Porous Carbon Spheres with Ultra-fine Fe2N Active Phase for Efficient Electrocatalytic Oxygen Reduction

In this work, hierarchically porous carbon spheres co-doped by iron and nitrogen were synthesized via in situ dehalogenation. The rich porous structure and relatively high specific surface area (210 m 2 /g) facilitate the formation of an ultra-fine Fe 2 N active phase and FeN 4 active centers within the carbon matrix. Transmission electron microscopy and X-ray photoelectron spectroscopy analysis further reveal the presence of a dominant Fe 2 N phase and minor FeN 4 bonds in the as-prepared Fe-N-C-pd-800 samples. Because of this, the oxygen reduction reaction (ORR) process can more readily take place on Fe 2 N than on FeN 4 , and the Fe 2 N phase enriched Fe-N-C-pd-800 carbon spheres exhibit a promising onset potential ( E onset =1.02 V) and half-wave potential ( E 1/2 =0.86 V) in alkaline media. In addition, Fe-N-C-pd-800 also shows excellent methanol resistance and long-cycling stability.