In-situ construction of Co/CoSe Schottky heterojunction with interfacial electron redistribution to facilitate oxygen electrocatalysis bifunctionality for zinc-air batteries

Design of low-cost and high-performance bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a key topic in the development of zinc-air batteries. In this work, a facile in-situ partial reduction strategy is proposed to fabricate Co/CoSe Schottky junctions encapsulated in carbon (Co/ CoSe@NC). The heterojunction in the Co/CoSe@NC can tune Fermi level and charge redistribution to accelerate the charge transfer, while the metal-organic framework derived skeleton provides well-defined structure and abundant mesopores to facilitate mass transport. The accelerated charge transfer through the Mott-Schottky heterostructure can improve the intrinsic electrocatalytic activities for both electron-gaining ORR and electron-losing OER, which are confirmed by systematic characterizations and density functional theory calcu-lations. Furthermore, the Zn-air battery with the as-prepared Co/CoSe@NC heterojunction shows better per-formance than the Pt/RuO2-based counterpart, demonstrating good feasibility for practical applications.