Top-down synthesis of three-dimension ABO₃-type perovskite oxides with rich grain boundaries and lattice defects for molecular oxygen activation in catalytic oxidation reactions

Perovskite oxides are potential materials that can replace noble metals for industrial catalysis. However, the high temperature (> 700 °C) necessitated in the preparation process causes the lack of low-coordinated defect sites that are essential for catalytic reactions. To this end, herein we develop a top-down strategy to synthesize ABO₃-type perovskite, by selectively etching the non-perovskite unit of a Ruddlesden-Popper (R-P) compound. The etching treatment not only promotes the formation of stable, three-dimensions reticular structure composed of nanosheets, but also generates rich amounts of grain boundaries and lattice defects, altering the electronic and surface properties. The LaMnO₃, obtained by etching the La-O unit of R-P La₃Mn₂O₇, exhibits not only enriched grain boundaries and lattice defects, but also excellent surface hydrophobicity. Moreover, the material possesses surface area up to 212.3 m²/g, which is the highest value for perovskite oxides reported in literature, to the best of our knowledge. Owing to these exciting properties, the LaMnO₃ shows prominent catalytic performances for oxygen involved oxidation reactions, including the full oxidation of volatile organic compounds and partial oxidation of alcohols, with stable activity and strong resistance to water. These results potentiates that the top-down strategy is a promising method to synthesize ABO₃-type perovskites and could be a power to promote their progress for industrial catalysis.