Harnessing spinel–metal synergy in MnFe2O4–Co core shell catalysts for sustainable seawater oxidation

Designing electrocatalysts that simultaneously offer high activity and long-term stability in chloride-rich seawater environments remains a formidable challenge in developing practical water-splitting technologies. Herein, we report a novel core@shell MnFe₂O₄–Co CS nanostructure strategically engineered to enhance the oxygen evolution reaction (OER) performance and corrosion resistance of anode materials under seawater electrolysis conditions. The core@shell architecture facilitates strong electronic interactions at the MnFe₂O₄–Co interface, as evidenced by XPS and Raman shifts, which modulate the surface and electronic structure, enhance charge transfer, and lower the energy barrier for OER intermediates. Electrochemical evaluations reveal that MnFe₂O₄–Co CS exhibits a remarkably low onset potential (∼1.48 V vs. RHE), lower Tafel slope, and significantly higher exchange current density, underscoring its superior intrinsic OER kinetics relative to pristine MnFe₂O₄ and Co-based benchmarks. Notably, the Co shell plays a critical role in suppressing metal ion leaching and structural degradation by serving as an effective barrier against chloride-induced corrosion, ensuring exceptional stability over prolonged operation in seawater. These findings elucidate the critical role of core–shell interfacial engineering in modulating reaction kinetics and corrosion resistance, offering a chemically stable and kinetically favorable surface environment for seawater oxidation.