Multiscale Design of Anion Exchange Membrane‐Based Seawater Electrolysis for Sustainable Hydrogen Production

ABSTRACT Growing demand for green hydrogen has intensified interest in seawater as an alternative feedstock to freshwater for large‐scale water electrolysis. However, direct seawater electrolysis remains challenging because chloride ions, multivalent cations, and dissolved impurities can induce parasitic reactions, corrosion, inorganic precipitation, membrane degradation, and interfacial instability. Anion exchange membrane‐based seawater electrolysis (AEMSWE) has emerged as a promising platform by combining alkaline electrochemistry with compact membrane‐based zero‐gap architectures, earth‐abundant catalysts, and potential scalability. Herein, we provide a comprehensive and critical overview of AEMSWE from fundamental seawater electrochemistry to device‐ and system‐level engineering. Emphasis is placed on oxygen evolution–chloride oxidation competition, which governs selectivity, efficiency, corrosion behavior, and durability. Recent advances in electrocatalysts, anion exchange membranes, ionomers, membrane–electrode assemblies, and cell/stack architectures are discussed with focus on mechanistic roles, design trade‐offs, and failure‐mode‐specific advantages. We further emphasize that practical AEMSWE requires integrated multiscale design across catalysts, electrodes, membranes/ionomers, MEAs, cell/stack hardware, and balance‐of‐plant systems. Key unresolved challenges and future perspectives are identified toward selective, durable, scalable, and economically viable AEMSWE for sustainable hydrogen production.