F‐Mediated Precise Control Over Amorphous/Crystalline Fe/Ni‐Based Phosphides Heterostructure for Efficient Oxygen Evolution Reaction

ABSTRACT Transition metal‐based amorphous/crystalline (a/c) heterostructured catalysts have garnered significant attention due to their exceptional activity, stability, and cost‐effectiveness. However, the precise synergistic regulation of interfacial composition and phase states remains challenging. Herein, we propose an innovative strategy for the controllable synthesis of a/c heterostructures using MIL‐100(Mn) template. By leveraging the intrinsic coordination disparity between Ni 2+ and Fe 3+ to drive phase separation, combined with F − mediated ion exchange‐phosphidation synergy, we successfully constructed an amorphous FeP x /crystalline Ni 2 P heterostructure (a‐(F, Fe)P x /Ni 2 P) with precise compositional control. Systematic investigations reveal that F − not only enhances metal ion exchange through complex stabilization but also induces amorphous/crystalline phase separation via electronic modulation. Meanwhile, a deep reconstruction process occurs under high voltage, transforming the catalyst into active F‐Fe/NiOOH species, which further enhances the catalytic activity and durability. Benefiting from the synergistic effects of heterointerface electronic coupling and deep reconstruction, the as‐prepared a‐(F, Fe)P x /Ni 2 P catalyst exhibits exceptional oxygen evolution reaction (OER) performance in 1 M KOH, delivering an ultralow overpotential of 278 mV at 30 mA cm −2 and maintaining excellent stability over 100 h with negligible degradation. This work establishes a novel “coordination difference‐driven, fluorine‐mediated” interface engineering strategy, offering valuable insights for the rational design of high‐performance heterostructured electrocatalysts.