Co3Fe7 nanoparticles encapsulated in porous nitrogen-doped carbon nanofibers as bifunctional electrocatalysts for rechargeable zinc–air batteries

Abstract

Exploration of inexpensive and high-performance carbon-based electrocatalysts with abundant active sites for oxygen reduction and evolution reactions is vital for enhancing the performance of zinc–air batteries. Herein, well-dispersed Co₃Fe₇ nanoparticles encapsulated in porous nitrogen-doped carbon nanofibers (Co₃Fe₇-PCNF-850) are synthesized by employing polyvinylpyrrolidone (PVP) as the pore-forming agent via simple electrospinning and subsequent calcination. The resulting Co₃Fe₇-PCNF-850 with well-dispersed bimetal nanoparticles and a porous structure shows a half-wave potential of 0.85 V (vs. RHE) comparable to 20 wt% Pt/C for the oxygen reduction reaction, enhanced stability with negligible attenuation after 1000 cycles, high methanol resistance, and low overpotential for the oxygen evolution reaction. When Co₃Fe₇-PCNF-850 is employed as a cathode electrocatalyst, zinc–air batteries exhibit good cycling stability for 300 h and a high peak power density of 213 mW cm⁻² due to its excellent bifunctional catalytic activity. This work provides a simple strategy for the combination of hierarchically porous structures of carbon fibers with the optimized bifunctional activity of bimetal nanoparticles to improve battery performance.