Strain‐Driven Surface Reconstruction During the Alkaline Oxygen Evolution Reaction: a Model Thin‐Film Study

Dynamic surface reconstruction critically governs the performance and durability of oxide-based electrocatalysts for the oxygen evolution reaction (OER), yet controlling this process under operating conditions remains challenging. Here, we demonstrate that lattice strain regulates the extent of surface reconstruction in perovskite oxides by modulating the redox behavior of lattice nickel (Ni). Using epitaxial LaNiO3 (LNO) thin films as a model system, we show that strain-induced changes in Ni-oxygen(O) bond length systematically tune the reducibility of Ni3+, thereby controlling the degree of surface reconstruction. Tensile strain enhances Ni reducibility, promotes Ni (oxy)hydroxide formation, and results in a nearly order-of-magnitude increase in reconstruction compared to compressive strain. Under OER conditions in iron (Fe)-containing alkaline electrolytes, tensile-strained LNO exhibits a 5.7-fold enhancement in activity due to synergistic interactions between Fe species and the reconstructed Ni-based surface. By extending this concept to powder-type catalysts through isovalent doping, we demonstrate that modulation of the Ni-O bond length through Scandium (Sc) doping induces comparable surface reconstruction behavior and catalyst activity, thereby confirming the scalability of this approach. These results identify metal-oxygen bond length as a general design parameter for tuning dynamic surface reconstruction and catalytic activity in perovskite oxide electrocatalysts.