Synergy between Intermetallic Pt Alloy and Porous Co–N4 Carbon Nanofibers Enables Durable Fuel Cells with Low Mass Transport Resistance

The complex chemical environments and strictly limited mass transport in the catalytic layer (CL) of proton exchange membrane fuel cells (PEMFCs) seriously hinder their performance. In this study, a one-dimensional atomically dispersed Co–N4/C porous carbon nanofiber (Co–N–PCNF) supported intermetallic L10-PtCo nanoparticle is developed as an advanced PEMFC cathode via electrospinning. Thanks to the suitable pore structure and homogeneous ionomer distribution, this unique CL exhibits an excellent pressure-independent oxygen transport resistance (RO2PI = 0.0321 s cm–1) and favorable ionomer-catalyst contact (92% dry proton accessibility) in an H2–air fuel cell. It also reveals a high initial mass activity (0.61 A mgPt–1) and extraordinary durability with MA retention of 99 and 73% after 50,000 and 100,000 cycles, respectively, exceeding the U.S. DOE 2025 targets and representing one of the most durable fuel cell catalysts ever reported. Density function theory calculations reveal that the rapid migration and decomposition of H2O2 from the Co–N4 site to L10-PtCo is the key to the accelerated oxygen reduction kinetics and the stronger binding between Co–N–PCNF and L10-PtCo compared to carbon support accounts for the much improved stability.