Electrode currents and concentrations for transfer by diffusion and chemical reaction

Abstract

In the present paper we compute the time-dependent diffusion field around an electrode, which may be a plane or a sphere of constant radius, for an electrochemical system in which a single depolarizing species A through a rapid reversible electrode reaction gives rise to a transitory species B which is converted into a stable species C by a slow irreversible reaction solution. The mathematical solution method is such that by suitable choice of variables it is possible to solve the plane and sphere problems in one operation. The functions yielding concentrations and electrode currents are obtained as definite integrals which are evaluated numerically. By appropriate choice of weighting function the present results can be applied to the expanding sphere problem (dropping mercury electrode). The results are consistent with the spirit of the Ilkovic analysis. Numerical results for planar and spherical electrodes are presented in graphical form.