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

It is highly desirable to develop high-efficiency non-precious electrocatalysts toward oxygen reduction reaction (ORR). In this work, Fe 2 O 3 -encapsulated and Fe-Nx-containing porous carbon spheres (Fe 2 O 3 /N-MCCS) with unique multi-cage structures and high specific surface area (1360 m 2  g −1 ) are fabricated. The unique porous structure of Fe 2 O 3 /N-MCCS ensures fast transportation of oxygen during ORR. The combined effect of Fe 2 O 3 nanoparticles and Fe-Nx configurations endows Fe 2 O 3 /N-MCCS (E 1/2  = 0.837 V vs. RHE) with superior ORR activity and methanol tolerance to Pt/C. And, Fe 2 O 3 /N-MCCS exhibits better stability than nitrogen-modified carbon. The characterization results of Fe 2 O 3 /N-MCCS after long-term test reveals its excellent structural stability. Impressively, zinc-air battery based on Fe 2 O 3 /N-MCCS showed a peak power density of 132.4 mW cm −2 and a specific capacity of 797 mAh g −1 , respectively.