Efficient hydrogen production by saline water electrolysis at high current densities without the interfering chlorine evolution

Abstract

Seawater electrolysis powered by renewable energy sources has been proposed to be a potentially cost-effective approach to green hydrogen production. However, the long-standing issue regarding the chlorine evolution reaction (CER) that deteriorates the performance of electrocatalysts and other components of electrolyzers has been impeding the market adoption of direct seawater electrolyzers. Herein, we demonstrate that coupling the cathodic hydrogen evolution reaction (HER) with the hydrazine oxidation reaction (HzOR) taking place at the anode enables the alkaline–saline water electrolysis to occur at a high current density without the unfavorable, interfering CER. Using bifunctional carbon paper supported Co–Ni–P nanowires (Co–Ni–P/CP) as the cathode and anode, we have accomplished hydrogen production in the alkaline–saline–hydrazine electrolyte at 500 mA cm⁻² with a small cell voltage of only 0.533 V and outstanding stability of 80 hours with minimal degradation.