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Investigation of the diffusion of ferricyanide through porous membranes using the SECM150 – Scanning Probes. Application Note 19.

Latest updated: May 6, 2020

Abstract

Scanning ElectroChemical Microscopy (SECM) allows spatial resolution of porous membranes in x, y, and z directions. Using the SECM150 the diffusion of [Fe(CN)6]3- through a polycarbonate membrane with 12 µm pores was measured. By changing the probe to membrane distance quantitative analysis of diffusion through the membrane was performed.

 

Introduction

Scanning ElectroChemical Microscopy (SECM) has the ability to provide spatially resolved, rather than globally averaged, measurements of a system. This is particularly useful for measurements of membranes, and other porous systems through which diffusion of a species can occur. In these cases SECM provides not only spatial resolution in the x,y direction, but can also allow investigation in z. This gives perspective on the diffusion of the species of interest through the pore, and within the electrolyte after leaving the pore. At present, there have been limited studies of gas diffusion electrodes by SECM [1]. However, growing interest in fuel cells and metal-air batteries means the use of SECM in future such measurements is likely. The measurement of simple porous membranes provides a background understanding of the concepts and experimental requirements of measuring more complex diffusion systems. Furthermore, these experiments demonstrate the usefulness of SECM in diffusion measurements. The use of the SECM150 to measure the diffusion of the [Fe(CN)6] 3- redox mediator through a porous membrane will be demonstrated in this note.

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