Unusual voltammetry of the reduction of O2 in [C 4dmim][N(Tf)2] reveals a strong interaction of O 2*-with the [C4dmim]+ cation
Journal
Journal of Physical Chemistry C
Journal Volume
112
Journal Issue
35
Start Page
13709
End Page
13715
ISSN
19327455
Date Issued
2008
Author(s)
Barnes, Alexander S.
Rogers, Emma I.
Streeter, Ian
Hardacre, Christopher
Wildgoose, Gregory G.
Compton, Richard G.
Abstract
Voltammetric studies of the reduction of oxygen in the room temperature ionic liquid [C4dmim][N(Tf)2] have revealed a significant positive shift in the back peak potential, relative to that expected for a simple electron transfer. This shift is thought to be due to the strong association of the electrogenerated superoxide anion with the solvent cation. In this work we quantitatively simulate the microdisc electrode voltammetry using a model based upon a one-electron reduction followed by a reversible chemical step, involving the formation of the [C4dmim]+O 2*- ion-pair, and in doing so we extract a set of parameters completely describing the system. We have simulated the voltammetry in the absence of a following chemical step and have shown that it is impossible to simultaneously fit both the forward and reverse peaks. To further support the parameters extracted from fitting the experimental voltammetry, we have used these parameters to independently simulate the double step chronoamperometric response and found excellent agreement. The parameters used to describe the association of the O2*- with the [C 4dmim]+ were kf = 1.4 × 103 s-1 for the first-order rate constant and Keq = 25 for the equilibrium constant. © 2008 American Chemical Society.
SDGs
Type
journal article