γ-CD-MOF-derived heterostructures as bifunctional electrocatalysts for rechargeable zinc–air batteries

Abstract

The development of efficient and cost-effective bifunctional electrocatalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is promising for high-performance rechargeable metal–air batteries. In this work, a Co–N,O–C@C₃N₄ heterostructure catalyst is synthesized via molten salt-assisted pyrolysis of a mixture of cobalt loaded γ-cyclodextrin MOFs and melamine. Benefitting from the synergy of Co–N,O–C and C₃N₄ in regulating the electrochemical structure, optimized activity is recorded at a current density of 10 mA cm⁻² with an overpotential at 290 mV for the OER, and a half-wave potential of 0.84 V for the ORR. Moreover, a rechargeable Zn–air battery with Co–N,O–C@C₃N₄ as an air electrode exhibits a large open-circuit voltage (1.43 V) with a high peak power density (112 mW cm⁻²) and long cycle life (over 200 cycles). Therefore, this work provides a new vision for the design and preparation of promising functional electrocatalysts for Zn–air batteries.