Fe–N–C catalyst with atomic Fe dispersion and hierarchical porosity <i>via</i> PVP-assisted MOF synthesis for ORR in acidic media

Iron-nitrogen-carbon (Fe-N-C) catalysts have emerged as leading non-precious metal catalyst (NPMC) candidates for the oxygen reduction reaction (ORR) in acidic media, yet challenges persist in achieving high activity, durability, and atomic-scale Fe dispersion. Here, we report Fe-ZIF-8-PVP-1000, a high-performance Fe-N-C catalyst synthesized <i>via</i> a polyvinylpyrrolidone (PVP)-assisted metal-organic framework (MOF) strategy. PVP functions as a morphology stabilizer, nitrogen dopant, and metal dispersant, producing atomically dispersed Fe-N _<i>x</i> sites within a hierarchically porous, nitrogen-rich carbon matrix. The catalyst achieves a half-wave potential (<i>E</i> _1/2) of 0.865 V <i>vs.</i> RHE in 0.5 M H₂SO₄, surpassing commercial 28.6 wt% Pt/C (<i>E</i> _1/2 ≈ 0.855 V) and rivaling the best Fe-N-C catalysts reported to date. With a BET surface area of 1579.8 m² g^-1 and a micropore volume of 0.54 cm³ g^-1, it provides abundant accessible active sites; electrochemical analysis further revealed an electron transfer number of <i>n</i> ≈ 3.96 with minimal H₂O₂ yield, confirming a highly selective four-electron ORR pathway. The catalyst retained approximately 84% of its current after 10 h and exhibited only an 11 mV negative shift in <i>E</i> _1/2 after 30 000 cycles, demonstrating outstanding stability. This scalable synthesis provides acid-tolerant, high-performance NPMCs with optimized structural and electronic properties.