Unidirectional competitive redox enabled unsegmented natural sea-water splitting for green hydrogen production

Abstract

Sea-water electrolysis presents electrochemical complexities due to the concurrent chlorine evolution reaction (CER) and subsequent fuel contamination, which traditionally demand segmented cell architecture with expensive membranes and dimensionally stable precious metal anodes. By inducing a unidirectional competitive redox, we demonstrate membrane-free, scalable green hydrogen production from natural sea-water without using any precious metals. The oxidized form of the competitive redox species is stable on a carbon electrode making it effectively a unidirectional redox, which effectively counteracts the parasitic CER and simultaneously aids hydrogen evolution by releasing additional protons. This approach in a lab-level prototype yields an unsegmented precious metal-free natural sea-water electrolyzer that operates at a voltage as low as 1 V, producing green hydrogen for 100 hours with energy consumption nearly one-third that of conventional methods. This offers an energy-efficient pathway for centralized green hydrogen production without any fuel purifier, which is crucial for climate stabilization efforts.