A Scalable Mesoporous Catalyst with Intrinsic Water Retention and Ultra-Stability for High-Performance Low-Humidity Fuel Cells

Proton exchange membrane fuel cells (PEMFCs) are increasingly shifting toward low-humidity operation to simplify systems and improve efficiency, necessitating advanced electrocatalyst designs. Herein, we present a mesopore-confined platinum (Pt) catalyst with a high Pt site density that effectively addresses key challenges under dry conditions. The abundant mesopores enhance water retention via capillary condensation, while the high Pt density shortens the nearest-neighbor distance, maintaining continuous proton pathways under low humidity. Additionally, mesopore confinement suppresses Ostwald ripening, significantly enhancing durability. In single-cell tests under H 2 /air (0.5/2 L min –1, 150 kPa back pressure), the mesoporous carbon-based MEA (m-MEA) achieved 0.719 V at 2000 mA cm –2, exceeding the porous carbon-based MEA (p-MEA) by 58 mV. In a liquid-cooled stack (H 2 /air, stoichiometry 1.8/2, 50% relative humidity (RH), 150 kPa back pressure), it reached 0.700 V at 2000 mA cm –2, with a 64 mV improvement. Under fan-forced air and ambient pressure, the m-MEA maintained 0.732 V at 500 mA cm –2, surpassing the p-MEA by 81 mV. After 30,000 accelerated stress test (AST) cycles, the m-MEA showed only 26 mV decay at 800 mA cm –2, 61.7% lower than the p-MEA’s 68 mV decay, meeting DOE 2025 target of 30 mV.