SrCo_0.9Ti_0.1O_3-δ As a New Electrocatalyst for the Oxygen Evolution Reaction in Alkaline Electrolyte with Stable Performance

The development of efficient, inexpensive, and stable electrocatalysts for the oxygen evolution reaction (OER) is critical for many electrochemical energy conversion technologies. The prohibitive price and insufficient stability of the state-of-the-art IrO₂ electrocatalyst for the OER inhibits its use in practical devices. Here, SrM_0.9Ti_0.1O_3-δ (M = Co, Fe) perovskites with different B-site transition metal elements were investigated as potentially cheaper OER electrocatalysts. They were prepared through a typical sol-gel route, and their catalytic activities for the OER in alkaline medium were comparatively studied using rotating disk electrodes. Both materials show high initial intrinsic activities in alkaline electrolyte for the OER, comparable to the benchmark perovskite-type electrocatalyst Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF), but SrCo_0.9Ti_0.1O_3-δ (SCT) possessed more operational stability than SrFe_0.9Ti_0.1O_3-δ (SFT), even better than BSCF and IrO₂ catalysts. Based on the X-ray photoelectron spectra analysis of the oxidation states of the surface Co/Fe in both SFT and SCT before and after the OER tests, an explanation for their different operational stabilities was proposed by adopting a reported activity descriptor correlated to the e_g occupancy of the 3d electron of the surface transition metal cations in the perovskite oxides. The above results indicate that SCT is a promising alternative electrocatalyst for the OER and can be used in electrochemical devices for water oxidation.