Coupling N-doped biomass-derived carbon and interface of FeP4/Fe3O4 for high-performance rechargeable zinc-air batteries

Developing cost-effective and efficient bifunctional oxygen electrocatalysts remains a critical challenge for advancing rechargeable Zn-air batteries (ZABs). Here, a novel bifunctional oxygen electrocatalyst, FeP 4 /Fe 3 O 4 @NWC, was obtained by coupling N-doped biomass-derived carbon and interface of FeP 4 /Fe 3 O 4 through electric field-induced deposit and pyrolytic phosphorus conversion. This catalyst exhibits exceptional bifunctional performance with a low oxygen reduction/evolution reaction potential gap (Δ E  = 0.61 V), surpassing commercial Pt/C and RuO 2 . The rechargeable ZABs based on FeP 4 /Fe 3 O 4 @NWC as cathode catalyst achieve a high open-circuit voltage (1.496 V), peak power density (185 mW cm −2 ), and long-term stability (290 h). Quasi-solid-state ZABs further demonstrate 66 h of stable cycling and a specific capacity of 747.6 mAh g Zn −1 . The biomass-derived 3D (three-dimensional) carbon matrix with hierarchical porous architecture assures high stability, excellent conductivity and high exposure of active sites for catalyst. The synergistic effect of FeP 4 and Fe 3 O 4 optimizes charge transfer and reaction kinetics for oxygen electric reaction. The coupling N-doped carbon and interface of FeP 4 /Fe 3 O 4 regulates electronic structure of active sites and optimizes activation energy of reactants to enhance bifunctional oxygen electrocatalytic activity. This work proposes a novel strategy for designing high performance biomass-derived bifunctional oxygen electrocatalysts by creating interface of transition metal composites and coupling it with N-doped carbon to offer a promising pathway for next-generation energy storage technologies.