Significance of Engineering The MnO 6 Octahedral Units to Promote The Oxygen Reduction Reaction of Perovskite Oxides.

The electronic structure and geometric configuration of catalysts play a crucial role to design novel perovskite-type catalysts for oxygen reduction reaction (ORR). Nowadays, many studies are more concerned with the influence of electronic structure and ignore the geometric effect, which plays a nonnegligible role in enhancing catalytic performances. Herein, we regulate the MnO 6 octahedral tilting degree of LaMnO 3 by modulating the concentration of Y 3+ , excluding the electronic effect from the valence state of manganese. Plotting the MnO 6 octahedral tilting degree as a function of concentration of Y 3+ produces a volcano-shaped plot. The octahedral tilting can reduce the Mn-O covalency, generating more highly active Mn 3+ and oxygen vacancies during ORR process. The specific activity has a positive correlation with octahedral tilting degree. Meanwhile, the octahedral tilting stabilizes Mn-O interactions during ORR process and promote stability. Based on experimental results and DFT calculations, octahedral tilting alters the rate-determining step and decrease the energy barrier. Subsequent extended experiment confirmed that octahedral tilting is the key factor to affect the catalytic performances. This article is protected by copyright. All rights reserved.