Active Site Implantation for Ni(OH)₂ Nanowire Network Achieves Superior Hybrid Seawater Electrolysis at 1 A cm⁻² with Record‐Low Cell Voltage

Direct seawater electrolysis provides a grand blueprint for green hydrogen (H2) technology, while the high energy consumption has severely hindered its industrialization. Herein, a promising active site implantation strategy is reported for Ni(OH)2 nanowire network electrode on nickel foam substrate by Ru doping (denoted as RuNi(OH)2 NW2/NF), which can act as a dual-function catalyst for hydrazine oxidation and hydrogen evolution, achieving an ultralow working potential of 114.6 mV to reach 1000 mA cm−2 and a small overpotential of 30 mV at 10 mA cm−2, respectively. Importantly, using the two-electrode hydrazine oxidation assisted seawater electrolysis, it can drive a large current density of 500 mA cm−2 at 0.736 V with over 200 h stability. To demonstrate the practicability, a home-made flow electrolyzer is constructed, which can realize the industry-level rate of 1 A cm−2 with a record-low voltage of 1.051 V. Theoretical calculations reveal that the Ru doping activates Ni(OH)2 by upgrading d-band centers, which raises anti-bonding energy states and thus strengthens the interaction between adsorbates and catalysts. This study not only provides a novel rationale for catalyst design, but also proposes a feasible strategy for direct alkaline seawater splitting toward sustainable, yet energy-saving H2 production.