Biomass-derived single atom catalysts with phosphorus-coordinated Fe-N₃P configuration for efficient oxygen reduction reaction

Exploiting non-precious metal catalysts with excellent oxygen reduction reaction (ORR) performance for energy devices is paramount essential for the green and sustainable society development. Herein, low-cost, high-performance biomass-derived ORR catalysts with an asymmetric Fe-N₃P configuration was prepared by a simple pyrolysis-etching technique, where carboxymethyl cellulose (CMC) was used as the carbon source, urea and 1,10-phenanthroline iron complex (FePhen) as additives, and Na₃PO₄ as the phosphorus dopant and a pore-forming agent. The CMC-derived FeNPC catalyst displayed a large specific area (BET:1235 m² g^-1) with atomically dispersed Fe-N₃P active sites, which exhibited superior ORR activity and stability in alkaline solution (E_1/2 = 0.90 V vs. RHE) and Zn-air batteries (P_max = 149 mW cm^-2) to commercial Pt/C catalyst (E_1/2 = 0.87 V, P_max = 118 mW cm^-2) under similar experimental conditions. This work provides a feasible and cost-effective route toward highly efficient ORR catalysts and their application to Zn-air batteries for energy conversion.