• Title/Summary/Keyword: Electron transfer reaction

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Computational Modeling of Cyclic Voltammetry on Multi-electron Electrode Reaction using Diffusion Model (확산모델을 이용한 다중전자 전극반응에 대한 순환전위법의 전산모델링)

  • Cho, Ha-Na;Yoon, Do-Young
    • Journal of the Korean Electrochemical Society
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    • v.15 no.3
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    • pp.165-171
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    • 2012
  • Here is implemented MATLAB program to analyze the characteristic curves of cyclic voltammetry which involves the multi-electron electrode reaction considered as key processes in electrochemical systems. For the electrochemical mass-transfer system, Fick's concentration equation subject to semi-infinite diffusion model for the boundary condition was discretized and solved by the explicit finite difference method. The resulting concentration values were converted into currents at each node by using Butler-Volmer equation. Based on the good agreement between the present numerical solution and the existing experimental results, effects of kinetic constants and CV scan rates on the reaction mechanism in multi-electron transfer processes were investigated effectively.

Redox Property of Self-Assembled Viologen Monolayers with Various Concentration using QCM (수정진동자를 이용한 Viologen 자기조립 단분자막의 농도변화에 의한 전하이동 특성 연구)

  • Park, Sang-Hyun;Lee, Dong-Yun;Kang, Hye-Young;Park, Jae-Chul;Kwon, Young-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.05a
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    • pp.63-64
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    • 2006
  • 본 연구에서는 광에너지를 화학적인 에너지로 변환할 때, 디바이스의 전하전달 매개를 위한 electron transfer mediator로서 널리 이용되는 Viologen이 자기조립화된 수정진동자률 전기화학법의 하나인 순환전압전류법(Cyclic Voltammetry)을 이용하여 산화 환원 반응 (redox reaction) 특성과 주사속도와 피크전류와의 상관관계를 분석하였다. 먼저 수정진동자를 친수 처리한 후, 메탄올 용액과 아세토니트릴 용액을 섞은 용매에 Viologen 분자를 자기조립 (self-assembly)하여, 전해질 용액의 농도 변화에 따른 산화 환원반응 특성과 피크전류의 값을 측정하였다 주사 속도를 2 배씩 증가하여 피크전류와의 상관관계를 조사한 결과, 선형적인 증가를 보였으며, 이를 통해 가역적인 반응(reversible reaction)이 일어났음을 확인할 수 있었다. 또한, 산화 환원 반응과 동시에 측정된 수정진동자의 공진 주파수(resonant frequency) 변화로부터 전하이동(charge transfer) 특성에 의해 반응에 참가한 이온의 질량을 알 수 있었다.

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Reaction of $FeC_5H_5^+$ Ion with Neutral Ferrocene: The Dependence of Reaction Pathways on Its Internal Energy

  • 김병주;소훈영
    • Bulletin of the Korean Chemical Society
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    • v.20 no.10
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    • pp.1181-1185
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    • 1999
  • The reaction of FeC5H5+ ion with ferrocene molecule is investigated using FT-ICR mass spectrometry. FeC5H5+ ions are generated by dissociative ionization of ferrocenes using an electron beam. The reaction gives rise to the formation of the adduct ion, Fe2(C5H5)3+, in competition with charge transfer reaction leading to the formation of ferrocene molecular ion, Fe(C5H5)2+·. The branching ratio of the adduct ion increases as the internal energy of the reactant ion decreases and correspondingly the branching ratio for the charge transfer reaction product decreases. The observed rate of the addition reaction channel is slower than that of the charge transfer reaction. The observation of the stable adduct ions in the low-pressure ICR cell is attributed to the radiative cooling of the activated ion-molecule complex. The mechanism of the reaction is presented to account for the observed experimental results.

Resolution of a Multi-Step Electron Transfer Reaction by Time Resolved Impedance Measurements: Sulfur Reduction in Nonaqueous Media

  • Park, Jin-Bum;Chang, Byoung-Yong;Yoo, Jung-Suk;Hong, Sung-Young;Park, Su-Moon
    • Bulletin of the Korean Chemical Society
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    • v.28 no.9
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    • pp.1523-1530
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    • 2007
  • The first reduction peak of the cyclic voltammogram (CV) for sulfur reduction in dimethyl sulfoxide has been studied using time resolved Fourier transform electrochemical impedance spectroscopic (FTEIS) analysis of small potential step chronoamperometric currents. The FTEIS analysis results reveal that the impedance signals obtained during short potential steps can be resolved into electron transfer reactions of two different time constants in a high frequency region. The FTEIS method provides snap shots of impedance profiles during an earlier phase of the reaction, leading to time resolved EIS measurements. Our results obtained by the FTEIS analysis are consistent with a series of electron transfer and chemical equilibrium steps of a complex reaction, making up an ECE (electrochemical-chemical-electrochemical) mechanism postulated from the results of computer simulation.

Counter Ion Effect on Photoinduced Electron Transfer Reaction between Ruthenium Complexes

  • Sonoyama, Noriyuki;Kaizu, Youkoh
    • Analytical Science and Technology
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    • v.8 no.4
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    • pp.481-486
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    • 1995
  • Quenching experiments by photoinduced electron transfer between a charged donor and a neutral acceptor were carried out in acetonitrile, dichloromethane and mixed solvents of acetonitrile and dichloromethane. Tris(2, 2'-bipyridine) ruthenium(II) ($[Ru(bpy)_3]^{2+}$) which has 2+ charge and dicyanobis (2, 2'-bipyridine) ruthenium(II) ($Ru(bpy)_2(CN)_2$) which has no charge were used as electron donors, and a series of tris(${\beta}$-diketonato) ruthenium (III) was used as acceptor. In dichloromethane, $[Ru(bpy)_3]^{2+}$ and its counter ions ($ClO{_4}^-$) form ion pair. In the estimate of ${\Delta}G$ of electron transfer, the electrostatic potential between counter ions and product ion pair produced by electron transfer must be taken into account. A similar effect of counter ions was found in mixed solvents of 10, 30, 50, 70 and 90% acetonitrile ratio in volume. The effect of counter ion on ${\Delta}G$ became smaller with the increase in acetonitrile ratio. The result in mixed solvents suggests that $[Ru(bpy)_3]^{2+}$ and its counter ions form ion pair even in 90% acetonitrile solution.

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Light-Induced Electron Transfer Reactions in FeⅡ-CoⅢ Binuclear Complexes ($Fe^{II}-Co^{III}$이핵착물의 광유발 전자이동반응)

  • Lee, Gyu Hwan
    • Journal of the Korean Chemical Society
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    • v.38 no.8
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    • pp.598-602
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    • 1994
  • Light-induced electron transfer reaction within binuclear complex $(NC)_5FeII-L-CoIII(NH_3)_5$ was studied with steady-state photolysis and the rate constants were measured for various bridging lignands. klight and quantum yields for BP, PHEN, DAP having conjugation between metal binding sites were about $3{\times}10^{-2} sec^{-1}$ and 1, and for BPEA having no conjugation were about $2{\times}10^{-4} sec^{-1}$ and 0.03. Light-induced electron transfer reaction within binuclear complex was proved to be the chemical mechanism which had charge transfer excited state MLCT*.

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Reactivity and Reaction Mechanism for Reactions of 1, 1'-(Azodicarbonyl) dipiperidine with Triphenylphosphines

  • 성대동;최미정;하근문;엄태섭
    • Bulletin of the Korean Chemical Society
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    • v.20 no.8
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    • pp.935-938
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    • 1999
  • Reactivity and reaction mechanism for the reactions of 1,1'-(azodicarbonyl) dipiperidine with triphenylphosphines are investigated using kinetic method. The cation radical, Ph3P and the anion radical, -N-N - are produced during the course of the reaction. The cation radical is formed by the transfer of an electron from phosphorus to the nitrogen atom. The anion radical is formed by the addition of the one electron to the azo rad-ical. The rate constants are decreased by electron withdrawing groups while they are increased by electron donating groups present in triphenylphosphine. The electron density increases on nitrogen, while positive charge is developed on phosphorus in the transition state.

Selection of Mediators for Bioelectrochemical Nitrate Reduction

  • Kim Seung Hwan;Song Seung Hoon;Yoo Young Je
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.10 no.1
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    • pp.47-51
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    • 2005
  • The bioelectrochemical reduction of nitrate in the presence of various mediators including methyl viologen and azure A was studied using a 3-electrode voltammetric system. The catalytic potential for the reduction of the mediators was observed in the reactor, which for methyl viologen and azure A were -0.74 V and -0.32 V, respectively, with respect to the potential of Ag/AgCl reference electrode. This potential was then applied to a working electrode to reduce each mediator for enzymatic nitrate reduction. Nitrite, the product of the reaction, was measured to observe the enzymatic nitrate reduction in the reaction media. Methyl viologen was observed as the most efficient mediator among those tested, while azure A showed the highest electron efficiency at the intrinsic reduction potential when the mediated enzyme reactions were carried out with the freely solubilized mediator. The electron transfer of azure A with respect to time was due to the adhesion of azure A to the hydrophilic surface during the reduction. In addition, the use of the adsorbed mediator on conductive activated carbon was proposed to inhibit the change in the electron transfer rate during the reaction by maintaining a constant mediator concentration and active surface area of the electrode. Azure A showed better than nitrite formation than methyl viologen when used with activated carbon.

PHOTOINDUCED ELECTRON TRANSFER REACTIONS OF 1,4-DIPHENYL-1,3-BUTADIYNE

  • Kim, Bang-Duk;Shim, Sang-Chul
    • Journal of Photoscience
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    • v.5 no.1
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    • pp.23-26
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    • 1998
  • Irradiation of diphenylbutadiyne (DPB) in methanol with 9,10-dicyanoanthracene (DCA) yields four methanol adducts, two more than the products obtained in the absence of DCA. Laser flash photolysis studies indicate the reaction to proceed through a photoinduced electron transfer mechanism involving DPB cation radical and DCA anion radical.

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