A strongly cooperative spinel nanohybrid as an efficient bifunctional oxygen electrocatalyst for oxygen reduction reaction and oxygen evolution reaction

The development of efficient, stable and low-cost bifunctional oxygen electrocatalysts is critical to the realization of practically viable rechargeable Zn-air batteries. Herein, we report a strongly cooperative spinel nanohybrid as a promising air electrode catalyst for rechargeable Zn-air batteries. Ultrafine sub-10 nm MnFe2O4 crystals are in situ grown on the ultrathin NiCo2O4 nanosheets, leading to a highly effective surface area and a strong synergistic chemical coupling effect. The distinct architecture and complex composition endow an excellent bifunctional oxygen electrocatalytic activity in alkaline condition. The practical rechargeable Zn-air battery with the hybrid electrocatalyst demonstrates a high round-trip efficiency (a low discharge-charge voltage gap of 0.81 V at a reversible current density of 10 mA cm−2) and an outstanding durability, which outperforms the commercial Pt/Ru/C electrocatalyst. The resulting hybrid (MnFe2O4/NiCo2O4) shows great promise as an alternative bifunctional electrocatalyst to the precious metals for the application in Zn-air batteries.