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

In situ grown monolithic RuNiOx on nickel foam is reconstructed under cathodic conditions to yield a robust Ru/NiO heterointerface. This evolution optimized the surface hydrophilic‐aerophobic properties and tuned the adsorption affinity for key intermediates, thus delivering exceptional activity and durability for the hydrogen evolution reaction in alkaline seawater at industrial current densities. Abstract 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−1Ru at an overpotential of 50 mV, twice that of the benchmarked Pt/C (0.21 A mg−1Pt) 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. In situ grown monolithic RuNiO x on nickel foam is reconstructed under cathodic conditions to yield a robust Ru/NiO heterointerface. This evolution optimized the surface hydrophilic-aerophobic properties and tuned the adsorption affinity for key intermediates, thus delivering exceptional activity and durability for the hydrogen evolution reaction in alkaline seawater at industrial current densities. Abstract Industrial-scale hydrogen production requires electrocatalysts capable of simultaneously delivering high activity, long-term durability, and seawater compatibility. In this work, a monolithic RuNiO x 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 RuO 2 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. Advanced Science, Volume 12, Issue 48, December 29, 2025.