Preparation of PEMFC Electrodes from Milligram-Amount Catalysts

Abstract

Thin film rotating disk electrode (RDE) measurements have been commonly used for activity and stability measurements of catalysts for proton exchange membrane fuel cells (PEMFCs). However, many catalysts that exhibit excellent activity and stability in an RDE do not show acceptable performance in an actual fuel cell using a membrane electrode assembly (MEA). This could be due to differences in the measurement conditions and the stability of the catalysts. This shows the importance of measuring the activity and durability of catalyst materials using an MEA in an actual fuel cell. However, MEA electrode preparation traditionally involves ink making and coating, processes that commonly require a large amount of catalyst material (>1 g) in order to prepare a well performing MEA. This creates a significant challenge for catalyst development because in early stages only mg amount are usually available and up-scaling efforts can be expensive and time consuming. In this study, we developed two techniques to fabricate fuel cell electrodes from a small amount of catalyst (ca 30 mg): one using vacuum filtration and one using ultrasonic spray coater. The electrodes can then be used to fabricate MEAs. The fabrication procedure, the characterization of electrode quality, and the electrochemical properties will be discussed in comparison to MEA prepared by a traditional ‘large-catalyst-quantity’ process. A recommended procedure for MEA fabrication from mg-quantity catalyst samples will be provided. This work was partially supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy under grant DE-EE0007271.