Dynamic Vacancy Self-stabilization Strategy on Sulfur-Doped Mn3O4 for Efficient and Durable Seawater Electrolysis

Abstract Vacancy engineering can enhance Mn-based electrocatalysts, yet in seawater, vacancies often promote Cl– adsorption, metal leaching, and stability loss. Here, we report a dynamic vacancy self-stabilization strategy for sulfur-modified Mn3O4 (S-Mn3O4-E), in which lattice-sulfur oxidation and leaching generate sulfur vacancies together with a sulfate-rich interface, while maintaining high oxygen evolution reaction (OER) activity. Theoretical calculations show that surface sulfate increases the Cl– adsorption energy and induces interfacial electron accumulation, thereby suppressing chloride adsorption, whereas sulfur vacancies regulate the electronic structure and optimize the adsorption energetics of OER intermediates. The optimized S-Mn3O4-E catalyst requires an overpotential of only 221 mV at 10 mA cm–2 in alkaline simulated seawater and sustains continuous operation for 1000 h with a low voltage decay rate of 0.033 mV h–1. This work establishes a rational defect-stabilization approach for the design of active and durable seawater OER catalysts.