PGM-Free Catalyst Modification for Air-Breathing Stacks

The operation and viability of an air-breathing fuel cell stack will heavily depend on the cleanest available local air, unless its cathode is tolerant to impurities. Previous research on the impact of air impurities showed deleterious impacts on overall performance utilizing platinum catalysts. To date, fuel cell research findings using air impurities employing non-platinum catalysts, platinum group metal-free (PGM-free), is scarce. To test the viability of a PGM-free stack, a miniature four-cell stack with PGM-free catalyst was assembled to compare with results from a standard eight-cell stack Pt-based catalyst, in both H2/Air and H2/O2. A promising open current voltage was obtained, offering a comparable statistic to what would be expected from a platinum-based stack of the same size. Prior research has shown higher performance for PGM-free membrane-electrode assemblies in terms of current density at the desired operating voltage, but significant performance loss after testing indicates poor stability. Repeated testing of the PGM-free stack showed such a decrease in current density performance at designated voltages after initial testing, followed by stability in results. Further testing with exposure to impurities is expected to demonstrate tolerance and reversibility in a PGM-free stack once initial stability is obtained. The purpose of this project is to develop a fuel-cell stack to meet specific power output requirements utilizing PGM-free cathode catalyst.