Reconstructed Monolithic RuNi Heterostructure Enables Hydrogen Production from Alkaline Seawater at Industrial Current Density.

Industrial-scale hydrogen production requires electrocatalysts capable of simultaneously delivering high activity, long-term durability, and seawater compatibility. In this work, a monolithic RuNiOx catalyst directly grown on Ni foam is reported, which evolves into the Ru/NiO heterostructure during operation. The reconstructed electrocatalyst presents excellent catalytic performance with a mass activity of 0.47 A mg-1 Ru at an overpotential of 50 mV, twice that of the benchmarked Pt/C (0.21 A mg-1 Pt) and remarkable durability of over 350 h at 1 A cm-2 without noticeable degradation. Even in harsh alkaline seawater, the electrode maintains stable operation for 100 h at both 100 and 500 mA cm-2, and functions reliably at 65 °C under industrial conditions. In situ spectroscopic and computational results reveal that RuO2 is dynamically reduced to metallic Ru while NiO remains stable, thereby forming robust Ru/NiO interfaces as the real active site. This study demonstrates an effective strategy for designing high-performance electrodes suitable for industrial-scale seawater electrolysis.