Durable Alkaline Seawater Electrolysis through the Synergistic Effect of Crystalline-Amorphous Interface Coupling of Ferrocene-Based MOF/NiOOH.

Seawater electrolysis offers a sustainable and eco-friendly route for hydrogen production, with advantages of zero carbon emissions and reduced reliance on freshwater. However, the presence of impurity ions, especially Cl, imposes strict requirements on electrocatalysts in terms of activity and corrosion resistance, which limits large-scale application. In this work, the crystalline-amorphous (c-a) interface engineering offers a promising pathway to overcome this trade-off. The c-a heterojunction catalyst grown on nickel foam (FcNi-BDC-aNiOOH/NF) is constructed via integrating two-dimensional ferrocene-based metal-organic frameworks (FcNi-BDC) with amorphous nickel oxyhydroxide (aNiOOH). This interface induces dynamic charge redistribution, forming a type-II heterojunction with a built-in electric field that drives directional charge separation and suppresses the electron-hole recombination. This interfacial synergy elevates Ni content and optimizes the adsorption free energy of *OOH intermediates ΔG⁎ = 1.22 eV, while the amorphous phase dynamically passivates surface defects under chloride-rich conditions. As a result, FcNi-BDC-aNiOOH/NF achieves an ultralow oxygen evolution reaction (OER) overpotential of 329 mV at 1000 mA cm in alkaline seawater, along with exceptional stability (89% retention after 400 h at 500 mA cm) and chloride corrosion resistance (corrosion current density of 26 μA cm). This work elucidates atomic-scale interactions across the c-a interface and provides a universal strategy for developing robust electrocatalysts for large-scale seawater electrolysis and sustainable hydrogen production.