Self-template synthesis of Fe–Nx doped porous carbon as efficient oxygen reduction reaction catalysts in zinc air batteries

Abstract

Metal-nitrogen doped carbon materials (M/NCs) exhibit considerable potential as electrocatalysts for oxygen reduction reaction (ORR) in novel energy conversion and storage devices. Herein, the Fe–Nx doped porous carbon catalysts (FeNxPCs) with three-dimensional (3D) pore structure are synthesized by in situ pyrolyzation of polypyrrole-coated Fe2O3 (Fe2O3@PPy). Fe2O3 derived from the iron-formate framework (Fe-FF) is partially dissolved to generate Fe3+ for driving polymerization and served as template to form the 3D structure during polymerization. FeNxPCs exhibit satisfactory long-term durability and superior ORR activity (E1/2 = 0.89 V) compared to commercial Pt/C. The Zn-air battery (ZAB) assembled with FeNxPCs reveals excellent battery performance, including a high open circuit voltage of 1.50 V, peak power density of 155.4 mW cm−2, and cycling stability with 500 cycles. The excellent ORR activity of FeNxPCs could be ascribed to the porous structure, Fe–Nx active sites, and high defect level of FeNxPCs. This strategy can modulate 3D porous structure via self-template synthesis, which provides a novel insight for development of high-performance air cathode catalyst.