Lattice‐Confined Ru Clusters Driving Efficient Hydrazine‐Assisted Membrane‐Free Hydrogen Production

Abstract The inherent trade‐off between stable anchoring of metal clusters and sufficient exposure of active sites in supported metal catalysts critically limits their electrocatalytic efficiency. This study overcomes this limitation by synthesizing Ru clusters partially confined within the SnO 2 lattice (Ru@SnO 2 ) via a molten salt‐assisted approach. This unique structure synergistically integrates strong metal‐support interaction (SMSI) with high active site exposure. The resulting catalyst exhibits exceptional bifunctional activity in alkaline media, achieving remarkably low overpotentials of 9 mV for the hydrogen evolution reaction (HER) and −82 mV for the hydrazine oxidation reaction (HzOR) at 10 mA cm −2 . A two‐electrode system utilizing this catalyst demonstrated stable operation for 1000 h. Integrated into a membrane‐free electrolysis (MFE) system for HzOR‐assisted hydrogen production, it requires only 0.877 V to deliver 1.0 A cm −2 , achieving a substantial 67.8% energy saving compared to conventional anion exchange membrane (AEM) electrolyzers (2.726 V). Theoretical studies reveal that lattice confinement downshifts the Ru d‐band center to optimize hydrogen adsorption energy. A pronounced work function difference generates a built‐in electric field that accelerates water dissociation, while an end‐on bidentate N 2 H 4 adsorption configuration enhances HzOR activation efficiency.