Engineering Dual-Functional La-O Vacancy Associates in a LaMnO_3.15 Perovskite for Enhanced CO and VOC Oxidation

Synergistic activation of lattice oxygen and stabilization of oxygen vacancies are pivotal for optimizing oxygen chemistry and enhancing catalytic performance. However, oxygen vacancies are subjected to being filled and annihilated to form nonreactive lattice oxygen during volatile organic compound (VOC) combustion. Herein, we construct La vacancies to engineer La-O vacancy associates to bridge this dual functionality of stabilizing oxygen vacancies and activating lattice oxygen in the LaMnO_3.15 perovskite. Compared with single vacancies, vacancy associates induce molecular orbital reconstruction and electronic rearrangement within MnO₆ units. This facilitates lattice oxygen activation and oxygen migration to participate in the reaction, stabilizing oxygen vacancies. Thereby, a lower T₉₀ of 163 °C and a stronger stability lasting for 24 h can be achieved in CO combustion. Consequently, such La-O vacancy associates also exhibit enhanced performance in VOC (propane, toluene, and benzene) combustion. By combining a variety of in situ characterizations and density functional theory calculations, the synergy mechanism is revealed, where the lattice oxygen replenishment energy is significantly enhanced, while the oxygen vacancy formation energy adjacent to cation vacancies is markedly reduced. This work provides a fundamental understanding of the relationship between vacancy associates with oxygen chemistry and a promising strategy for catalytic combustion.