The Dissolution Dilemma for low Pt Loading Polymer Electrolyte Membrane Fuel Cell Catalysts

Cost and lifetime currently hinder widespread commercialization of polymer electrolytemembrane fuel cells (PEMFCs). Reduced electrode Pt loadings lower costs; however, the impactof metal loading (on the support) and its relation to degradation (lifetime) remain unclear. Thelimited research on these parameters stems from synthetic difficulties and lack of in situanalytics. This study addresses these challenges by synthesizing 2D and 3D Pt/C model catalystsystems via two precise routes and systematically varying the loading. Pt dissolution wasmonitored using on-line inductively coupled plasma mass spectrometry (on-line-ICP-MS), whileX-ray spectroscopy techniques were applied to establish the oxidation states of Pt in correlationwith metal loading. Dissolution trends emerge which can be explained by three particleproximity dependent mechanisms: (1) shifts in the Nernst dissolution potential, (2) redeposition,and (3) alteration of Pt oxidation states. These results identify engineering limitations, whichshould be considered by researchers in fuel cell development and related fields.