A comprehensive investigation of Sr segregation effects on the high-temperature oxygen evolution reaction rate

Abstract

While the effects of Sr segregation on the performance and stability of perovskite electrodes in solid oxide electrolysis cells (SOECs) have been widely studied, most attention has been focused on surface Sr segregates, with the impact of the resulting Sr deficiencies within the bulk phase of the electrodes largely ignored. Here, we report our findings from an investigation into the impact of Sr deficiencies in the SrCo_0.7Fe_0.3O_3−δ (SCF) lattice and surface Sr segregates on the electrochemical behavior of well-controlled anode materials. Results demonstrate that Sr deficiencies in the perovskite lattice significantly enhance bulk oxygen ion transport, while surface Sr segregates suppress oxygen vacancy formation at interfaces, resulting in a reduced rate of oxygen exchange and lower surface electrical conductivity. Our study provides critical insights into the roles of bulk Sr deficiencies and surface Sr segregates, particularly their effects on oxygen vacancy formation, electrical conductivity, oxygen ion transport, and the overall rate of a high-temperature oxygen evolution reaction.