Fe2O3-encapsulated and Fe-Nx-containing hierarchical porous carbon spheres as efficient electrocatalyst for oxygen reduction reaction

Abstract It is highly desirable to develop high-efficiency non-precious electrocatalysts toward oxygen reduction reaction (ORR). In this work, Fe2O3-encapsulated and Fe-Nx-containing porous carbon spheres (Fe2O3/N-MCCS) with unique multi-cage structures and high specific surface area (1360 m2 g−1) are fabricated. The unique porous structure of Fe2O3/N-MCCS ensures fast transportation of oxygen during ORR. The combined effect of Fe2O3 nanoparticles and Fe-Nx configurations endows Fe2O3/N-MCCS (E1/2 = 0.837 V vs. RHE) with superior ORR activity and methanol tolerance to Pt/C. And, Fe2O3/N-MCCS exhibits better stability than nitrogen-modified carbon. The characterization results of Fe2O3/N-MCCS after long-term test reveals its excellent structural stability. Impressively, zinc-air battery based on Fe2O3/N-MCCS showed a peak power density of 132.4 mW cm−2 and a specific capacity of 797 mAh g−1, respectively.