Suppressing cation segregation on lanthanum-based perovskite oxides to enhance the stability of solid oxide fuel cell cathodes

The slow rate of oxygen reduction reaction (ORR) at the cathode side has been considered as a scientific challenge to improve the overall performance of solid oxide fuel cell (SOFC). Unfortunately, dopant cation enrichment on the surface of perovskite-type cathode materials often leads directly to the reduction in activity and stability of ORR. For this reason, we quantitatively assessed the main driving force of dopant segregation on LaBO 3 (001) surfaces (B = Cr 0.50 Mn 0.50 , Mn, Fe, Co 0.25 Fe 0.75 , Co, and Ni) using density functional theory (DFT) calculations. Based on our findings, the minimization of elastic energy, which is closely related to the size of both A-site and B-site cations, plays an important role on the A-site dopant segregation. The degree of dopant segregation can be controlled by the proper choice of cations contained in LaBO 3 -type perovskite oxides. We therefore suggest a valuable principle that can be applied to design high performance cathode materials by suppressing the dopant cation enrichment at the surface. Relieving the elastic interaction, which is a key origin of dopant segregation on the surface of LaBO 3 -type perovskites, by using the proper A- and B-site cations is a way to suppress the dopant segregation which often degrades SOFC performance.