The Dissolution Dilemma for Low Pt Loading Polymer Electrolyte Membrane Fuel Cell Catalysts
Daniel J. S. Sandbeck, Niklas Mørch Secher, Masanori Inaba, Jonathan Quinson, Jakob Ejler Sørensen, Jakob Kibsgaard, Alessandro Zana, Francesco Bizzotto, Florian Speck, Michael T. Y. Paul, Alexandra Dworzak, Carsten Dosche, Mehtap Oezaslan, Ib Chorkendorff, Matthias Arenz, Serhiy Cherevko
Abstract
Cost and lifetime currently hinder widespread commercialization of polymer electrolyte membrane fuel cells (PEMFCs). Reduced electrode Pt loadings lower costs; however, the impact of metal loading (on the support) and its relation to degradation (lifetime) remain unclear. The limited research on these parameters stems from synthetic difficulties and lack of in situ analytics. This study addresses these challenges by synthesizing 2D and 3D Pt/C model catalyst systems via two precise routes and systematically varying the loading. Pt dissolution was monitored using on-line inductively coupled plasma mass spectrometry (on-line-ICP-MS), while X-ray spectroscopy techniques were applied to establish the oxidation states of Pt in correlation with metal loading. Dissolution trends emerge which can be explained by three particle proximity dependent mechanisms: (1) shifts in the Nernst dissolution potential, (2) redeposition, and (3) alteration of Pt oxidation states. These results identify engineering limitations, which should be considered by researchers in fuel cell development and related fields.