Ferromagnetic-antiferromagnetic interfaces in MAX phase electrocatalysts: a spin-driven platform for enhanced oxygen evolution reaction

The oxygen evolution reaction (OER) is limited by high activation barriers and sluggish kinetics, constraining the efficiency of water electrolysis. Spin-polarized electrons on catalyst surfaces are crucial for generating parallel spin-aligned oxygen, thereby enhancing OER performance. This study introduces a novel electrocatalyst system using a ferromagnetic (FM) MAX phase to improve spin-enhanced OER activity. Through isomorphous replacement, we synthesized the Ti₂FeN (TFN) MAX phase with excess iron toppling onto its surface (T-TFN). Unlike the pristine TFN with a Curie temperature (T_C) of 208 K, T-TFN exhibits room-temperature ferromagnetism, with a T_C exceeding 300 K. When paired with non-FM Co₃O₄ nanoparticles, the T-TFN/Co₃O₄ hybrid system demonstrates significantly enhanced OER activity under an external magnetic field. The FM ordering in T-TFN induces spin alignment at the TFN/Co₃O₄ interface via the spin-pinning effect, reducing electron-electron repulsion and facilitating efficient charge transfer. This synergy of high conductivity and room-temperature ferromagnetism in T-TFN creates an effective platform for magnetic field-assisted electrocatalysis. The hybrid system highlights the potential of FM MAX phases as a catalyst support, paving the way for more efficient OER and advancements in water-splitting technologies.