Convolution potential sweep voltammetry V. Determination of charge transfer kinetics deviating from the Butler-Volmer behaviour

Abstract

Convolution potential sweep voltammetry is applied to the analysis of charge transfer kinetics. The possibility of using the method without assuming a priori the validity of a given kinetic law, e.g. the Butler-Volmer law as usually done, is illustrated on the example of the reduction of tert-nitrobutane in acetonitrile and dimethylformamide. It is found that the post-factum experimental kinetics indeed deviate significantly from the Butler-Volmer behavior, involving a dependence of the transfer coefficient α upon the electrode potential. It is shown that the experimental variations of α match the orders of magnitude predicted by the Marcus theory. A procedure is proposed and applied for determining the reversible half-wave potential for redox couples in which one species is not quite stable chemically by combining the cyclic voltammetry and CPSV data.