Enhanced oxygen evolution of metastable LaFeCoNiMnMo high-entropy alloys produced by La-induced intense lattice distortion

High-entropy alloys (HEAs) are characterized by localized atomic-scale lattice distortions that can regulate the adsorption of intermediates during electrocatalysis. However, conventional 3 d HEAs exhibit limited atomic size mismatch, leading to insufficient lattice distortion and weak strain effects, which restrict adsorption tuning and spin-dependent electronic regulation for the oxygen evolution reaction (OER). Herein, a large-radius rare-earth element, lanthanum (La), was incorporated into a multicomponent HEA via a transient high-temperature shock strategy, suppressing phase separation and enabling a metastable single-phase LaFeCoNiMnMo HEA. Structural analysis confirms that La incorporation enhances lattice distortion and induces pronounced strain effects. The catalyst exhibits excellent OER performance, delivering an overpotential of 190 mV at 10 mA cm −2 and stable operation for 95 h. Magnetic measurements reveal that strain drives spin-state evolution, increasing the effective magnetic moment and spin polarization. Density functional theory (DFT) calculations demonstrate that strain induced by lattice distortion breaks the local crystal-field symmetry and modulates d -orbital splitting, leading to optimized adsorption energetics of oxygenated intermediates. This strain-spin-electronic structure coupling lowers the reaction energy barrier and accelerates OER kinetics. This work establishes a strain-driven spin-state regulation mechanism and provides a strategy for designing advanced electrocatalysts via rare-earth-induced electronic and spin modulation.