Nafion  , a perfluorinated sulfonic acid ionomer (PFSA)-based membrane, is commonly added to catalyst mixture as a supporting material to enhance catalyst dispersion. However, owing to its binding properties, the catalysts are prone to aggregation and overlapping, drastically reducing active surface area. In our modelling approach, we treat the catalyst as flooded agglomerates, considering them to be overlapping spherical structures with a thin film of ionomer around them as shown in Fig. .