Impact of Accelerated Stress Tests on the Cathodic Catalytic Layer in a Proton Exchange Membrane (PEM) Fuel Cell Studied by Identical Location Scanning Electron Microscopy

Platinum is the most used electrocatalyst in proton exchange membrane fuel cells (PEMFCs). Nonetheless, it suffers from various types of degradation. Identical location electron microscopy has previously been to observe local catalyst changes under accelerated stress tests (ASTs), giving insight into how individual particles degrade. However, important that such studies are carried out relevant reaction conditions, as these can differ substantially between liquid half-cells and real PEMFC conditions. In this work, a single cell was study degradation commercial Pt-catalyzed electrode assembly by performing square wave voltage ASTs potential range 0.6 1.0 V. scanning (IL-SEM) follow cathodic catalytic layer (CL) throughout 14,000 AST cycles. From IL-SEM, we conclude Pt nanoparticles degrade via Ostwald ripening, crystal migration, coalescence. Small agglomerate larger or dissolve redeposit more stable particles, increasing average particle size during ASTs. addition, cross-sectional TEM images show thinning ionomer procedure. The IL-SEM technique facilitates observation CL PEMFCs, which will help understand different mechanisms, allowing for better solutions be designed.