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 and 379 mV at 100 mA cm). 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), 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.