Bio-derived FeNi alloy confined in N-doped carbon nanosheets as efficient air electrodes for Zn–air battery

It is imperative to design and manufacture electrocatalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for popularization of rechargeable Zn-air batteries. Herein, FeNi alloy confined in N-doped carbon nanosheets (FeNi@NCSs) was harvested via a facile complexation-pyrolysis strategy from the mixture of guanine and metal chlorides. After strictly exploring the pyrolysis temperature and metal types, the resulted FeNi@NCSs showed greatly improved performances on both the ORR (onset potential of 0.93 V and half-wave potential of 0.84 V) and OER (overpotential of 318 mV at 10 mA cm-2 and 379 mV at 100 mA cm-2). Further, the FeNi@NCSs based Zn-air battery exhibited a higher open circuit voltage (1.496 V), a larger power density (128.8 mW cm-2), and prominent durability (360 cycles, 120 h). This study provides an appealing approach to utilize biomass for synthesis of low-cost and high-efficiency electrocatalysts in energy associated systems.