Triggering Spontaneous Reconstruction of Ruddlesden-Popper Perovskites for Enhanced Oxygen Evolution

Understanding catalyst reconstruction is crucial for the rational design of oxygen evolution reaction (OER) electrocatalysts, yet spontaneous chemical reconstruction in alkaline environments remains insufficiently understood. Herein, we demonstrate that alkali-triggered chemical reconstruction, rather than electrochemical activation, can effectively generate highly active surface species. Using the Ruddlesden-Popper perovskite La_0.5Sr_1.5Ni_0.75Fe_0.25O_4 ± δ (LSNF) as a model catalyst, an approximately 17-fold enhancement in OER current density at 1.55 V versus RHE is achieved after KOH immersion, accompanied by a reduced overpotential of 287 mV at 10 mA cm^-2 (86 mV lower than pristine LSNF). Spectroscopic and microscopic analyses reveal that KOH immersion triggers elemental leaching and Ni reconfiguration, forming an amorphous Ni hydr(oxy)oxide surface layer enriched with Fe. This strategy is also applied to other perovskites (La_1-xSr_xNi_0.75Fe_0.25O_3-δ, x = 0.2, 0.5), demonstrating its general applicability. This work highlights the role of concentrated alkali in driving chemical reconstruction and linking dynamic structural evolution with catalytic performance.