Carbon-integrated NiCoFe nanodomains from PBAs enabling electrochemically induced oxyhydroxide reconstruction and high OER activity

초록

Developing robust and earth-abundant oxygen electrocatalysts requires simultaneous control over morphology, electronic structure, and interfacial transport. We present a leach–coat–pyrolyze strategy that transforms NiCoFe Prussian blue analogue (PBA) nanocubes into NiCoFe nanodomains uniformly embedded within an N-doped carbon matrix (NiCoFe–ND@NC). Selective Fe leaching yields hollow, mesoporous cubes while preserving the overall framework. After conformal PDA coating and controlled pyrolysis, the cubes convert to Ni–Co–Fe metallic/oxide nanodomains intimately interfaced with N-doped carbon, establishing electronic pathways. SEM/TEM show hollow, roughened shells of nanosized domains, and STEM-EDS indicates uniform Ni/Co and N/C enrichment throughout the structure. XRD shows loss of PBA order after pyrolysis, while Raman reveals defect-rich turbostratic carbon (D/G bands). XPS shows mixed Ni/Co states with pyridinic/graphitic N and hydroxyl-rich surfaces; O 1 s variations mainly reflect hydroxyl/adsorbate evolution rather than extensive oxygen-vacancy formation. This integrated architecture lowers charge-transfer resistance and increases accessible surface area, enabling OER with an overpotential of 249 mV at 10 mA cm−2 and a Tafel slope of 50.9 mV dec−1. In rechargeable Zn–air batteries, it delivers an open-circuit potential of 1.47 V, ∼179 mW cm − 2 peak power density, and stable cycling over 24 h. This modular strategy provides a useful design platform for PBA-derived hybrids, where multimetallic nanodomains coupled with N-doped carbon are capable of evolving into oxyhydroxide-like active surfaces for efficient oxygen electrocatalysis.

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