Simulating Transient Pore-Scale Behaviour of Platinum Degradation in PEM Fuel Cells Using Pore Network Modeling

Limiting the degradation of platinum catalysts in the cathode catalyst layer (CCL) of polymer electrolyte membrane fuel cells remains a critical challenge for commercialization. In this work, a novel transient pore-scale model of platinum degradation was developed using pore network modeling. A two-dimensional artificial image of the CCL was generated to serve as the geometric basis. The modeling technique involved coupling a performance solver that simulated the oxygen reduction reaction with a degradation solver that accounted for platinum dissolution, oxide formation, and oxide dissolution. Platinum mass loss into the membrane was incorporated via a simplified membrane sink model. The results reproduce degradation trends such as spatial variations in surface area loss and transient changes in platinum oxide coverage and platinum ion concentration. Crucially, the model has the ability to uncover new microstructural insights, including how constrictions between agglomerates lead to localized degradation and how longer transport paths correlate with reduced platinum loss. The developed model provides a foundation for optimizing and designing the CCL pore structure to mitigate degradation and enhance fuel cell durability.