Surface Transformation in Lanthanum Nickelate for Enhanced Oxygen Evolution Catalysis

Nickel-based perovskite oxides are identified as promising candidates for oxygen evolution reaction (OER) catalysts in view of their low cost, highly tunable structure, and potential high activity. However, the performance and catalyst design are hindered by their sluggish surface reconstruction kinetics. We introduce a ferric ion pre-etching strategy to enhance the surface reconstruction of typical LaNiO₃. The hydrolysis of ferric ions generates hydrated protons that corrode the La-O terminal sites, inducing lattice distortion and lowering the energy barrier for reconstruction. Concurrently, ferric ion substitution for Ni creates crucial active sites after OER reconstruction, and enables the low-activity LaNiO₃ to become highly active and superior to the benchmark RuO₂ and NiFe layered double hydroxides (LDHs). In situ X-ray absorption spectroscopy (XAS) and in situ Raman spectroscopy reveal substantial surface transformation from corner-sharing to edge-sharing NiO₆ at 1.43 V versus reversible hydrogen electrode (RHE) in the surface pre-etched sample (LNFe^III-spe). This reconstruction is initiated by the lattice oxygen mechanism (LOM) and transitions to the adsorbate evolution mechanism (AEM), underscoring the transformation of distinct OER mechanisms.