Controlled preparation of Fe-N-C catalyst with ordered macroporous framework for superior acidic oxygen reduction performance

The non-precious metal Fe-N-C catalyst is regarded as a potential substitute for the precious metal catalysts for the oxygen reduction reaction (ORR) application. However, its catalytic activity and stability still fall short of those of the precious metal catalysts. Here, Fe-N-C catalyst with an ordered macroporous framework was achieved through using polystyrene (PS) as templates. The results indicate the particle size and structural orderliness of PS templates have great influence on the morphology and the catalytic performance of the obtained Fe-N-C catalysts. The optimized catalyst, derived from ordered PS with 200 nm, exhibits exceptional ORR activity in acidic media with a half-wave potential of 0.885 V (vs. RHE), surpassing commercial Pt/C (0.847 V) and Fe-N-C without PS counterparts (0.796 V), and superior mass activity (26.54 A g⁻¹, 0.8 V) and kinetic current density (14.7 mA cm⁻²,0.85 V), while maintaining outstanding durability under 30,000 potential cycles (18 mV loss). The catalyst, as the cathode in an H₂/O₂ fuel cell, exhibits a peak power density of 0.83 W cm⁻². This excellent activity arises from its regular morphology combined with ordered macroporous framework facilitating active site exposure and reactant diffusion. The regularly arranged template-induced structural ordering enhances the graphitization and integrity of carbon matrix during pyrolysis, promoting the stability. These findings establish a template-size-dependent design principle for non-precious metal catalysts, offering a viable pathway to balance activity-stability trade-offs in proton-exchange membrane fuel cells and related electrochemical energy technologies.