Lignin‐Based Nitrogen‐Doped Porous Carbon Nanosheets Supported With Fe ₃ C Nanoparticles as Bifunctional Oxygen Electrocatalyst for Zinc‐Air Batteries

The development of high‐performance bifunctional electrocatalysts for oxygen reduction (ORR) and oxygen evolution reaction (OER) from biomass‐derived materials represents a promising route toward sustainable energy technology. Herein, using alkaline lignin as the renewable precursor and melamine as the nitrogen dopant, Fe 3 C/NC electrocatalysts were synthesized through NaCl template‐assisted pyrolytic process. This synthetic route generates an interconnected three‐dimensional (3D) porous network for the catalysts. Benefiting from the synergistic effect between Fe 3 C and active N species, high specific surface area, and rich porous architecture, the resulting material exhibits an ORR half‐wave potential ( E 1/2 ) of 0.855 V, an OER overpotential ( η 10 ) of 328 mV, and a potential gap (Δ E ) of 0.703 V, demonstrating the excellent bifunctional activity. Moreover, zinc‐air batteries constructed with Fe 3 C/NC cathodes deliver high open‐circuit voltage, large specific capacity, as well as outstanding cycling stability. These results provide valuable insights for the design of sustainable, biomass‐derived bifunctional electrocatalysts for clean energy applications.