Impacts of Ru Dissolution and Crossover on Polymer Electrolyte Membrane Fuel Cell Performance and Anode Functionality

Carbon-supported PtRu catalysts are commonly used as anode catalysts in polymer electrolyte membrane fuel cells (PEMFCs) to provide CO tolerance for reformate fuel applications. However, Ru dissolution and subsequent crossover from the anode to the cathode have been identified as critical durability issues. In this investigation, half-cell electrochemical studies were carried out to characterize the changes and impacts imposed by Ru contamination on the cathode. In addition, an anode accelerated stress test (AST) was employed in a fuel cell to simulate potential spikes that occur during fuel cell start-ups and shutdowns to induce Ru dissolution and crossover. The electrochemical experiments showed that the oxygen reduction reaction (ORR) activity and the changes in cyclic voltammetry (CV) characteristics correlated well with the amount of Ru deposited on the cathode. From the single-cell AST results, it was evident that both the performance and CO tolerance were severely impacted by Ru dissolution and crossover.