High stability cubic perovskite Sr0.9Y0.1Co1-xFexO3-δ oxygen evolution by phase control and electrochemical reconstruction

Abstract

Transition metal oxides are considered ideal electrocatalyst materials due to their low cost and high intrinsic activity. Among them, SrCoO_3-δ has received increasing attention due to its multi-phase structure and tunable electronic properties, though its OER reaction kinetics and catalysis stability are unsatisfactory. Herein, based on a simple one-step solid-state reaction method, we use a small amount of rare earth Y ions (10%) to transform H-SCO_2.52 from a hexagonal structure to a stable cubic perovskite Sr_0.9Y_0.1CoO_3−δ. While broadening the atomic ratio of Co and Fe in the B-site under the cubic perovskite Sr_0.9Y_0.1Co_1-xFe_xO_3−δ (x = 0~1), the relationship between the B-site electronic state, oxygen vacancies, and OER performance has been explored. Sr_0.9Y_0.1Co_0.2Fe_0.8O_3−δ with a high concentration of oxygen vacancies, exhibits the lowest overpotential of 277 mV and maintains stability at 10 mA cm^-2 for 88 hours. The valence states of Fe and Co atoms in SYC0.2F0.8 O are optimized (Fe²⁺~50.81%, Co²⁺~19.39%), and the oxygen evolution activity is enhanced by electrochemical reconfiguration to form high-valence Fe and Co ions. Selective leaching of Sr ions via electrochemical surface reconstruction activates FeOOH and CoOOH amorphous layer active sites on the catalyst surface, significantly enhancing reaction kinetics.