Ultra-low voltage hydrazine splitting with pulsed laser harnessed Ir/CoP for efficient Zn-hydrazine battery systems

Abstract

Hydrazine-assisted water splitting presents a capable low-voltage, energy-effective approach to green hydrogen production while addressing hydrazine pollution concerns. Herein, an iridium-decorated CoP nanostructure (Ir/CoP) is designed and synthesized as an advanced bifunctional electrocatalyst for both the anodic hydrazine oxidation reaction (HzOR) and the cathodic hydrogen evolution reaction (HER). The Ir/CoP-3 catalyst exhibits superior hydrazine electrooxidation with minimal overpotential and enhanced mass activity, alongside improved HER performance. Electrochemical characterization demonstrates that the Ir/CoP-3 catalyst achieves an exceptionally low HER overpotential of 102 mV and an ultralow HzOR operating potential of −14 mV at 10 mA cm−2. Additionally, density functional theory calculations provide deep insights into the bifunctional catalytic activity of the Ir/CoP catalyst. Consequently, the overall hydrazine splitting (OHzS) electrolyzer, configured with Ir/CoP-3(−)||Ir/CoP-3(+), operates at a minimal cell voltage of only 0.125 V at 10 mA cm−2. Remarkably, incorporating the Ir/CoP-3 catalyst as the cathode with a Zn foil anode in a Zn–hydrazine (Zn–Hz) battery delivers a high energy efficiency of 92 % and outstanding cyclic stability. Moreover, self-sustained hydrogen generation is achieved by coupling the Zn–Hz battery with the OHzS electrolyzer, underscoring its strong potential for practical applications.