Tailored Interfacial Coupling in CoPi/PANI@Nickel‐Cobalt Phosphide Heterostructure Electrocatalysts for Enhanced Hydrogen Evolution in Alkaline Media

Interface engineering and electronic modulation are key strategies for developing efficient and durable electrocatalysts for sustainable hydrogen production. Herein, we report a hybrid electrocatalyst prepared by integrating cobalt phosphate (CoPi) and polyaniline (PANI) onto a nickel cobalt phosphide (NiCoP) matrix to enhance the alkaline hydrogen evolution reaction (HER). Co­‐N coordination was confirmed by XPS analysis, while density of states analysis revealed an upward shift in the Co d‐band center from −1.11 to −1.03 eV following hybridization. This electronic modulation facilitated rapid charge transfer and strengthened interfacial electronic coupling, thereby accelerating HER kinetics through the conductive PANI framework. As a result, the CoPi/PANI@nickel‐cobalt phosphide heterostructure delivers a low overpotential of 115 mV at 10 mA cm ^{‒ 2} and a Tafel slope of 123.85 mV dec ^{‒ 1} , following the Volmer–Heyrovsky mechanism for efficient H ₂ O dissociation and (H*) adsorption. The catalyst also demonstrates long‐term electrochemical durability in alkaline media. This study highlights a versatile and scalable approach for designing multifunctional heterostructure electrocatalysts through polymer­–assisted interface modulation for sustainable hydrogen generation.