Heterostructured cobalt sulfides in N, S dual-doped hollow carbon spheres for high-performance rechargeable liquid and flexible Zn-air batteries

초록

Designing efficient, durable, and cost-effective bifunctional electrocatalysts is vital for advancing rechargeable Zn-air batteries (ZABs) toward practical applications. Herein, we report a high-performance electrocatalyst for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), consisting of uniformly dispersed Co9S8/CoS heterostructures embedded within nitrogen and sulfur co-doped hollow carbon spheres (Co9S8/CoS@NSC). The melamine-formaldehyde (MF)-derived hollow architecture maximizes the active surface area and enables efficient mass transport, while the well-defined Co9S8/CoS heterointerfaces promote rapid charge transfer and provide abundant defect sites for ORR and OER. The polypyrrole-derived carbon framework ensures structural stability during operation, and dual N, S doping effectively modulates the electronic structure for enhanced catalytic activity. Benefiting from these synergistic features, the Co9S8/CoS@NSC electrocatalyst delivers outstanding bifunctional catalytic performance, achieving an OER overpotential of 335 mV at 20 mA cm- 2 and an ORR half-wave potential of 0.838 V. When employed as an air cathode in both liquid and flexible ZABs, the catalyst exhibits high peak power densities of 172.19 mW cm- 2 and 74.9 mW cm- 2, respectively, surpassing that of precious metal-based ZAB. This work highlights the effectiveness of integrated structuralcompositional engineering and offers valuable guidance for designing next-generation electrocatalysts for high-performance, flexible, and wearable energy storage systems.

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