A numerical modelling of voltammetric reduction of substituted iodobenzenes reaction series. A relationship between reductions in the consecutive-mode multistep system and a multicomponent system. Determination of the potential variation of the elementary charge transfer coefficient

The cyclic voltammetry simulation of a competition between stepwise and concerted dissociative electron transfer, the modeling of alpha apparent variability, the relationship between apparent and elementary kinetic parameters

A comparison of elementary (input) and apparent (output) values of the transfer coefficient was carried out for simulated kinetic cyclic voltammetry spectrum from stepwise to concerted mechanism. The resulting patterns of alphaapp versus Ep plots do not provide sufficient information to discriminate between the two mechanisms. It has been demonstrated that non-linear alphaapp patterns are characteristic for the pure stepwise mechanism obeying the Butler-Volmer kinetics. The change in alphaapp is not a sufficient condition for the transition from stepwise to concerted mechanism. This paper contains visualizations of the relationship between the apparent and elementary transfer coefficient. The difference between the potential variabilities of alphaapp and alphaelem (a frequent source of confusion) is also discussed.

A comparison of the multistep consecutive reduction mode with the multicomponent system reduction mode in cyclic voltammetry

The multistep consecutive ECE-ECE reduction process A(e)-->B(k(f2))-->C(e)-->D(e)-->E(k(f2))-->F(e)-->G has been compared with reduction in multicomponent system A(e)-->B, C(e)-->D, D(e)-->E, F(e)-->G. A simple method of transformation has been devised to disclose the subtle structure of the complex cyclic voltammetry (CV) responses and illustrated by the ECE-ECE process modeled earlier. The method can be applied to any multi-electron CV experimental curve for which a numerical modeling has been done. Electroreduction processes similar to those considered here are often met in practice. An attempt of unification of consecutive electroreduction and electroreduction of multicomponent system has been made. Interrelation between research and analytical voltammetry aspects of the problem is also discussed.