Dynamic La Leaching Activates Oxygen-Ligand Holes to Stabilize Mn Oxides for Acidic Oxygen Evolution

Mn oxides are attractive earth-abundant catalysts for the acidic oxygen evolution reaction (OER). However, their durability is constrained by Mn overoxidation under high anodic potential. Here we demonstrate that dynamic La leaching can be harnessed to activate an oxygen-ligand-hole environment in Mn-based oxide (La 0.1 Mn 0.9 O x ), which suppresses Mn overoxidation. Ultraviolet-visible spectra of the electrolyte indicate that incorporating La into γ-MnO 2 shifts the onset potential for Mn VII O 4 − dissolution to a higher value. Operando spectroscopy reveals that La 0.1 Mn 0.9 O x exhibits a much more stable local MnO 6 framework than γ-MnO 2 under OER conditions. Theoretical analysis indicates that, upon Mn-site oxidation, La-leaching-induced metal vacancies amplify oxygen-ligand holes within distorted La─O─Mn motifs, enabling O-to-Mn charge compensation that suppresses Mn overoxidation. The electronic reconfiguration also modulates the Mn d -band center to optimize intermediate adsorption. La 0.1 Mn 0.9 O x delivers an overpotential 66 mV lower than that of γ-MnO 2 at 10 mA cm −2 geo , and sustains stable operation for 5000 h at 10 mA cm −2 geo and 1400 h at 100 mA cm −2 geo . This work highlights leaching-coupled oxygen-electronic regulation as an effective strategy for designing highly stable and active earth-abundant catalysts in acidic OER.