Characterization of porous electrodes using surface-limited electrochemical reactions: Quantification of the effective diffusion coefficient

Abstract

The effective diffusion coefficient of electroactive species in porous electrodes is a key parameter determining their performance. However, methods to conveniently and accurately measure this parameter are still lacking. In this work, we demonstrate that combining a surface-limited process, Cu underpotential deposition on a high surface area porous Pt electrode, with a rotating disk electrode system, allows for the accurate determination of the effective diffusion coefficient. Equations describing the mass transport-limited surface-limited reactions were developed, allowing not just the effective diffusion coefficient, but also the bulk diffusion coefficient, surface area, and more information regarding the external mass transport in the cell to be obtained.