Enhanced activity towards oxygen electrocatalysis for rechargeable Zn–air batteries by alloying Fe and Co in N-doped carbon

Abstract

Large-scale application of rechargeable Zn–air batteries requires low-cost electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as alternatives to noble metals. Herein, FeCo nanoparticles embedded in N-doped carbon (FeCo/N–C) were prepared by a two-step pyrolysis route. FeCo/N–C exhibits excellent activities toward both the ORR (half-wave potential of 0.84 V) and OER (overpotential of 345 mV at 10 mA cm⁻²), which are comparable to those of commercial Pt/C and RuO₂, and by far exceeding their counterparts Fe/N–C and Co/N–C. Furthermore, the FeCo/N–C catalyst was evaluated in a rechargeable Zn–air battery for the full-cell test. The FeCo/N–C based battery is more durable with a smaller round-trip overpotential after 800 cycles than the battery using an expensive Pt/C + RuO₂ mixture catalyst.