Pore-scale study of gas transport in catalyst layers of PEMFCs

In this study, pore-scale simulations are conducted to study oxygen transport processes around a carbon particle. Four-constituent microscopic structures of catalyst layer are reconstructed, which account for a carbon particle, ionomer, Pt particles, and primary pores inside the carbon particle. A physicochemical model is developed, which focuses on local oxygen transport processes around a carbon particle including oxygen dissolution at the pore/ionomer interface, oxygen diffusion within the thin ionomer film covering the carbon particle and inside the primary pores filled with water, and electrochemical reactions at the Pt interface. The lattice Boltzmann method is adopted to simulate above reactive transport processes at the pore scale, and oxygen transport resistance is calculated based on the concentration filed obtained. Effects of reactive transport condition, interfacial dissolution rate, Pt loading on the local transport resistance are investigated in detail. The simulation results are compared with experimental results and 1D models in the literature.