Energy-saving hydrogen generation enabled by boosted hydrazine oxidation over hierarchical Co/Ru–RuPx interfaces

The efficiency and sustainability of water splitting for green hydrogen production are often hindered by the limited performance of electrocatalysts and the sluggish kinetics of the anodic oxygen evolution reaction (OER). To overcome these challenges, this study reports a laser-engineered cobalt-integrated Ru–RuPx (Co/Ru–RuPx) electrocatalyst with a hierarchical architecture for hydrazine-assisted water splitting. The optimized Co(4)/Ru–RuPx catalyst, with Co:Ru–RuPx ratio of 4:1, exhibits remarkable activity toward the hydrazine oxidation reaction (HzOR), requiring an ultra-low potential of 49 mV versus reversible hydrogen electrode (RHE) at 10 mA cm−2, significantly outperforming the benchmark IrO2 catalyst. Furthermore, an overall hydrazine splitting employing a Pt/C||Co(4)/Ru–RuPx achieves a cell voltage as low as 0.152 V at 10 mA cm−2, yielding substantial energy savings (ΔE≈1.48 V) compared to conventional water electrolysis, which demands 1.638 V at 10 mA cm−2. In situ Raman spectroscopy reveals the formation of key intermediates on the surface of the Co(4)/Ru–RuPx catalyst during the HzOR dehydrogenation pathway. Complementary density functional theory (DFT) calculations reveal that the Co/Ru–RuPx catalyst exhibits enhanced interfacial electronic structure, favorable d-band center alignment, and significant charge redistribution across Co, Ru, and RuP2 sites. These features promote strong adsorption and activation of N2H4, leading to a low energy barrier of 0.31 eV for the rate-determining step and thereby boosting HzOR activity. This work highlights that the synthesized cobalt-modified Ru–RuPx is an efficient electrocatalyst for energy-efficient clean hydrogen technologies.