Reconstruction of NiCu Hydroxide-Organic Frameworks into Active Oxyhydroxides Enables Industrial-Grade Seawater...

Efficient and durable electrocatalysts for direct seawater electrolysis are essential for sustainable hydrogen production but are limited by sluggish oxygen evolution kinetics and chloride-induced degradation. Here, we report a reconstruction-engineered catalyst based on bimetallic hydroxide-organic framework microbulk arrays, where controlled Cu incorporation (NiCu-MHOF-10, 10% Cu) modulates the electronic structure of Ni sites. The optimized NiCu-MHOF-10 achieves industrially relevant current densities of 1 A cm^-2 at low overpotentials of 480, 430, and 492 mV in freshwater, simulated seawater, and natural seawater, respectively. In a two-electrode system, a NiCu-MHOF-10 (+)//Pt/C (-) electrolyzer achieves 0.6 A cm^-2 at 1.84 V (80 °C) with negligible decay over 200 h at 150 mA cm^-2. Operando analyses reveal in situ reconstruction into high-valent γ-NiOOH as the true active phase. Cu incorporation accelerates intrinsic kinetics and stabilizes the oxyhydroxide phase against chloride corrosion, offering a viable strategy for industrial seawater electrolysis.