Long-term Durability of Seawater Electrolysis for Hydrogen: From Catalysts to Systems.

Direct electrochemical seawater splitting is a renewable, scalable, and potentially economic approach for green hydrogen production in environments where ultra-pure water is not readily available. However, issues related to low durability caused by complex ions in seawater pose great challenges for its industrialization. In this review, a mechanistic analysis of durability issues of electrolytic seawater splitting is discussed. We critically analyze the development of seawater electrolysis and identify the durability challenges at both the anode and cathode. Particular emphasis is given to elucidating rational strategies for designing electrocatalysts/electrodes/interfaces with long lifetimes in realistic seawater including inducing passivating anion layers, preferential OHadsorption, employing anti-corrosion materials, fabricating protective layers, immobilizing Cl on the surface of electrocatalysts, tailoring Cl adsorption sites, inhibition of OH binding to Mg and Ca, inhibition of Mg and Ca hydroxide precipitation adherence, and co-electrosynthesis of nano-sized Mg hydroxides. Synthesis methods of electrocatalysts/electrodes and innovations in electrolyzer are also discussed. Furthermore, the prospects for developing seawater splitting technologies for clean hydrogen generation are summarized. We found that researchers have rethought the role of Cl ions, as well as more attention to cathodic reaction and electrolyzers, which is conducive to accelerate the commercialization of seawater electrolysis.