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

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 RuO 2 , 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 + RuO 2 mixture catalyst. The synergy of FeCo alloys in N-doped carbon achieves outstanding bifunctional activity of the ORR and OER, which endows Zn-air batteries with better cycling performance than noble-metal benchmarks.