Synergistic W/Zn Co-Doped NiFe Layered Double Hydroxide (LDH)/Ni2P Nanosheet Electrocatalyst for High-Current-Density Overall Water Splitting With Enhanced Hydrogen/Oxygen Evolution Reaction (HER/OER) Performance and Long-Term Stability.

Developing electrocatalysts with high efficiency and long-term stability at industrial current densities remains a major challenge for practical water electrolysis. Here, we report a hierarchically ordered W-NiFe0.08ZnLDH/Ni2P/NCF electrocatalyst engineered through synergistic W/Zn co-doping and LDH/phosphide interfacial design. X-ray photoelectron spectroscopy reveals that W/Zn incorporation induces a 0.5 eV negative shift in the Ni 2p binding energy, increasing electron density at Ni sites while decreasing it at Fe sites and thereby optimizing the adsorption of Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) intermediates. Operando electrochemical impedance spectroscopy shows that the LDH/Ni2P heterojunction lowers charge-transfer resistance, promotes water dissociation, and shifts the HER rate-determining step toward the Heyrovsky process. During OER, the catalyst surface reconstructs into highly active β-NiOOH, as confirmed by HRTEM and SAED, enabling dynamic self-activation and enhanced durability. The catalyst requires only 130 mV for HER and 231 mV for OER at 500 mA/cm2. For overall water splitting, it delivers 1000 mA/cm2 at 1.95 V, outperforming the Pt/C||RuO2 benchmark. Moreover, it maintains stable operation for over 800 h at industrial current densities with minimal degradation. These results provide mechanistic guidance for designing durable, high-performance electrocatalysts for practical water electrolysis. This integrated strategy bridges activity, mechanistic understanding, and industrially relevant operational stability.