Fe3C Decorated N, Fe Co‐Doped Hollow Carbon Microspheres as Efficient Air Electrode Catalyst for Zinc‐Air Battery

Abstract Efficient metal‐air batteries need active catalysts with low cost for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, hollow spherical Fe−M/G/H catalyst was synthesized through a polycondensation/pyrolysis method without template. Polycondensation of melamine, d‐glucose, and hexamethylenetetramine was accomplished to obtain carbon spheres with high nitrogen content. Hollow microspheres containing Fe‐N x and Fe 3 C were fabricated by subsequent pyrolysis with Fe catalysts. Hollow microsphere structures not only expose more active sites (doped‐N, Fe‐N x , and Fe 3 C), but also promote the mass transfer of O 2 . Fe−M/G/H possesses superior ORR performance in alkaline media with high limiting current density (5.09 mA cm −2 ) and half‐wave potential (0.80 V). The OER activity of Fe−M/G/H is superior to commercial Pt/C. Fe−M/G/H assembled zinc‐air battery exhibits high peak power density (90.27 mW cm −2 ) and long stability. This research provides a new approach to design hollow carbon catalysts with homo‐dispersed Fe‐N x /Fe 3 C active sites and high doped‐N concentration.