Steady‐State Polarization at Porous, Flow‐Through Electrodes with Small Pore Diameter: I . Reversible Kinetics

Abstract

This paper considers the effect of mass transfer and ohmic limitations on the current‐polarization relations for porous flow‐through electrodes with fine pores, for reversible one‐electron transfer reactions. The model includes mass transfer by both axial forced convection and axial diffusion. A new analytical solution is presented which reduces to a previous solution when axial diffusion is negligible. The effects of axial diffusion and ohmic potential drop in the pore electrolyte on the current and concentration distributions inside the electrode are investigated. Experimental confirmation is presented for some of the predictions and a quantitative comparison between theory and experiment is presented. It is concluded that axial diffusion effects are negligible under many experimental conditions, e.g., normal diffusion coefficient, flow rate, electrode length, etc. The results demonstrate the validity of the one‐dimensional model presented here under these conditions.