Charge Transfer Kinetics in Thin-Film Voltammetry. Theoretical Study under Conditions of Square-Wave Voltammetry

Abstract

An electrode reaction controlled by charge transfer kinetics and occurring in a finite diffusion space is theoretically studied under conditions of square-wave voltammetry (SWV). A simple numerical solution is derived based on the modified step-function method (Mirceski, V. J. Electroanal. Chem. 2003, 545, 29). The SW voltammetric response is mainly controlled by the thickness parameter Λ = L , the redox kinetic parameter K = ks / , and the electron transfer coefficient α, where L is the thickness of the film, ks is the heterogeneous standard redox rate constant, f is the frequency of the potential modulation, and D is the diffusion coefficient of the electroactive species. The mass transport regime is predominantly determined by the thickness parameter. The typical interval for finite diffusion is log(Λ) ≤ 0.3. The main properties of the electrode reaction occurring in a finite diffusion space are the quasireversible maximum and the splitting of the net SW peak. The quasireversible maximum is manifested ...