Dicyandiamide-driven surface reconstruction of high-loading highly-dispersed Fe-N-C catalysts for enhanced acidic durability

Abstract

The development of highly active and durable electrocatalysts with no platinum-group metals remains a critical challenge for the widespread commercialization of Proton-Exchange Membrane Fuel Cells. While Fe-N-C materials offer promising initial performance, their structural instability in acidic media limits their lifespan. In this work, a dicyandiamide-driven, post-synthetic restructuring strategy is presented. This post-treatment drives a nitrogen-rich surface reconstruction that coordinates and stabilizes a high density of active sites, nearly doubling the total iron content. While introducing a minor concession in initial mass activity (2.2 A/g at 0.85 V vs. 3.2 A/g for reference material), the optimized catalyst exhibits an exceptional durability in 0.5 M H 2 SO 4 , retaining 91% of its activity after 20,000 potential cycles, with only a 5 mV shift in half-wave potential, dramatically outperforming the reference catalyst. This enhanced longevity stems from the structural stabilization and local pore confinement offered by the reconstructed network, which effectively mitigates active-center demetallation pathways. The findings establish surface restructuring as a route for developing structurally robust materials, offering a promising foundation for future engineering into fuel cell cathode layers.