Porous calcium–manganese oxide/carbon nanotube microspheres as efficient oxygen reduction catalysts for rechargeable zinc–air batteries

Abstract

The development of a highly efficient, cost-effective electrocatalyst is essential to sustainable energy storage and conversion processes. In this work, we report on porous composite microspheres of the oxygen-deficient perovskite CaMnO_3−δ and carbon nanotubes (δ = 0.23, CMO/CNT), synthesized via co-precipitation with post-hydrothermal treatment as efficient oxygen reduction reaction catalysts for zinc–air batteries. Benefitting from their unique porous spherical structure and synergistic coupling between oxygen-deficient CaMnO_3−δ and carbon nanotubes, the composite catalyst CMO/CNT catalyzes the oxygen reduction reaction via a 4-electron pathway with an excellent oxygen reduction reaction activity, representing a new class of low-cost, efficient and durable electrocatalysts for fuel cells and metal–air batteries.