Facile Construction of Self-Supported Ru-Ni(OH)2 with Built-In Interfacial Electric Field for Accelerating Hydrogen Evolution

• • Ru-Ni(OH)2/NF achieves a record-low HER overpotential of 9.6 mV at 10 mA cm−2 in alkaline media, outperforming Pt/C and most reported catalysts, directly addressing the kinetic bottleneck of water dissociation. • • The catalyst exhibits an exceptionally low potential of 0.015 V vs. RHE for hydrazine oxidation at 100 mA cm−2, enabling energy-efficient hydrogen production coupled with hydrazine degradation. • • The overall hydrazine splitting (OHzS) system requires only 0.09 V to deliver 50 mA cm−2, which is 1.637 V lower than overall water splitting, representing a significant reduction in energy input for hydrogen generation. • • Chronoamperometry shows negligible current decay at 30 mA cm−2 over 30 hours, with SEM and XPS confirming structural stability, indicating robust long-term operation for industrial applications.