  The voltammetry for the reduction of oxygen at a microdisc electrode is
reported in two room temperature ionic liquids: 1-butyl-1-methylpyyrolidinium
bis(trifluoromethylsulfonyl) imide ([Bmpyrr][NTf2]) and
trihexyltetradecylphosphonium bis9trifluoromethylsulfonyl) imide
([P14,6,6,6][NTf2]) at 298 K. Simulated voltammograms using Butler-Volmer
theory and Symmetric Marcus-Hush (SMH) theory were compared with experimental
data. Butler-Volmer theory consistently provided experimental parameters with a
higher level of certainty than SMH theory. A value of solvent reorganisation
energy for oxygen reduction in ionic liquids was inferred for the first time as
0.4-0.5 eV, which is attributable to inner-sphere reorganisation with a
negligible contribution from solvent reorganisation. The developed
Butler-Volmer and Symmetric Marcus-Hush programs are also used to theoretically
study the possibility of kinetically limited steady state currents, and to
establish an approximate equivalence relationship between microdisc electrodes
and spherical electrodes resting on a surface for steady state voltammetry for
both Butler-Volmer and Symmetric Marcus-Hush theory.
