Impact of Fabrication and Testing Parameters on the Performance of a Polymer Electrolyte Fuel Cell with Platinum Group Metal (PGM)-Free Cathode Catalyst

Abstract

Extensive research efforts have been made on platinum group metal (PGM)-free electrocatalysts for oxygen reduction reaction, with the aim of lowering the cost hurdle of acidic polymer electrolyte fuel cells (PEFCs). While the activity and durability of PGM-free catalysts have been boosted, the PEFC performance relies also on the electrode structure at the membrane electrode assembly (MEA) level. However, the extensive number of variables involved in the electrode preparation as well as in the fuel cell testing, poses severe challenge to compare results obtained in different labs. In this work, we systematically investigated the effect on performance of some operational variables, such as polarization curve scan direction, and gas flow rates. Additionally, anodic Pt catalyst loading and cathodic PGM-free catalyst loading were investigated. The tests were done in a differential cell hardware using a commercial Fe-N-C catalyst at the cathode. The results indicate that PGM-free catalyst loading and air flow rate on the cathode are impactful variables. Polarization curve scan direction (also considering averaging process on multiple consecutive scans), anode Pt loading as low as 0.035 mg cm−2, as well as H2 and O2 flow rates above 300 scm3 min−1 have negligible impact on the performance of PGM-free based MEAs.