Potential-sweep voltammetry: General theory of chemical polarization

Abstract

A general theoretical approach is presented for the calculation of single potential-sweep voltammetric curves in such conditions that a chemical reaction of any order, preceding, following or parallel to the charge transfer, kinetically influences the over-all electrode process. For limiting values of the adimensional parameters defining the interaction between chemical reaction and diffusion kinetics, polarization curves present characteristic behaviour, corresponding to pure kinetic or diffusion conditions. Some general diagnostic criteria are derived, allowing information on the rate-determining step of a complex electrode reaction to be acquired, by analysing the shape of the voltammetric curves and the variations of their characteristic current and potential values as a function of experimental parameters.The possibilities of evaluating rate and/or equilibrium constants of chemical reactions of any order coupled with the electron-transfer process are discussed.