Boosting the oxygen evolution reaction through migrating active sites from the bulk to surface of perovskite oxides

The oxygen evolution reaction (OER) dominates the efficiency of electrocatalytic water splitting owing to its sluggish kinetics. Perovskite oxides (ABO3) have emerged as promising candidates to accelerate the OER process owing to their high intrinsic activities and tailorable properties. Fe ions in perovskite oxides have been proved to be a highly catalytic element for OER, while some Fe-based perovskites such as SrTi0.8Fe0.2O3-δ (STF) and La0.66Ti0.8Fe0.2O3-δ (LTF) exhibit inferior OER activity. Yet the essential reason is still unclear and the effective method to promote the activity of such perovskite is also lacking. Herein, an in-situ exsolution strategy was proposed to boost the OER by migrating Fe from the bulk to the surface. Significantly enhanced OER activity was achieved on STF and LTF perovskites with surface-decorated oxygen vacancies and Fe nanoparticles. In addition, theoretical calculation confirmed that the oxygen vacancies and Fe nanoparticle on surface could lower the overpotential of OER by facilitating the adsorption of OH−. From this study, migration of the active elements in perovskite is found to be an effective strategy to increase the quantity and activity of active sites, providing new insights and understanding for designing efficient OER catalysts.