Vacancy-Activated Surface Reconstruction of Perovskite Nanofibers for Efficient Lattice Oxygen Evolution

Inducing the surface reconstruction of perovskites to promote the oxygen evolution reaction (OER) has garnered increasing attention due to the enhanced catalytic activities caused by the self-reconstructed electroactive species. However, the high reconstruction potential, limited electrolyte penetration, and accessibility to the perovskite surface greatly hindered the formation of self-reconstructed electroactive species. Herein, trace Ce-doped La_0.95Ce_0.05Ni_0.8Fe_0.2O_3-δ nanofibers (LCNF-NFs) were synthesized via electrospinning and postcalcination to boost surface reconstruction. The upshift of the O 2p band center induced by the rich oxygen vacancies lowered the reconstruction potential, and the specific one-dimensional nanostructure effectively enabled enhanced electrolyte accessibility and permeation to the LCNF-NFs. These collectively caused massive in situ generation of self-reconstructed electroactive Ni/FeO(OH) species on the surface. As a result, the surface-reconstructed LCNF-NFs exhibited accelerated lattice kinetics with a comparatively lower Tafel slope of 50.12 mV dec^-1, together with an overpotential of only 342.3 mV to afford a current density of 10 mA cm^-2 in 0.1 M KOH, which is superior to that of pristine LaNi_0.8Fe_0.2O_3-δ nanoparticles (NPs) and the same stoichiometric La_0.95Ce_0.05Ni_0.8Fe_0.2O_3-δ NPs, commercial IrO₂, and most of the state-of-the-art OER electrocatalysts. This study provided deep insights into the surface reconstruction behaviors induced by oxygen defects and an intellectual approach for constructing electroactive species in situ on perovskites for various energy storage and conversion devices.