Long‐Lasting Hybrid Seawater Electrolysis Enabled by Anodic Mass Transport Intensification for Energy‐Saving Hydrogen Production

Abstract Hybrid water electrolysis offers a groundbreaking approach to energy‐saving hydrogen production by utilizing thermodynamically favorable and value‐added reactions to replace sluggish anodic oxygen evolution in overall water splitting. However, numerous anodic processes generate intermediates or products incompatible with aqueous environments, thereby degrading anodic performance to limit the efficiency and durability of hybrid water electrolysis. Herein, this difficulty is addressed by applying anodic mass transport intensification in conjunction with catalyst engineering, realizing a long‐lasting hybrid seawater electrolysis coupling sulfion oxidation reaction (SOR) for efficient hydrogen production below 1.2 V at an industrial‐level current density of 500 mA cm −2 . An exceptional longevity of 2000 h is achieved for the electrolysis by eliminating anode passivation by sulfur deposition during SOR, a general concern in the sulfur‐involved industrial sector. This technology cut the electricity expense of hydrogen production to 2.80 kWh m −3 H 2 , undercutting alkaline water electrolysis by 34.9–51.1%. Simultaneously, fast upcycling of sulfion pollutants to value‐added sulfur is achieved to add additional economic and environmental profits, enabling hydrogen production at a midpoint expense ($ 0.93) of the United States Department of Energy's 2026 target ($ 2.0) for the cost per gallon of gasoline‐equivalent.