Application of Asymmetric Marcus-Hush Theory to Voltammetry in Room-Temperature Ionic Liquids

Eden E. L. Tanner, Edward O. Barnes, Caitlin B. Tickell, Peter Goodrich, Christopher Hardacre, Richard G. Compton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Asymmetric MarcusHush (AMH) theory is applied for the first time in ionic solvents to model the voltammetric reduction of oxygen in 1-butyl-1-methylpyrrolidinium bis-(trifluoromethylsulfonyl)-imide and of 2-nitrotoluene (2-NT), nitrocyclopentane (NCP), and 1-nitro-butane (BuN) in trihexyltetradecylphosphonium tris(pentafluoroethyl)trifluorophosphate on a gold microdisc electrode. An asymmetry parameter, gamma, was estimated for all systems as -0.4 for the reduction of oxygen and -0.05, 0.25, and 0 +/- 0.05 for the reductions of 2-NT, NCP, and BuN, respectively, which suggests equal force constants of reactants and products in the case of 2-NT and BuN and unequal force constants for oxygen and NCP where the force constants of the oxidized species are greater than the reduced species in the case of oxygen and less than the reduced species in the case of NCP. Previously measured values for a, the Butler-Volmer transfer coefficient, reflect this in each case. Where appreciable asymmetry occurs, AMH theory was seen to parametrize the experimental data better than either Butler-Volmer or symmetric Marcus-Hush theory, allowing additionally the extraction of reorganization energy. This is the first study to provide key physical insights into electrochemical systems in room-temperature ionic liquids using AMH theory, allowing elucidation of the reorganization energies and the relative force constants of the reactants and products in each reaction.

Original languageEnglish
Pages (from-to)7360-7370
Number of pages11
JournalJournal of Physical Chemistry C
Volume119
Issue number13
Early online date16 Mar 2015
DOIs
Publication statusPublished - 2015

Keywords

  • EXPONENTIALLY EXPANDING MESH
  • BUTLER-VOLMER DESCRIPTIONS
  • ONE-ELECTRON OXIDATION
  • MICRODISK ELECTRODES
  • EFFICIENT SIMULATION
  • DIFFUSION-PROCESSES
  • OXYGEN REDUCTION
  • MERCURY MICROELECTRODES
  • ELECTRIFIED INTERFACES
  • CYCLIC VOLTAMMETRY.

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