Reducing the degradation rate and surface segregation of (La_0.5Sr_0.5)FeO_3−δ electrodes in ambient air through multilayering

Transition metal perovskite oxides are employed as air electrode catalysts for solid-oxide fuel cells and electrolyzers. However, degradation linked to cation segregation and precipitation involving alkaline-earth substituents limits their commercialization. In this work, we engineered a multilayer electrode consisting of an ultrathin (La_1−xSr_x)FeO_3−δ catalyst overlayer (x = 0, 0.5), a cation-migration-suppression Pr_0.1Ce_0.9O_2−δ layer, and a bulk-transport (La_0.5Sr_0.5)FeO_3−δ layer. This “trilayer” electrode structure enables the surface reactivity and stability to be optimized independently from the bulk transport: an architecture that mitigates the segregation of available Sr and other cations from the bulk reservoir and their subsequent precipitation at the solid–gas interface. This trilayer architecture reduced surface reaction resistance and long-term degradation by over an order of magnitude at 650 ^∘C over 48 h. The approach offers a general pathway for designing multilayer electrode coatings with decoupled catalytic and transport functionalities.