Energy-efficient electrochemical hydrogen production from seawater: a review of chemical-assisted splitting technologies

Seawater splitting has been considered an efficient technique for producing ultrapure and clean hydrogen. However, its large-scale production is limited by slow kinetics and the generation of undesirable, highly corrosive Cl₂/hypochlorite products. A revolutionary technique for generating hydrogen and valuable products involves replacing the CER/OER with thermodynamically more beneficial electro-oxidation reactions. These electro-oxidation reactions, which affect the loss of electrons at the anode, are more thermodynamically favorable than the conventional CER/OER. This strategy also includes other functionalities such as electro-synthesis (formic acid, acetone), electro-degradation of toxic chemicals (hydrazine and urea sewage), crystalline NaCl production by inhibiting chlorine-related competitive processes (by introducing the common-ion effect), and increasing electrocatalyst durability by reducing the generation of toxic products (Cl₂/hypochlorite). This review explores new paradigms in energy-efficient hydrogen production via chemical-assisted electrocatalytic seawater splitting, focusing on challenges in seawater splitting, reductive chemical selection, advancements in electrocatalysts, and related electrochemical reaction mechanisms. To our knowledge, this will be the latest review on chemical-assisted energy-saving seawater splitting for hydrogen production.