Proton exchange membrane fuel cells (PEMFCs) are considered a significant player in the hydrogen economy. However, before mass production is possible, significant improvements in durability are necessary. Monitoring the changes in the electrode structure is challenging without a complex measurement apparatus. Precisely, the changes in electrode properties during carbon corrosion (increase in the porosity and electrode collapse) cannot be quantified using conventional electrochemical methods. Here, we report capturing the oxygen diffusivity in the PEMFC cathode catalyst layer using low-frequency electrochemical impedance spectroscopy (0.3-0.01 Hz). The low-frequency arc is fitted with resistance, inductance, and capacitance in parallel to represent the resistance to oxygen supply, inertia to oxygen diffusion, and oxygen storage capacity in the catalyst layer, respectively. Over 600 cycles of accelerated stress test (ASTs) of carbon corrosion, the capacitance increases by 25–45% (0–150 ASTs), indicating an increase in oxygen storage capacity and electrode porosity. Then, (150–600 ASTs) the resistance and inductance increase while the capacitance decreases by 80%, highlighting a decrease of the oxygen diffusivity and storage in the catalyst layer as the electrode collapses, which causes oxygen starvation. Altogether, this low-frequency approach correlates electrochemical impedance measurements with the changes in electrode structure during carbon corrosion.

质子交换膜燃料电池（PEMFC）被认为是氢经济的重要参与者。然而，在可能的大规模生产之前，必须显着提高耐久性。在没有复杂的测量设备的情况下，监测电极结构的变化具有挑战性。准确地说，碳腐蚀过程中电极性能的变化（孔隙率增加和电极塌陷）无法使用常规的电化学方法进行量化。在这里，我们报告使用低频电化学阻抗谱（0.3-0.01 Hz）捕获PEMFC阴极催化剂层中的氧扩散率。低频电弧并联有电阻，电感和电容，以表示对氧气供应的抵抗，对氧气扩散的惯性，催化剂层中的氧存储能力和氧存储能力。在600次以上的碳腐蚀加速应力测试（AST）循环中，电容增加了25–45％（0–150 ASTs），表明氧气存储能力和电极孔隙率增加。然后，（150-600 ASTs）电阻和电感增加，而电容减小80％，这突出表明随着电极的塌陷，氧扩散率和在催化剂层中的存储减少，这会导致缺氧。总之，这种低频方法将电化学阻抗测量结果与碳腐蚀过程中电极结构的变化相关联。表示储氧能力和电极孔隙率增加。然后，（150-600 ASTs）电阻和电感增加，而电容减小80％，这突出表明随着电极的塌陷，氧扩散率和在催化剂层中的存储减少，这会导致缺氧。总之，这种低频方法将电化学阻抗测量与碳腐蚀期间电极结构的变化相关联。表示储氧能力和电极孔隙率增加。然后，（150-600 ASTs）电阻和电感增加，而电容减小80％，这突出表明随着电极的塌陷，氧扩散率和在催化剂层中的存储减少，这会导致缺氧。总之，这种低频方法将电化学阻抗测量与碳腐蚀期间电极结构的变化相关联。