In situ modulation of a-site vacancies in LaMnO${}_{3.15}$ perovskite for surface lattice oxygen activation and boosted redox reactions

Modulation of A-site defects is crucial to the redox reactions on ABO${}_3$ 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 LaMnO${}_{3.15}$ by simply introducing urea in the traditional citrate process, and further reveal the fundamental relationship between V${}_{La}$ creation and surface lattice oxygen (O${}_{latt}$) activation. The underlying mechanism is shortened Mn-O bonds, decreased orbital ordering, promoted MnO${}_6$ bending vibration and weakened Jahn-Teller distortion, ultimately realizing enhanced Mn-3d and O-2p orbital hybridization. The LaMnO${}_{3.15}$ with optimized V${}_{La}$ exhibits order of magnitude increase in toluene oxidation and ca. 0.05 V versus RHE (reversible hydrogen electrode) increase of half-wave potential in oxygen reduction reaction (ORR). The reported strategy can benefit the development of novel defect-meditated perovskites in both heterocatalysis and electrocatalysis. (© 2021 Wiley‐VCH GmbH)