A Bifunctional Hybrid Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions: Nano-Co(3)O(4)-Deposited La(0.5)Sr(0.5)MnO(3) via Infiltration.

For rechargeable metal-air batteries, which are a promising energy storage device for renewable and sustainable energy technologies, the development of cost-effective electrocatalysts with effective bifunctional activity for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has been a challenging task. To realize highly effective ORR and OER electrocatalysts, we present a hybrid catalyst, Co(3)O(4)-infiltrated La(0.5)Sr(0.5)MnO(3-δ) (LSM@Co(3)O(4)), synthesized using an electrospray and infiltration technique. This study expands the scope of the infiltration technique by depositing ~18 nm nanoparticles on unprecedented ~70 nm nano-scaffolds. The hybrid LSM@Co(3)O(4) catalyst exhibits high catalytic activities for both ORR and OER (~7 times, ~1.5 times, and ~1.6 times higher than LSM, Co(3)O(4), and IrO(2), respectively) in terms of onset potential and limiting current density. Moreover, with the LSM@Co(3)O(4), the number of electrons transferred reaches four, indicating that the catalyst is effective in the reduction reaction of O(2) via a direct four-electron pathway. The study demonstrates that hybrid catalysts are a promising approach for oxygen electrocatalysts for renewable and sustainable energy devices.