Enhancement of oxygen evolution activity of perovskite (La0.8Sr0.2)0.95MnO3-δ electrode by Co phase surface modification

Abstract

Rechargeable metal-air battery and regenerative fuel cells are highly demanded given their high energy density and sustainable nature. Both of them require robust oxygen electrocatalysts improving electrical efficiency. In this work, we use cobalt compounds to modify (La, Sr)MnO3 (LSM) by a hydrothermal method to ameliorate the oxygen evolution reaction (OER) performance. The effects of loading amounts and phase-microstructure of the cobalt phase by adjusting the calcination temperature are systematically investigated. Much improved OER geometrical, specific and mass activities over its individual phase, an onset voltage of 1.38 V and the lowest voltage of 1.68 V at 10 mA cm−2 that are among the best values based on LSM matrix electrocatalysts in the open literature, are obtained. The increased surface oxygen vacancy concentration, water absorption capability, and the modulated surface cations’ electronic structure are ascribed to be the source of the significantly improved electrochemical properties. LSM-Co-RT-12 also showed good durability in constant voltage testing for 10 h. Therefore, integrating with the intrinsically high oxygen reduction activity, the LSM-Co hybrid catalyst possesses promise for bi-functionality oxygen electrocatalysis. This work also highlights the surface modification is an effective method to modify the intrinsic activity of OER inert perovskite materials for the multifunctional application.