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

Abstract 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, 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.