Catalysts and catalyst-layers in ht-pemfcs

Abstract

High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) need to improve their lifetime! Especially, catalysts and catalyst-layers (CL) can degrade fast and severely. It is therefore sensible to explore new opportunities to increase their durability on an operational and material-based level. In order to achieve this goal, it is furthermore necessary to establish reliable characterization methods for CLs. In this chapter, several methods are discussed which help to shed more light onto the nature of CLs. Techniques for reproducible and spatially resolved in situ measurements of the electrochemically active surface area (ECSA) are introduced. Moreover, two CL degradation mitigation strategies are discussed. The first strategy is based on intentionally increased CO partial pressures at the fuel electrode during fuel cell start-up and shut-down. The second approach utilizes graphitized carbon support, which is less vulnerable to start-/stop-induced carbon oxidation. Overall, this chapter tries to open a small window for new insights into properties and characterization of HT-PEMFC catalyst layers.