Seawater electrolysis for green hydrogen: A critical review of challenges, advances, and future directions

Seawater electrolysis (SWE) is an emerging pathway for green hydrogen production, offering a sustainable solution that leverages abundant saline water and renewable energy integration. This review presents a comprehensive overview of the key challenges, technological advances, and future directions of SWE, covering developments from material-level innovations to system-scale designs. Major technical barriers such as chloride-induced corrosion, pH variability, and competition between oxygen evolution (OER) and chlorine evolution reactions (CER) are critically examined. The review highlights recent progress in electrocatalyst engineering, particularly nanostructured catalysts like NiFe-based layered double hydroxides (LDHs), which have demonstrated superior selectivity, corrosion resistance, and operational stability. Additional strategies, including surface modification, permselective barriers, and Lewis acid incorporation, are discussed as effective methods to mitigate degradation caused by halide ions and insoluble precipitates. System-level solutions such as desalination-integrated SWE units and renewable energy coupling have shown significant potential to reduce overpotentials and capital expenditures, with some case studies reporting up to 46 % cost savings. Innovative approaches, including membrane-less configurations, triboelectric-assisted systems, and microfluidic electrolyzers, have enhanced lab-scale performance and point toward scalable designs. The review also addresses the techno-economic viability of SWE, especially in coastal regions with limited freshwater availability. Finally, future opportunities in SWE research lie in the development of next-generation catalysts, hybrid desalination-electrolysis systems, and supportive energy policy frameworks that will enable widespread adoption of SWE as a cornerstone of the global green hydrogen economy. • SWE enables sustainable H 2 production using abundant seawater and renewable integration. • Chloride corrosion and CER competition remain key barriers to large-scale SWE deployment. • NiFe-LDH catalysts show high OER selectivity, stability, and corrosion resistance. • Desalination-hybrid SWE cuts costs by up to 46 % and improves system performance. • Lab-scale membraneless and microfluidic designs advance scalable SWE technologies.