Comparing Different Cross-Section Cutting Methods for SEM Analysis of Membrane-Electrodes Assemblies

Abstract

A study is presented to compare different methodologies for the cross-sectional visualization of membrane-electrode assemblies (MEAs) with SEM. Four techniques for cutting MEAs have been tested and analyzed: the sharp-edge cutting, CO2 laser, embedded-mechanical polishing, and ion-milling. Characteristics of each procedure are compared. Sharp-edge cutting, being fast and low cost, may preserve layers porous morphology rather unaltered, but obtaining a good cross-section in a wide area is stochastic and with low probability. CO2-laser beam cutting alters severely carbon and Nafion layers as a consequence of the burning of carbon based materials. Embedded-mechanical polishing is a well stablished and reproducible method that shows accurately the thickness of the layers, however it is too aggressive with highly porous structures that may appear smoothed or removed. Ion-milling is also good for accurate thicknesses measurements, and more conservative with the porous morphologies than the previous one, but they are also smoothed.