Multifunctional layer coupling in hybrid carbon nanotube networks enables high-performance catalyst layer in proton exchange membrane fuel cell

The transition towards low-carbon transport demands a proton exchange membrane fuel cell (PEMFC) with both high efficiency and robust operational stability. Under real operating conditions, the coupling of charge transfer, gas transport, and moisture distribution within fuel cells introduces systemic complexity and poses challenges for catalytic material design. Here, guided by a multifunctional layer coupling strategy, this work achieves multiscale synergistic optimisation from microscopic conductive backbone construction, through mesoscale reaction-interface regulation, to macroscopic integration of membrane-electrode-assembly (MEA) functional layers, by means of controllable surface functionalisation and support hybridisation. Mildly oxidised multi-walled carbon nanotubes (MWCNTs) were engineered to establish a conductive core-reactive interface, preserving the graphitic backbone for electron transport whilst introducing an oxygen-containing outer layer for controlled Pt anchoring. When blended with carbon black (CB), the resulting MWCNT-CB hierarchical conductive framework enhances Pt accessibility, reconstructs transport pathways and improves PEMFC performance under operating conditions. In small-scale cells, the optimised Pt/MWCNT-CB 1:1 catalyst delivered a 68% increase in peak power over Pt/CB. Under automotive-relevant conditions, it achieved 1535 mW cm−2, surpassing the U.S Department of Energy (DOE) targets. Durability testing following DOE protocols confirmed suppressed Pt migration and reduced carbon corrosion. The predicted operational lifetimes of Pt/MWCNT (6 h oxidation) and Pt/MWCNT-CB 1:1 were 16,906 and 14,761 h, respectively, with start-up/shut-down tolerances of 15,110 and 6060 cycles. Both metrics exceed the DOE ultimate durability targets for light-duty fuel cell vehicles (8000 h operation and 5000 start-up/shut-down cycles), highlighting a practical route towards durable, high-performance catalysts for light-duty fuel cell vehicles.