Electronic and surface engineering of Mn active sites by femtosecond lasers: enhancing catalytic performance for seawater electrolysis through Mn4+–OH− layers†

Abstract

Laser-induced modifications of La_0.51Sr_0.49MnO₃ (LSMO) perovskite electrocatalysts are explored for enhanced seawater oxidation under alkaline conditions. Femtosecond (FS) laser treatment stabilizes Mn in the high oxidation state (Mn⁴⁺), significantly altering the electronic structure and surface morphology of the catalyst. These changes lead to increased covalency between the Mn d-band and O 2p orbitals, facilitating efficient charge transfer and lowering activation barriers for oxygen evolution reaction (OER) intermediates. Laser treatment also induces a porous, roughened surface, enhancing active site density, hydrophilicity, and ion exchange, while minimizing Jahn–Teller distortions to further stabilize the catalyst during the OER. Additionally, the formation of a robust hydroxide layer protects against corrosive species in seawater, ensuring long-term durability. These combined effects result in significantly improved OER kinetics, selectivity, and stability, positioning laser-treated LSMO (LT-LSMO) as a promising candidate for direct seawater electrolysis applications.