Hollow Schottky Heterostructures for Highly Efficient Bifunctional Oxygen Electrocatalysis in Zinc-Air Batteries

With advantages such as high theoretical energy density and eco-friendly operation, rechargeable zinc-air batteries (RZABs) have gained considerable interest as viable systems for future sustainable energy storage. Nevertheless, achieving high efficiency and long-term stability in bifunctional electrocatalysts that can simultaneously drive the oxygen reduction and evolution reactions remains a significant obstacle. In this work, we report the rationally designed hollow FeCo/CoFe2O4 heterostructure (H–FeCo/FeCoO) as a high-performance bifunctional electrocatalyst for RZABs, in which the interconnected hollow architectures and well-defined Schottky interfaces are built via a polystyrene sphere-assisted strategy. The obtained H–FeCo/FeCoO bifunctional catalysts exhibit high activities for both ORR and OER, with a narrow voltage gap (ΔE) of 660 mV, outperforming that of the Pt/C + RuO2 benchmark. The as-assembled RZAB delivers a remarkable power density of 310 mW cm–2, and demonstrates excellent operational stability exceeding 500 h. Based on the DFT calculations, the rate-determining steps in ORR/OER processes and valence electron distributions in H–FeCo/FeCoO have been demonstrated, unveiling the origins of boosted catalytic activity and accelerated oxygen delivery. Current work presents a compelling design strategy for exploring advanced bifunctional catalysts with improved mass transport and electrochemical activity/durability for next-generation energy storage devices.