Oxygen Vacancies and Lewis Acid Sites Synergistically Promoted Catalytic Methane Combustion over Perovskite Oxides

An in-depth understanding of the surface properties–activity relationship could provide a fundamental guidance for the design of highly efficient perovskite-based catalysts for the control of anthropogenic methane emission. Herein, both oxygen vacancies and Co n+ Lewis acid sites were purposely introduced on ordered macroporous La0.8Sr0.2CoO3 monolithic catalysts by one-step reduction and selective etching in oxalic acid, and their synergistic effect on methane combustion was investigated. Combined with experimental and theoretical investigations, we revealed that the positively charged Co n+ Lewis acid sites and single-electron-trapped oxygen vacancies (Vo·) formed an active pair, which enabled an effective localized electron cloud shift from Vo· to Co n+. The characteristic electronic effect modulates surface electronic properties and coordination structures, thus resulting in superior oxygen activation capacity, lattice oxygen mobility, and reducibility, as well as favorable CH4 interaction and oxidation. Our work not only gives insights into surface properties–activity relationships on perovskite for hydrocarbon combustion but also sheds substantial light on future environmental catalyst design and modulation for hydrocarbon pollutants elimination.