The morphology of carbon supports critically governs oxygen transport and electrochemical performance in proton exchange membrane fuel cell (PEMFC) cathode catalyst layers. Here, we develop a pore-scale modeling framework coupling stochastic three-dimensional reconstruction and a lattice Boltzmann diffusion-reaction model to resolve local oxygen concentration, reaction rate, electrochemically active surface area, and current density. Optimized ellipsoidal supports with a semiaxis of 60 nm enhance pore connectivity and oxygen utilization, increasing peak current density by 18% compared with the spherical baseline and raising ionomer-phase oxygen concentration by 25%. Bowl-shaped supports with Rinner = 31 nm also improve performance, achieving a current density of 429.1 mA/cm2 and an oxygen concentration 12% higher than the baseline, whereas plate-shaped supports induce severe oxygen depletion near the membrane, reducing current density to 189.2 mA/cm2. CNT supports improve transport pathways but yield limited gains, with oxygen concentration increasing by 8% due to constrained active site utilization. These quantitative results establish clear morphology-structure-performance relationships, providing theoretical guidance for the design of high-performance, low-Pt PEMFC cathode catalyst layers.
Zhang et al. (Wed,) studied this question.