Epitaxially Grown Heterostructured SrMn3O6−x‐SrMnO3 with High‐Valence Mn3+/4+ for Improved Oxygen Reduction Catalysis

Abstract Heterostructured catalysts show outstanding performance in electrochemical reactions owing to their beneficial interfacial properties. However, the rational design of heterostructured catalysts with the desired interfacial properties and charge‐transfer characteristics is challenging. Herein, we developed a SrMn 3 O 6− x ‐SrMnO 3 (SMO x ‐SMO) heterostructure through epitaxial growth, which demonstrated excellent electrocatalyst performance for the oxygen reduction reaction (ORR). The formation of high‐valence Mn 3+/4+ is beneficial for promoting a positive shift in the position of the d‐band center, thereby optimizing the adsorption and desorption of ORR intermediates on the heterojunction surface and resulting in improved catalytic activity. When SMO x ‐SMO was applied as an air‐electrode catalyst in a rechargeable zinc‐air battery, a high output voltage and power density was achieved, with performance comparable to a battery prepared with Pt/C‐IrO 2 air‐electrode catalysts, albeit with much better cycling stability.