Bimetallic Sulfides Embedded in a Boron Modulated Carbon Matrix as the Bifunctional Catalyst with a Low Oxygen Evolution Reaction Overpotential for an Advanced Zinc-Air Battery

A composite bifunctional catalyst (FeNiS-NBC/C) was prepared with iron nickel sulfide nanoparticles embedded in a hybrid carbon matrix. The unique introduction of the boron element modulated the structure in achieving an ultralow oxygen evolution reaction (OER) overpotential. The incorporation of cellulose in the synthesis has improved the oxygen reduction reaction (ORR) performance. In the two-step synthesized FeNiS-NBC/C, a mixed transport network formed, with enhanced heterostructures and abundant catalytic sites. FeNiS-NBC/C exhibits the OER overpotential of 216 mV at the current density of 10 mA cm–2, as well as with the excellent ORR performance. The low OER overpotential reduces the oxidation corrosion in the rechargeable zinc-air batteries. The zinc-air battery with a liquid electrolyte assembled using FeNiS-NBC/C exhibited the power density of 133.0 mW cm–2 and specific capacity of 797.8 mAh g–1. The solid-state zinc-air battery assembled using FeNiS-NBC/C exhibited the power density of 61.4 mW cm–2 and can be stably charge–discharge cycled for 46 h. This work pointed out a novel avenue to construct bifunctional catalysts in the future for advanced zinc-air batteries.