Phosphorus-induced electronic coupling between Fe single atoms and Fe2O3 nanoparticles on biomass-derived carbon for efficient oxygen reduction

Abstract

Developing non-noble metal catalysts with both high activity and stability for the oxygen reduction reaction (ORR) remains a major challenge. Herein, we report a phosphorus-induced electronic coupling strategy to construct a dual-active-site catalyst composed of Fe single atoms and Fe₂O₃ nanoparticles anchored on a hierarchically porous carbon matrix derived from sugarcane bagasse biochar (Fe–P–C–Fe₂O₃/SBB). Phosphorus doping modulates the local coordination environment and facilitates the formation of Fe–P–O bonds, which bridge Fe single atoms and Fe₂O₃ nanoparticles, enabling interfacial charge redistribution. This electronic coupling optimizes the Fe d-band center, balances the adsorption strength of oxygen intermediates, and promotes a four-electron ORR pathway. As a result, the Fe–P–C–Fe₂O₃/SBB catalyst delivers a half-wave potential of 0.80 V (vs. RHE) and a Tafel slope of 75.6 mV dec⁻¹, rivaling commercial Pt/C. Notably, the achieved ORR performance is comparable to or surpasses that of many recently reported non-noble metal catalysts, highlighting its strong potential for practical applications in fuel cells and metal–air batteries. Moreover, the catalyst exhibits remarkable durability and methanol tolerance. This work not only provides an atomically and electronically coupled Fe-based catalytic system but also offers a general strategy for designing sustainable biomass-derived dual-active-site catalysts through heteroatom-induced electronic coupling.