Proton Exchange Membrane Water Electrolyzer Cathode: A Nanomechanical and Nanoelectrical Analysis

Investigating the aging of proton exchange membrane electrolyzer cells (PEMECs) is crucial for extending their lifetime. Thus, nanomechanical and nanoelectrical atomic force microscopy (AFM) techniques and nanoindentation were employed on a more than 5000 h operated web-woven reinforced membrane electrode assembly (MEA) cathode. Upon operation, a heterogenization and a slight increase in the mean reduced modulus and hardness was observed by nanoindentation. AFM revealed the surface distribution of low stiffness and electrically non-conductive ionomer and high stiffness electrically conductive catalyst particles on the pristine and operated cathodes. The μ m sized ionomer plateaus on the surface exhibit a stable nature, as their stiffness and their frequency on the surface remained constant. The operated cathode’s catalyst equally stiffened at the two analyzed domains—at positions within carbon fiber (CF) porous transport layer (PTL) imprints and outside of imprints. Thus, no enhanced aging due to local compression is indicated. This study enhances the understanding of cathode aging with respect to the PTL.