to enhance power production of stacked MFC.

Enhanced Electrochemical CO2 Reduction on Porous Au Electrodes with g-C3N4 Integration (g-C3N4 도입에 따른 다공성 Au 전극의 전기화학적 이산화탄소 환원 특성)

  • Jiwon Heo;Chaewon Seong;Jun-Seok Ha
    • Journal of the Microelectronics and Packaging Society
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    • v.31 no.2
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    • pp.78-84
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    • 2024
  • The electrochemical reduction of carbon dioxide (CO2) is gaining attention as an effective method for converting CO2 into high-value carbon compounds. This paper reports a facile meth od for synth esizing and characterizing g-C3N4-modified porous Au (pAu) electrodes for electrochemical CO2 reduction using e-beam deposition and anodization techniques. The fabricated pAu@g-C3N4 electrode (@ -0.9 VRHE) demonstrated superior electrochemical performance compared to the pAu electrode. Both electrodes exhibited a Faradaic efficiency (FE) of 100% for CO production. The pAu@g-C3N4 electrode achieved a maximum CO production rate of 9.94 mg/s, which is up to 2.2 times higher than that of the pAu electrode. This study provides an economical and sustainable approach to addressing climate change caused by CO2 emissions and significantly contributes to the development of electrodes for electrochemical CO2 reduction.

Influence of starch on the performance of dye-sensitized solar cells (염료감응 태양전지의 성능을 위한 녹말의 영향)

  • Jung, Youngsam;Bae, Joonsuk;Jeong, Woncher;Kim, Donghwan;Yoon, Sooyong;Kim, Seohyun
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.51-51
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    • 2011
  • 1991년 스위스연방기술원(EPFL) 화학과 교수 Michae Gratzel이 발명한 염료감응 태양전지 (DSSC)는 값싼 원료와 저가공비 면에서 가장 경쟁력 있는 기술의 하나로 큰 기대를 받고 있다. 염료감응 태양전지의 특징은 전극기판의 재료나 염료를 바꿈으로서 형상이나 색체에 다양성을 갖도록 할 수 있다. 일반적인 염료감응 태양전지의 원리는 태양광이 염료 분자에 흡수, 염료는 여기상태가 되어 전자를 n형 반도체인 $TiO_2$의 전도대로 흘리고, 전자는 TCO전극으로 이동하여 외부 부하에 전기 에너지를 전달하고 상대전극으로 이동, 염료는 $TiO_2$에 전달한 전자 수만큼 전해질로부터 전자를 공급 받아 원래의 상태로 돌아가게 되는 원리에 의하여 발전된다. 전해질로는 $I^-/I_3^-$와 같이 산화-환원 종으로 구성되어 있으며, $I^-$ 이온의 source로는 LiI, NaI,이미다졸리움 요오드 등이 사용되며, $I_3^-$는 이온은 $I_2$를 용매에 녹여 생성시킨다. 전해질 매질은 acetonitrile과 같은 액체 또는 PVdF와 같은 고분자가 사용될 수 있다. 액체형의 경우 산화-환원 이온 종이 매질 내에서 신속하게 움직여 염료의 재생을 원활하게 도와주기 때문에 높은 에너지 변환 효율이 가능하지만, 전극 간의 접합이 완벽하지 못할 경우 누액의 문제를 가지고 있다. 반면, 고분자를 매질로 채택할 경우에는 누액의 염료는 없지만 산화-환원 종의 움직임이 둔화되어 에너지 변환 효율에 나쁜 영향을 줄 수 있다. 따라서 고분자 전해질을 사용할 경우에는 산화-환원 이온 종이 매질 내에서 신속하게 전달 될 수 있도록 설계하는 것이 필요하다. 본 연구는 염료감응 태양전지에서 가장 큰 문제가 되고 있는 고체 전해질의 산화-환원 이온 종이 매질 내에서 신속하게 전달 될 수 있도록 dimethylsulfoxide solvent 에 녹말 일정량을 녹여 Starch-$I_2$ complex 를 시켜주므로, 광 전압{\cdot}{\cdot}$전가 증가되었으며, 전지의 안정성이 향상되었다.

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