Phytic Acid‐Assisted Phase Reconstruction for Co‐Co ₂ P Heterojunction/Carbon Nanotube Oxygen Electrocatalysts for Rechargeable Zinc‐Air Batteries

ABSTRACT Rechargeable zinc‐air batteries (RZABs) have high theoretical energy density but face practical limits from slow oxygen reduction/evolution reactions (ORR/OER) at air cathodes. Herein, a novel strategy integrating dual‐coordination‐directed growth and in situ phase reconstruction to synthesize heterostructured Co‐Co ₂ P embedded in N, P‐codoped carbon nanotubes (CNTs). The melamine‐PEG‐phytic acid nanosheets serve as multifunctional sources for simultaneous carbonization, N doping, and phosphorus incorporation. Using coordination polymers as precursors, controlled CNT growth and precise modulation of phytic acid concentration/calcination temperature enable phase‐selective reconstruction of metallic Co and semiconducting Co ₂ P, forming heterointerfaces with built‐in electric fields. X‐ray absorption spectroscopy and DFT calculations reveal that interfacial charge redistribution of the CNT warped Co‐ Co ₂ P heterojunction creates electron‐enriched Co ₂ P surfaces for enhanced O ₂ adsorption, while positively charged Co sites accelerate OH ⁻ oxidation kinetics. The optimized Co‐Co ₂ P@CNT catalyst shows superior bifunctional activity, achieving an OER overpotential of 1.61 V and an ORR half‐wave potential of 0.86 V 0.1 m KOH; the assembled RZAB delivers a peak power density of 192 mW cm ⁻² and sustains stable cycling for 1193 h with minimal voltage decay. This work establishes a universal coordination‐competition method for designing heterogeneous structured materials, offering new insights for advanced energy conversion systems.