Potential Dependence of Electron-Transfer Rates at the Interface between Two Immiscible Electrolyte Solutions

Reduction of 7,7,8,8-Tetracyanoquinodimethane in 1,2-Dichloroethane by Aqueous Ferrocyanide Studied with Microelectrochemical Techniques

Jie Zhang, Patrick R. Unwin

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Abstract

Experimental studies of electron-transfer (ET) reactions at the interface between two immiscible electrolyte solutions (ITIES) were carried out with Fe(CN)6 4- as a reductant in water and 7,7,8,8-tetracyanoquinodimethane as an electron acceptor in 1,2-dichloroethane (DCE). The kinetics of this process have been determined using both scanning electrochemical microscopy and microelectrochemical measurements at expanding droplets. ClO4 - was employed in each phase to control the interfacial potential drop. The ET rate constants were found to depend on the interfacial potential drop, with an apparent ET coefficient in the range 0.30-0.41 with a moderate aqueous ionic strength 0.1-0.3 M and an electrolyte concentration in the DCE phase of 0.1 M. When the aqueous ionic strength was increased significantly to the levels employed in studies of externally polarized ITIES, the ET rate constant decreased appreciably and was less dependent on the interfacial potential drop. These latter studies yielded results comparable to those obtained at externally polarized ITIES.

Original languageEnglish
Pages (from-to)2341-2347
Number of pages7
JournalJournal of Physical Chemistry B
Volume104
Issue number10
Publication statusPublished - 16 Mar 2000
Externally publishedYes

Cite this

@article{27ce567c346846869e801e4d20a69323,
title = "Potential Dependence of Electron-Transfer Rates at the Interface between Two Immiscible Electrolyte Solutions: Reduction of 7,7,8,8-Tetracyanoquinodimethane in 1,2-Dichloroethane by Aqueous Ferrocyanide Studied with Microelectrochemical Techniques",
abstract = "Experimental studies of electron-transfer (ET) reactions at the interface between two immiscible electrolyte solutions (ITIES) were carried out with Fe(CN)6 4- as a reductant in water and 7,7,8,8-tetracyanoquinodimethane as an electron acceptor in 1,2-dichloroethane (DCE). The kinetics of this process have been determined using both scanning electrochemical microscopy and microelectrochemical measurements at expanding droplets. ClO4 - was employed in each phase to control the interfacial potential drop. The ET rate constants were found to depend on the interfacial potential drop, with an apparent ET coefficient in the range 0.30-0.41 with a moderate aqueous ionic strength 0.1-0.3 M and an electrolyte concentration in the DCE phase of 0.1 M. When the aqueous ionic strength was increased significantly to the levels employed in studies of externally polarized ITIES, the ET rate constant decreased appreciably and was less dependent on the interfacial potential drop. These latter studies yielded results comparable to those obtained at externally polarized ITIES.",
author = "Jie Zhang and Unwin, {Patrick R.}",
year = "2000",
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language = "English",
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journal = "Journal of Physical Chemistry B",
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publisher = "American Chemical Society",
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TY - JOUR

T1 - Potential Dependence of Electron-Transfer Rates at the Interface between Two Immiscible Electrolyte Solutions

T2 - Reduction of 7,7,8,8-Tetracyanoquinodimethane in 1,2-Dichloroethane by Aqueous Ferrocyanide Studied with Microelectrochemical Techniques

AU - Zhang, Jie

AU - Unwin, Patrick R.

PY - 2000/3/16

Y1 - 2000/3/16

N2 - Experimental studies of electron-transfer (ET) reactions at the interface between two immiscible electrolyte solutions (ITIES) were carried out with Fe(CN)6 4- as a reductant in water and 7,7,8,8-tetracyanoquinodimethane as an electron acceptor in 1,2-dichloroethane (DCE). The kinetics of this process have been determined using both scanning electrochemical microscopy and microelectrochemical measurements at expanding droplets. ClO4 - was employed in each phase to control the interfacial potential drop. The ET rate constants were found to depend on the interfacial potential drop, with an apparent ET coefficient in the range 0.30-0.41 with a moderate aqueous ionic strength 0.1-0.3 M and an electrolyte concentration in the DCE phase of 0.1 M. When the aqueous ionic strength was increased significantly to the levels employed in studies of externally polarized ITIES, the ET rate constant decreased appreciably and was less dependent on the interfacial potential drop. These latter studies yielded results comparable to those obtained at externally polarized ITIES.

AB - Experimental studies of electron-transfer (ET) reactions at the interface between two immiscible electrolyte solutions (ITIES) were carried out with Fe(CN)6 4- as a reductant in water and 7,7,8,8-tetracyanoquinodimethane as an electron acceptor in 1,2-dichloroethane (DCE). The kinetics of this process have been determined using both scanning electrochemical microscopy and microelectrochemical measurements at expanding droplets. ClO4 - was employed in each phase to control the interfacial potential drop. The ET rate constants were found to depend on the interfacial potential drop, with an apparent ET coefficient in the range 0.30-0.41 with a moderate aqueous ionic strength 0.1-0.3 M and an electrolyte concentration in the DCE phase of 0.1 M. When the aqueous ionic strength was increased significantly to the levels employed in studies of externally polarized ITIES, the ET rate constant decreased appreciably and was less dependent on the interfacial potential drop. These latter studies yielded results comparable to those obtained at externally polarized ITIES.

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M3 - Article

VL - 104

SP - 2341

EP - 2347

JO - Journal of Physical Chemistry B

JF - Journal of Physical Chemistry B

SN - 1520-6106

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ER -