Estimate of mass-transfer rate via Nernst model with Ohmic losses

Abstract

The limiting current technique, employed e.g. in electrodiffusion flow diagnostics, is based on an oversimplified electrochemical concept, which accounts only for the convective transport of depolarizers across a diffusion layer with constant bulk and wall concentrations. However, there are additional transport resistances that cannot be neglected: Faradaic resistance at surface of working electrode, and Ohmic losses in the bulk of electrolyte solution. Effect of these additional resistances is analyzed using the Nernst model of a two electrode cell (no reference electrode). The Faradaic resistances due to electrode kinetics are considered for a single redox couple O + ne = R according to the Butler Volmer electrode kinetics. The effect of Ohmic losses is accounted for, considering primary current distribution for a uniformly accessible circular electrode.