On the theory of the galvanostatic relaxation technique as applied to redox electrodes with two consecutive charge-transfer steps

Abstract

Analysis of the galvanostatic single-pulse (GSP) method as applied to a redox electrode with two consecutive charge-transfer steps Red - e − → X and X - e − → Ox under conditions of non-stationary linear semi-infinite diffusion of the reagents Red and Ox and the intermediate X has been carried out. Relaxation equations for the linear region of the current density-overpotential relations and for exciting current pulses of step and quasi-trapezoidal form have been derived in analytical form. Methods of extracting kinetic data using these equations are discussed. Simple analytical approximations of the relaxation equations have been obtained for limiting cases. These approximations can be used for the classical graphical analysis of experimental data to determine the kinetic parameters of partial charge-transfer steps and diffusion coefficients of the reagents Red and Ox and the intermediate X. The GSP and impedance methods are compared.