Synthesis of Fe₂O₃ nanoparticle-decorated N-doped reduced graphene oxide as an effective catalyst for Zn-air batteries

Abstract

The advancement of Zn-air batteries requires effective and inexpensive electrocatalysts that facilitate the oxygen reduction reaction (ORR) and evolution reaction (OER). Herein, we report an effective electrocatalyst of Fe2O3 nanoparticle-decorated N-doped reduced graphene oxide (Fe2O3/N-rGO), in which porous Fe2O3 nanoparticles of ∼37 nm are anchored on the N-rGO surface uniformly. In an alkaline solution, the synthesized Fe2O3/N-rGO affords superior ORR and OER activity in comparison with Fe2O3 and N-rGO, demonstrating the reinforced synergistic effect. Moreover, it exhibits a comparable limiting current density and a higher current retention ratio in the ORR than commercial Pt/C. A Zn-air battery with Fe2O3/N-rGO delivers a peak power density of 80.1 mW cm−2, and the energy density reaches 730.2 Wh kgZn−1. In addition, stable voltage gaps of ∼0.91 V during discharge and charge are achieved at 5 mA cm−2, and the energy efficiency is maintained at ∼60% over 120 cycles, illustrating the remarkable stability for rechargeable Zn-air batteries.