Support-Geometry-Directed Multidimensional Pore Networks Enable High-Performance Low-Pt Fuel Cells

Oxygen transport in cathode catalyst layers remains a major barrier to high-performance low-Pt fuel cells, yet the pore-network features governing transport across length scales are poorly defined. Here we show that carbon-support geometry can direct the formation of accessible multidimensional pore networks in catalyst layers, thereby regulating oxygen transport under high-current operation. Thermolabile mixed-ligand zeolitic imidazolate frameworks were used as precursors to generate carbon supports with controlled particle size and surface concavity. Using these model supports, we establish how support geometry governs particle packing and catalyst-layer architecture. Combined focused ion beam-scanning electron microscopy and N₂ sorption analyses reveal that the optimal catalyst layer exhibits a porosity of 58.2%, an open-pore ratio of 99.6%, and a continuous pore-size distribution spanning sub-35 to 900 nm. This interconnected pore network lowers oxygen-transport resistance and improves the accessibility of the triple-phase boundary. Consequently, membrane electrode assemblies deliver a peak power density of 1.30 W cm⁻² under H₂-air at 0.05 mg_Pt cm⁻², outperforming commercial Pt/C and surpassing many reported Pt-based catalysts operated at higher loadings. Results identify multiscale pore network architecture as a key descriptor governing oxygen transport and provide a support-geometry-based strategy for designing transport-efficient low-Pt fuel-cell electrodes beyond conventional active-site optimization.