Electrolyte cation dependence of the electron transfer kinetics associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in propylene carbonate

Jiezhen Li, Cameron L. Bentley, Tadaharu Ueda, Alan M. Bond, Jie Zhang

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Changing the supporting electrolyte cation from tetrabutylammonium to 1-butyl-3-methylimidazolium is known to significantly increase the apparent heterogeneous electron transfer rate constants (k 0 value at the formal reversible potential, (E F 0)) associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in aprotic organic media. In this study, supporting electrolytes containing 7 different cations, namely 1-ethyl-3-methylimidazolium ([EMIM]+), 1-butyl-3-methylimidazolium ([BMIM]+), 1-butyl-1-methylpyrrolidinium ([Py14]+), tetraethylammonium ([TEA]+), tetrapropylammonium ([TPA]+), tetrabutylammonium ([TBA]+) and tetrahexylammonium ([THA]+), have been investigated in order to provide a systematic account of the influence of the electrolyte cations on the rate of polyoxometalate (POM) electron transfer at a platinum disk electrode. Fourier transformed alternating current (FTAC) voltammetry has been used for the measurement of fast kinetics and DC cyclic voltammetry for slow processes. The new data reveal the formal reversible potentials and electron-transfer rate constants associated with the VV/IV (k V 0) and WVI/V (k W 0) processes correlate with the size of the supporting electrolyte cation. k V 0 and k W 0 values decrease in the order, [EMIM]+ >[BMIM]+ >[Py14]+ ≈[TEA]+ >[TPA]+ >[TBA]+ >[THA]+ for both processes. However, while k V 0 decreases gently with increasing cation size (k 0 =0.1 and 0.002cms-1 with [EMIM]+ and [THA]+ electrolyte cations, respectively), the decrease in k W 0 is much more drastic (k 0 =0.1 and 2×10-6 cms-1 for [EMIM]+ and [THA]+, respectively). Possible explanations for the observed trends are discussed (e.g., ion-pairing, viscosity, adsorption and the double-layer effect), with inhibition of electron-transfer by a blocking "film" of electrolyte cations considered likely to be the dominant factor, supported by a linear plot of ln(k 0) vs. ln(d) (where d is the estimated thickness of the adsorbed layer on the electrode surface) for both the VV/IV and WVI/V processes.

Original languageEnglish
Pages (from-to)193-201
Number of pages9
JournalJournal of Electroanalytical Chemistry
Volume819
DOIs
Publication statusPublished - 15 Jun 2018

Keywords

  • Cation dependence
  • Electron transfer kinetics
  • Fourier transformed ac voltammetry
  • Polyoxometalates
  • Propylene carbonate

Cite this

@article{7681d869e383461180c65088f4bf7579,
title = "Electrolyte cation dependence of the electron transfer kinetics associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in propylene carbonate",
abstract = "Changing the supporting electrolyte cation from tetrabutylammonium to 1-butyl-3-methylimidazolium is known to significantly increase the apparent heterogeneous electron transfer rate constants (k 0 value at the formal reversible potential, (E F 0)) associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in aprotic organic media. In this study, supporting electrolytes containing 7 different cations, namely 1-ethyl-3-methylimidazolium ([EMIM]+), 1-butyl-3-methylimidazolium ([BMIM]+), 1-butyl-1-methylpyrrolidinium ([Py14]+), tetraethylammonium ([TEA]+), tetrapropylammonium ([TPA]+), tetrabutylammonium ([TBA]+) and tetrahexylammonium ([THA]+), have been investigated in order to provide a systematic account of the influence of the electrolyte cations on the rate of polyoxometalate (POM) electron transfer at a platinum disk electrode. Fourier transformed alternating current (FTAC) voltammetry has been used for the measurement of fast kinetics and DC cyclic voltammetry for slow processes. The new data reveal the formal reversible potentials and electron-transfer rate constants associated with the VV/IV (k V 0) and WVI/V (k W 0) processes correlate with the size of the supporting electrolyte cation. k V 0 and k W 0 values decrease in the order, [EMIM]+ >[BMIM]+ >[Py14]+ ≈[TEA]+ >[TPA]+ >[TBA]+ >[THA]+ for both processes. However, while k V 0 decreases gently with increasing cation size (k 0 =0.1 and 0.002cms-1 with [EMIM]+ and [THA]+ electrolyte cations, respectively), the decrease in k W 0 is much more drastic (k 0 =0.1 and 2×10-6 cms-1 for [EMIM]+ and [THA]+, respectively). Possible explanations for the observed trends are discussed (e.g., ion-pairing, viscosity, adsorption and the double-layer effect), with inhibition of electron-transfer by a blocking {"}film{"} of electrolyte cations considered likely to be the dominant factor, supported by a linear plot of ln(k 0) vs. ln(d) (where d is the estimated thickness of the adsorbed layer on the electrode surface) for both the VV/IV and WVI/V processes.",
keywords = "Cation dependence, Electron transfer kinetics, Fourier transformed ac voltammetry, Polyoxometalates, Propylene carbonate",
author = "Jiezhen Li and Bentley, {Cameron L.} and Tadaharu Ueda and Bond, {Alan M.} and Jie Zhang",
year = "2018",
month = "6",
day = "15",
doi = "10.1016/j.jelechem.2017.10.028",
language = "English",
volume = "819",
pages = "193--201",
journal = "Journal of Electroanalytical Chemistry",
issn = "1572-6657",
publisher = "Elsevier",

}

Electrolyte cation dependence of the electron transfer kinetics associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in propylene carbonate. / Li, Jiezhen; Bentley, Cameron L.; Ueda, Tadaharu; Bond, Alan M.; Zhang, Jie.

In: Journal of Electroanalytical Chemistry, Vol. 819, 15.06.2018, p. 193-201.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Electrolyte cation dependence of the electron transfer kinetics associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in propylene carbonate

AU - Li, Jiezhen

AU - Bentley, Cameron L.

AU - Ueda, Tadaharu

AU - Bond, Alan M.

AU - Zhang, Jie

PY - 2018/6/15

Y1 - 2018/6/15

N2 - Changing the supporting electrolyte cation from tetrabutylammonium to 1-butyl-3-methylimidazolium is known to significantly increase the apparent heterogeneous electron transfer rate constants (k 0 value at the formal reversible potential, (E F 0)) associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in aprotic organic media. In this study, supporting electrolytes containing 7 different cations, namely 1-ethyl-3-methylimidazolium ([EMIM]+), 1-butyl-3-methylimidazolium ([BMIM]+), 1-butyl-1-methylpyrrolidinium ([Py14]+), tetraethylammonium ([TEA]+), tetrapropylammonium ([TPA]+), tetrabutylammonium ([TBA]+) and tetrahexylammonium ([THA]+), have been investigated in order to provide a systematic account of the influence of the electrolyte cations on the rate of polyoxometalate (POM) electron transfer at a platinum disk electrode. Fourier transformed alternating current (FTAC) voltammetry has been used for the measurement of fast kinetics and DC cyclic voltammetry for slow processes. The new data reveal the formal reversible potentials and electron-transfer rate constants associated with the VV/IV (k V 0) and WVI/V (k W 0) processes correlate with the size of the supporting electrolyte cation. k V 0 and k W 0 values decrease in the order, [EMIM]+ >[BMIM]+ >[Py14]+ ≈[TEA]+ >[TPA]+ >[TBA]+ >[THA]+ for both processes. However, while k V 0 decreases gently with increasing cation size (k 0 =0.1 and 0.002cms-1 with [EMIM]+ and [THA]+ electrolyte cations, respectively), the decrease in k W 0 is much more drastic (k 0 =0.1 and 2×10-6 cms-1 for [EMIM]+ and [THA]+, respectively). Possible explanations for the observed trends are discussed (e.g., ion-pairing, viscosity, adsorption and the double-layer effect), with inhibition of electron-transfer by a blocking "film" of electrolyte cations considered likely to be the dominant factor, supported by a linear plot of ln(k 0) vs. ln(d) (where d is the estimated thickness of the adsorbed layer on the electrode surface) for both the VV/IV and WVI/V processes.

AB - Changing the supporting electrolyte cation from tetrabutylammonium to 1-butyl-3-methylimidazolium is known to significantly increase the apparent heterogeneous electron transfer rate constants (k 0 value at the formal reversible potential, (E F 0)) associated with the [SVW11O40]3-/4- (VV/IV) and [SVW11O40]4-/5- (WVI/V) processes in aprotic organic media. In this study, supporting electrolytes containing 7 different cations, namely 1-ethyl-3-methylimidazolium ([EMIM]+), 1-butyl-3-methylimidazolium ([BMIM]+), 1-butyl-1-methylpyrrolidinium ([Py14]+), tetraethylammonium ([TEA]+), tetrapropylammonium ([TPA]+), tetrabutylammonium ([TBA]+) and tetrahexylammonium ([THA]+), have been investigated in order to provide a systematic account of the influence of the electrolyte cations on the rate of polyoxometalate (POM) electron transfer at a platinum disk electrode. Fourier transformed alternating current (FTAC) voltammetry has been used for the measurement of fast kinetics and DC cyclic voltammetry for slow processes. The new data reveal the formal reversible potentials and electron-transfer rate constants associated with the VV/IV (k V 0) and WVI/V (k W 0) processes correlate with the size of the supporting electrolyte cation. k V 0 and k W 0 values decrease in the order, [EMIM]+ >[BMIM]+ >[Py14]+ ≈[TEA]+ >[TPA]+ >[TBA]+ >[THA]+ for both processes. However, while k V 0 decreases gently with increasing cation size (k 0 =0.1 and 0.002cms-1 with [EMIM]+ and [THA]+ electrolyte cations, respectively), the decrease in k W 0 is much more drastic (k 0 =0.1 and 2×10-6 cms-1 for [EMIM]+ and [THA]+, respectively). Possible explanations for the observed trends are discussed (e.g., ion-pairing, viscosity, adsorption and the double-layer effect), with inhibition of electron-transfer by a blocking "film" of electrolyte cations considered likely to be the dominant factor, supported by a linear plot of ln(k 0) vs. ln(d) (where d is the estimated thickness of the adsorbed layer on the electrode surface) for both the VV/IV and WVI/V processes.

KW - Cation dependence

KW - Electron transfer kinetics

KW - Fourier transformed ac voltammetry

KW - Polyoxometalates

KW - Propylene carbonate

UR - http://www.scopus.com/inward/record.url?scp=85032390805&partnerID=8YFLogxK

U2 - 10.1016/j.jelechem.2017.10.028

DO - 10.1016/j.jelechem.2017.10.028

M3 - Article

VL - 819

SP - 193

EP - 201

JO - Journal of Electroanalytical Chemistry

JF - Journal of Electroanalytical Chemistry

SN - 1572-6657

ER -