Influence of Cathode Airborne Impurity Levels on PEMFC Durability during Accelerated Performance Testing

<p>Various contaminants present in cathode air streams may significantly affect the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, sulfur dioxide (SO2) and nitrogen dioxide (NO2) were selected as representative airborne impurities to quantitatively investigate their individual and combined effects on PEMFC performance. Experiments were conducted using five different NO2:SO2 mixture ratios (100:0, 75:25, 50:50, 25:75, and 0:100), while maintaining a constant total contaminant concentration as 100 ppm. The results revealed a pronounced decline in cell performance with increasing NO2 proportion, whereas performance degradation progressed more gradually with higher SO2 concentrations. Cyclic voltammetry (CV) analysis showed that SO2 exhibited strong and persistent adsorption on the platinum catalyst surface, which was not fully removed even after exposure to neat air during the recovery process. These findings were further supported by electrochemical impedance spectroscopy (EIS), indicating that SO2 contamination caused sustained increases in charge transfer resistance and a notable decrease in electrochemical active surface area. In contrast, NO2-contaminated systems exhibited comparatively faster performance recovery. This paper provides valuable insights into the degradation and recovery behaviors of PEMFCs under mixed-gas contamination, contributing to the development of effective mitigation strategies for improving fuel cell durability in polluted environments.</p>