Pulsed laser-tuned ruthenium@carbon interface for self-powered hydrogen production via zinc–hydrazine battery coupled hybrid electrolysis

Herein, we report the synthesis of selectively face-centered cubic structured ruthenium nanospheres covered in graphitic carbon (denoted as Ru@C) using an effective and innovative pulsed laser ablation in liquid strategy. The Ru@C‒200 catalyst exhibited a low overpotential of 48 ​mV for hydrogen evolution reaction (HER) and an ultralow oxidation potential of −8 ​mV (vs. reversible hydrogen electrode) for hydrazine oxidation reaction (HzOR) at 10 ​mA ​cm−2, maintaining long-term durability for over 100 ​h, demonstrating its dual-functional activity. This performance was attributed to the robust synergistic coupling between the Ru core and C shell, as confirmed by in situ electrochemical studies and density functional theory investigations. As a result, overall hydrazine splitting (OHzS) in the Ru@C‒200||Ru@C‒200 system requires only low cell voltages of 0.11 and 0.70 ​V at 10 and 100 ​mA ​cm−2, respectively. Moreover, a rechargeable zinc–hydrazine (Zn–Hz) battery, fabricated using the Ru@C‒200 catalyst as the cathode and Zn foil as the anode, exhibited a high energy efficiency of 90% and efficient H2 production, validating its remarkable ability for practical applications. Notably, coupling Zn–Hz battery with OHzS system encourages self-powered H2 production. This study provides potential guidance for engineering robust electrocatalysts for large-scale H2 production while purifying hydrazine-containing industrial sewage.