Influence of Oxygen Vacancies in La0.4Sr0.6FeO3-δ Perovskite Oxide Nanoparticles for the Oxygen Evolution Reaction

Abstract

Oxygen vacancies are important factors to tune the performance of oxide catalysts for the oxygen evolution reaction (OER). However, it remains challenging how to control the concentration of the oxygen vacancies and decouple their effects on OER from other factors. In this work, we use a specific composition/phase La0.4Sr0.6FeO3- d perovskite oxide as an example to tailor the oxygen vacancies of their nanoparticulate using a modified molten salt synthesis and ozone treatment. The OER performance of the resulting La0.4Sr0.6FeO3- d nanoparticles with different degree of oxygen vacancies ranging from 0 to 25% are compared. The OER reactivity increases with increased oxygen vacancies in the materials, but the change is nonlinear. The OER stability, on the other hand, has a bimodal distribution. The activities of fully oxidized sample and the most oxygen-deficient sample degrade slower than the two samples in the middle. The results suggest that it is feasible to design catalysts with oxygen vacancy to be the most OER active and stable. Further investigation into the oxygen vacancy – active site relation would offer guiding principle to design and synthesize high OER performance oxide catalysts.