ZIF-67-derived Co nanoparticles anchored in N doped hollow carbon nanofibers as bifunctional oxygen electrocatalysts

Developing highly active and robust bifunctional non-precious oxygen electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is of paramount importance for enhancing the efficiency of zinc-air battery. Herein, Co nanoparticles anchored in N doped hollow and porous carbon nanofibers (CoN-HPCNF) are obtained via an in-situ growth-pyrolysis approach with the hybrid of ZIF-67 and carbon nanofibers as the precursor. Originating from its high surface area, firm and hierarchical porous structure, effective doping of N as well as synergistic effect from Co nanoparticles and HPCNF, the optimized CoN-HPCNF shows prominent bifunctional catalytic activity and long-term stability toward OER and ORR. Importantly, the assembled aqueous zinc-air battery with the prepared catalyst as the air cathode delivers a peak power density of 126.6 mW cm−2 and narrow charge-discharge voltage gap together with excellent operation durability (more than 280 h at the current density of 5 mA cm−2), outdoing the commercial precious metal catalysts (Pt/C + IrO2).