PEM-Fuel Cell Catalyst Behavior between Room Temperature and Freezing Point

An increasing use of fuel cell electric vehicles involves the need to understand their behavior at low ambient temperatures as well as under cold-start conditions. Here commercial 60 wt.% Pt/C catalyst (HiSPEC9100) was studied in the temperature range 0-20-°C using rotating disc electrode (RDE) setup and single cell inside a climate chamber. RDE measurements of oxygen reduction reaction (ORR) activity revealed decreasing activity with lower temperatures as well as activation energies and reaction mechanisms comparable to high temperature studies. Catalyst degradation was significantly lower at lower temperatures, which was confirmed by CO stripping. The increase of the specific ORR activity after degradation measurements is discussed in terms of morphological changes of the Pt particles. Single cell tests confirmed significant performance reduction at lower temperatures. Furthermore, measurements at different power densities were conducted to evaluate heating and flooding effects.