Seawater electrolysis for hydrogen production: Challenges, innovations, and future pathways

The growing global demand for green hydrogen has intensified interest in seawater electrolysis (SWE) as a sustainable pathway, particularly for regions with limited access to freshwater. However, SWE poses unique scientific and engineering challenges that differ from those in purified water electrolysis, including chloride-induced corrosion, parasitic chlorine evolution reactions (ClER), membrane degradation, and catalyst instability in complex ionic matrices. This review provides a critical assessment of recent advances and persistent challenges in SWE, with emphasis on material innovations, membrane selectivity, and cell design strategies. The review begins with an outline of the fundamental electrochemical and thermodynamic principles governing SWE, followed by a detailed discussion on chlorine suppression via advanced electrocatalysts and selective membrane technologies, such as anion exchange membranes (AEMs) and emerging bipolar membranes (BPMs). The role of interface engineering, heterostructure formation, and photothermal enhancement in improving catalytic activity and durability is critically examined. Novel electrolyzer configurations, including sulfur-assisted electrolysis, vapor-phase protonic ceramic cells, and boron-doped diamond-supported electrodes were documented based on their potential to enhance energy efficiency and operational lifetime. Additionally, the review integrates techno-economic considerations and sustainability to explain the practical feasibility of SWE systems. By consolidating findings from recent studies, this work identifies key knowledge gaps and outlines future directions for scalable, chlorine-tolerant, and energy-efficient SWE platforms. The merging of materials chemistry, membrane science, and system engineering is essential to transition SWE from laboratory demonstrations to commercially viable hydrogen production.