Significance of Engineering the MnO6 Octahedral Units to Promote the Oxygen Reduction Reaction of Perovskite Oxides

Abstract

AbstractThe 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, this work regulates the MnO6 octahedral tilting degree of LaMnO3 by modulating the concentration of Y3+, excluding the electronic effect from the valence state of manganese. Plotting the MnO6 octahedral tilting degree as a function of concentration of Y3+ produces a volcano‐shaped plot. The octahedral tilting can reduce the Mn−O covalency, generating more highly active Mn3+ 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 (RDS) and decrease the energy barrier. Subsequent extended experiment confirms that octahedral tilting is the key factor to affect the catalytic performances.