In Situ Modulation of A-Site Vacancies in LaMnO3.15 Perovskite for Surface Lattice Oxygen Activation and Boosted Redox Reactions.

Modulation of A-site defects is crucial to the redox reactions on ABO3 perovskites for both clean air application and electrochemical energy storage. Herein we report a scalable one-pot strategy for in situ regulation of La vacancies (V La) in LaMnO3.15 by simply introducing urea in the traditional citrate process, and further reveal the fundamental relationship between V La creation and surface lattice oxygen (Olatt ) activation. The underlying mechanism is shortened Mn-O bonds, decreased orbital ordering, promoted MnO6 bending vibration and weakened Jahn-Teller distortion, ultimately realizing enhanced Mn-3d and O-2p orbital hybridization. The LaMnO3.15 with optimized V La exhibits order of magnitude increase in toluene oxidation and ~0.05 V versus RHE (reversible hydrogen electrode) increase of half-wave potential in oxygen reduction reaction (ORR). The reported simple but effective strategy for in situ modulation of La-site defects and the corresponding influence on the electronic structure of MnO6 can benefit the development of novel defect-meditated perovskites in both heterocatalysis and electrocatalysis.