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

Author: Wein O.  

Publisher: MAIK Nauka/Interperiodica

ISSN: 1023-1935

Source: Russian Journal of Electrochemistry, Vol.48, Iss.7, 2012-07, pp. : 704-711

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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.