Straightforward determination of homogeneous kinetics using Fourier transform alternating current voltammetry (FTACV)

Abstract

This work describes a novel method by which the homogeneous kinetics for an ErevCirrev system can be deduced using only the forward scan of second harmonic FTACV. We show that ratio of the heights of the two lobes of the 2nd harmonic voltammograms readily provides this information by fitting data to a working curve modelled by the simple equation ilobe,right/ilobe,left=1/(1+kτs), where τs is the characteristic voltammetric timescale. The validity of the relationship was tested by comparison with both simulated and experimental data. This novel approach offers the advantage of quick and easy determination of kf, while increasing accuracy by omitting the ambiguity in determining a baseline and minimising the effects of electrode passivation. We also show that these changes can be explained by considering the change in surface concentration of the [Ox] and [Red] species over the course of a scan, which are more profoundly expressed in the FTACV response compared with CV.