Oxygen Vacancy-Mediated RuO2– x /Mn3O4– x Heterojunction with Ru–O–Mn bridge bonds for Stable and Chloride-Resistant Seawater Electrolysis

Abstract Developing electrocatalysts that simultaneously deliver high activity and robust chloride resistance remains a critical challenge for direct seawater electrolysis. In this work, we present an oxygen vacancy-mediated RuO2–x/Mn3O4–x heterojunction catalyst fabricated via a facile salt-sealing strategy followed by thermal treatment. The heterointerface engineering generates Ru–O–Mn bridge bonds that promote efficient electron transfer from Mn to Ru, effectively lowering the Ru valence state and circumventing its over-oxidation during prolonged electrolysis. Meanwhile, the Mn component in the heterojunction exhibits an electron-deficient surface state that strengthens OH– adsorption, creating a competitive binding environment that repels Cl– and confers exceptional chloride corrosion resistance. As a result, the optimized RuO2–x/Mn3O4–x catalyst demonstrates remarkable durability over 50 h of continuous seawater electrolysis at 10 mA cm–2, requiring ultralow overpotentials of only 250 and 440 mV to reach current densities of 10 and 100 mA cm–2, respectively, in 1 M KOH with 0.5 M NaCl.