Mesoporous Fe‐Nx‐C Sub‐Microspheres for Highly Efficient Electrocatalytic Oxygen Reduction Reaction

Abstract

AbstractWe design and obtain mesoporous Fe‐Nx‐C sub‐microspheres (Meso Fe‐Nx‐C‐SS) using the amino acid‐metal complex as Fe/N/C precursor and mesoporous silica sub‐microspheres (MSS) as hard template by a facile template‐assistance strategy. The Histidine‐Fe complex is impregnated into mesopores of MSS, and then Meso Fe‐Nx‐C‐SS are obtained by high‐temperature carbonization process and removal of MSS template. The as‐fabricated Meso Fe‐Nx‐C‐SS exhibits the spherical structure with rough surface with the diameter size of 200–500 nm. And Meso Fe‐Nx‐C‐SS also possesses a high specific surface area of 784 m2 g−1, a large pore volume of 1.65 cm3 g−1, and a large pore size in the range of 10–22 nm. Benefiting from atomically dispersed N‐coordinated Fe and unique three‐dimensionally (3D) interconnected mesoporous carbon architecture, Meso Fe‐Nx‐C‐SS shows excellent electrocatalytic performance toward oxygen reduction reaction (ORR) with positive half‐wave potential (E1/2 0.86 V), high stability (93.94 % after 30,000 s), low Tafel slop (43 mV dec−1) and good methanol tolerance, exceeding commercial Pt/C catalyst in alkaline media. As the cathode catalyst within the primary Zn‐air batteries, Meso Fe‐Nx‐C‐SS also reveals an outstanding catalytic activity (the maximum power density of 120 mW cm−2) and superior discharge stability (at current density of 10 mA cm−2 after 6 cycles, at different current densities of 5, 10, 20 mA cm−2), promoting its practical application in Zn‐air batteries.