Atomic Insights into Nanoparticle Exsolution from Planar Defect-Engineered Perovskite Oxide Catalysts

Inspired by surface functionalization in perovskite exsolution catalysts, planar defects outperform low-dimensional defects in shaping nanoparticle (NP) exsolution behavior. However, their specific impact remains elusive owing to controlled synthesis challenges and entangled coexisting material features. We fabricated Ruddlesden-Popper (RP) fault-engineered LaNi0.5Fe0.5O3 film through a dual modulation strategy, and combined advanced electron microscopy, spectroscopy and electrochemical tests for systematic investigation. Moderate RP faults induce lattice perturbation and charge redistribution, creating facile and directional diffusion pathways to optimize surface metallic NP exsolution. The upshifted d-band center of the improved surface area yields 101.2 mA cm-2 oxygen evolution reaction (OER) current density at 1.6 V (∼950% higher than the defect-free counterpart) and a 67 mV dec-1 Tafel slope. However, excessive RP faults disrupt the long-range lattice order, hindering surface NP exsolution and lowering OER activity. This work reveals the RP fault-NP exsolution coupling mechanism, guiding rational design of high-performance exsolution electrocatalysts.