Epitaxially Growth of Heterostructured SrMn3O6-x-SrMnO3 with High Valence Mn3+/4+ for I mproved Oxygen Reduction Catalysis.

Heterostructured catalysts show outstanding performance in electrochemical reactions for 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 oxygen reduction reaction (ORR). The formation of high valence Mn 3+/4+ is beneficial for promoting a positive shift in the d-band center position, 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 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.