Nonstoichiometric perovskite for enhanced catalytic oxidation through excess A-site cation

Perovskite oxide has been emerging as one of the efficient heterogeneous catalysts for advanced oxidation of organic contaminants in wastewater because of their structural integrity and compositional tunability. Herein, we report a new perovskite oxide, La_1.15MnO_3+δ with excess La, for a lowered average oxidation state of Mn cations and abundant oxygen vacancies, which can be active sites for peroxymonosulfate (PMS) activation. The La_1.15MnO_3+δ did exhibit improving catalytic performance as compared to LaMnO_3+δ for the degradation of Rhodamine B by activating PMS. Besides, it also demonstrated high tolerance to variant water environments such as temperature, pH and impurity anions. A major non-radical activation mechanism dominated by ¹O₂ was further confirmed in La_1.15MnO_3+δ/PMS system, accompanied by a minor radical pathway. This work provides a new effective strategy to advance catalytic PMS oxidation processes by tailoring the oxidation state of B-site metals and defects of perovskite oxide through manipulating A-site cation stoichiometry.