With an attempt to design fuel cell catalyst layers with low Pt loading capable of delivering suitable performance and life expectancy, interfacial interactions between the different phases need to be improved. In this aspect, modulating the distribution of ionomers in the cathode catalyst layer is an interesting direction that is worth exploring as it can provide a highly connected proton conducting network in addition to reducing transport limitations.

In the present work, microstructural realisations are achieved through tomography data based on focused ion beam scanning electron microscopy (FIB-SEM) to obtain the Pt/C phase and an interfacial energy based erosion model to generate the ionomer phase. These microstructural features are then deployed to a catalyst layer based transport model to address the interplay of geometrical stochasticity and operating conditions such as relative humidity. The microstructural heterogeneity is thus investigated to unravel the structure-transport-property interactions of Pt-C and ionomer phases to provide a comprehensive understanding of the electrochemical performance.