The typical catalyst layers (CLs) in proton exchange membrane fuel cells (PEMFCs) are fabricated as random heterogeneous composites to meet the multifunctional requirements of transport phenomena and electrochemical activity. The employment of Pt nano-particles, carbonaceous substrates and Nafion ionomers in CLs allows effective diffusion of hydrogen and oxygen, transport and phase change of water, migration and diffusion of protons, migration of electrons to and from the catalytic sites, which is accompanied by the oxidation of hydrogen in anodes and the generation of water and heat in cathodes. Based on the coarse-grained (CG) molecular dynamics method, a systematic technique is developed to provide insight into the self-organization phenomena and the microscopic spatial structure of the CLs. The formation of a CL is simulated by considering the interactions of the Pt clusters, carbon slabs, Nafion ionomers, hydronium ions and water. Meanwhile, the morphologies of Pt clusters are presented and compared with three cases. Moreover, the pair correlation functions (PCFs) are employed to predict the distributions and hydrophilic properties of the components. Finally, the TPB features are shown at the nano-scale level, which provides deeper view to understand the Pt utilization in the CLs.

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