Three‐Dimensional Hierarchical Porous Fe, N‐Doped Hollow Carbon Nanospheres as Stable Electrocatalyst for Efficient Oxygen Reduction Reaction in Both Acidic and Alkaline Electrolytes

Abstract

3D hierarchical porous Fe, N‐doped hollow carbon nano‐spheres (Fe−N−C HPNCs) as efficient ORR electrocatalyst were obtained using melamine‐formaldehyde resin (MF) nanospheres as thermal sacrificial hard template to optimize the pore structure and provide nitrogen source to the catalyst. The optimized Fe−N−C HPNCs catalyst exhibited excellent catalytic activity with onset (Eonset) and half‐wave (E1/2) potential (Eonset=1.07 V; E1/2=0.90 V vs. RHE) superior to commercial Pt/C catalyst in 0.1 M KOH solution, and demonstrated excellent stability. When applied as cathode electro‐catalyst in a Zn‐air battery, it produced maximum power density (Pmax) of 127 mW cm−2, which is higher than that of commercial Pt/C (Pmax=119 mW cm−2). It also showed good activity (Eonset=0.89 V; E1/2=0.78 V) in 0.1 M HClO4 electrolyte with significantly enhanced stability (ΔE1/2=−7 mV) relative to the Pt/C catalyst (ΔE1/2=−27 mV).