Tailoring Coordination and Pore Structure of MOF-Derived Co Single-Atom Catalysts Anchored on Graphene for Rechargeable Zinc–Air Batteries

초록

Achieving high-performance single-atom catalysts (SACs) for rechargeable Zn–air batteries (ZABs) requires simultaneous optimization of pore structure and coordination environment. However, MOF-derived SACs typically feature micropore-dominated carbon frameworks and planar coordination symmetry, restricting oxygen diffusion and intrinsic activity. Here, we introduce a dual-engineering strategy that combines polymer encapsulation with wavy graphene oxide (GO) substrates. Bimetallic Co/Zn zeolitic imidazole framework (Co-ZIF-8) precursors were coated with polyvinylpyrrolidone (PVP) and assembled on GO, followed by pyrolysis to yield CoSA@P-NC/rGO. The PVP layer induced mesopores via controlled shrinkage of the ZIF structure, while the wavy GO substrate modulated the coordination environment of atomically dispersed Co─Nx sites, extending bond lengths and introducing symmetry distortion. Benefiting from these structural and electronic features, CoSA@P-NC/rGO exhibited outstanding bifunctional activity, with a half-wave potential of 0.90 V for oxygen reduction reaction and a low overpotential of 397 mV at 10 mA cm−2 for oxygen evolution reaction. When employed as a ZAB cathode, it achieved a high power density of 190 mW cm−2, a specific capacity of 832 mA h g−1, and durable cycling over 600 cycles. This synergistic strategy of pore and coordination engineering provides a promising platform for developing efficient, long-lived SACs for energy storage applications.

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