Sulfur dioxide is a common air pollutant that has an adverse impact on proton exchange membrane fuel cells (PEMFCs). The present study reports the spatial performance and degradation of low-Pt PEMFCs exposed to trace concentrations of SO₂ in a cathode feed stream. PEMFCs exposed to 2 ppm SO₂ resulted in a performance loss of 240 and 345 mV for constant current holds of 0.2 and 0.8 A cm⁻². However, the SO₂ contamination of low-Pt fuel cells at 1.0 A cm⁻² led to a drastic cell potential drop below 0.1 V from the initial 0.605 V and demonstrated that the cathode exposure to SO₂ should be limited to concentrations significantly below 2 ppm for high power operating conditions. The observed voltage and spatial current behavior was attributed to the reduction of SO₂ on Pt to zero-valent sulfur at potentials below 0.6 V. PEMFCs recovered performance only after potential cycling, insuring the oxidation of the formed S⁰ species at potentials higher than 0.8 V. A comparison of the electrochemical parameters before and after PEMFC poisoning revealed a substantial decrease in electrochemical surface area of up to 45.2% and a final performance loss of 60–100 mV.

二氧化硫是一种常见的空气污染物，会对质子交换膜燃料电池（PEMFC）产生不利影响。本研究报告了在阴极进料流中暴露于痕量SO ₂的低Pt PEMFC的空间性能和降解。暴露于2 ppm SO _2的PEMFC导致在0.2和0.8 A cm ^-2的恒定电流保持下，性能损失为240和345 mV 。然而，低铂燃料电池在1.0 A cm ^-2的SO ₂污染导致电池电势从最初的0.605 V急剧下降到0.1 V以下，这表明阴极暴露于SO ₂对于高功率工作条件，应将浓度限制在明显低于2 ppm的范围内。观察到的电压和空间电流行为归因于在低于0.6 V的电势下Pt上的SO ₂还原为零价硫。PEMFC仅在电势循环后才能恢复性能，确保在高于0.8的电势下形成的S ⁰物种被氧化V. PEMFC中毒前后的电化学参数比较显示，电化学表面积大幅度降低了45.2％，最终性能损失为60-100 mV。