Electronegativity‐Driven Heterointerfaces for Water Electrolysis: Thermodynamic and Kinetic Insights into Built‐In Charge Transfer

ABSTRACT Interfacial electronic modulation via heterostructure engineering puts forward a promising route toward effective water electrolysis. However, the mechanistic connection between atomic‐scale interface design, thermodynamic stability, and device‐level performance remains unresolved. Here, we report non‐noble nickel‐based heterostructures in which both systems outperform their pristine counterparts, defying the conventional unidirectional charge‐transfer paradigm. Electronegativity‐driven interfacial charge redistribution defines the activity order: NiV@NiCr‐LDH/NF > NiCr@NiV‐LDH/NF > NiV‐LDH/NF > NiCr‐LDH/NF. Guided by density functional theory and Pourbaix analysis, we identify surface‐functionalized oxygen species as the true catalytic termini, with metal centers acting as electronic modulators. The interfacial electronic structure lowers reaction barriers and drives dynamic Adsorbate‐mediated mechanism, as confirmed by operando impedance, temperature‐dependent, and pH‐dependent studies. The intrinsic activity is validated through multi‐normalized turnover frequency analysis, alongside ∼95.1% for hydrogen evolution reaction and 93% for oxygen evolution reaction Faradaic efficiency, indicating excellent selectivity. The optimized NiV@NiCr‐LDH/NF delivers low overpotentials (242 mV for OER and 144 mV for HER at 50 mA cm −2 ) and achieves ∼1.539 V at 10 mA cm −2 with 140 h stability. Importantly, these insights translate to practical systems, single‐stack anion exchange membrane water electrolyzer, seawater electrolysis, and solar and battery‐driven hydrogen production, offering a predictive framework for high‐activity, robust overall water electrolysis, and establishing a mechanistically grounded blueprint for scalable hydrogen generation.