Promotion of Oxygen Reduction with Both Amorphous and Crystalline MnOx through the Surface Engineering of La0.8Sr0.2MnO3‐δ Perovskite

Abstract Surfaces play a key role in catalysis. Surfaces can be modified in a number of ways, for example by depositing nanoparticles or with functional coating layers. Here, the surface of La 0.8 Sr 0.2 MnO 3‐δ (LSMO) is treated with diluted HNO 3 . This process leads to the preferential formation of MnO x /LSMO on the surface, leading to the exposure of Mn cations at the surface of LSMO. The electrocatalytic activity of the MnO x /LSMO heterostructure towards the oxygen reduction reaction (ORR) is shown to increase when it is compared to the untreated LSMO. Thanks to the formation of MnO x at the surface, the resulting MnO x /LSMO possesses 1) a relatively high specific surface area and a mesoporous structure, 2) a higher coverage of Mn 4+ /Mn 3+ cations at the surface, and 3) a high concentration of highly oxidative oxygen species. This work develops a facile strategy (i. e. HNO 3 treatment) for improving the ORR activity of perovskite oxides in alkaline solution at room temperature.