Superstructures with Atomic-Level Arranged Perovskite and Oxide Layers for Advanced Oxidation with an Enhanced Non-Free Radical Pathway

Perovskite-based oxides demonstrate a great catalytic efficiency in advanced oxidation processes (AOPs), where both free and non-free radical pathways may occur. The non-free radical pathway is preferable because it is less affected by the wastewater environment, yet little is known about its origin. Here, we exploit Ruddlesden–Popper (RP) layered perovskite oxides as an excellent platform for investigating the structure–property relationship for peroxymonosulfate (PMS) activation in AOPs. The atomic-level interaction of the perovskite and rock salt layers in RP oxides stabilizes the transition metals at low valences, causing the formation of abundant lattice oxygen/interstitial oxygen species. Unlike oxygen vacancies in conventional perovskites, which promote free-radical generation, these reactive oxygen species in RP perovskites have high activity and mobility and facilitate the formation of non-free radical singlet oxygen. This singlet oxygen reaction pathway is optimized by tailoring the oxygen species, leading to the discovery of LaSrCo0.8Fe0.2O4 with exceptionally efficient PMS activation.