Hollow Mesoporous Carbon Nanospheres Decorated with Metal Oxide Nanoparticles as Efficient Earth-Abundant Zinc-Air Battery Catalysts

Hybrids comprising hollow mesoporous nitrogen-doped carbon (HMC) nanospheres and metal-oxide nanoparticles were prepared through a hydrothermal synthesis. These materials exhibit excellent bifunctional catalytic activity in the oxygen reduction and evolution reactions (ORR and OER, respectively) that are core to the efficient operation of Zn-air batteries. When incorporated into prototype devices, Co3O4 and MnCo2O4 nanoparticle-decorated HMC exhibited discharge potentials of 1.26 and 1.28 V at 10 mA cm(-2), respectively. 'CoFeNiO'-decorated HMC exhibited a charging potential of 1.96 V at 10 mA cm(-2). These metrics are far superior to benchmark Pt-Ru, which displayed discharge and charging potentials of 1.25 and 2.01 V, respectively, at the same current density. The battery equipped with Co3O4-decorated HMC demonstrated 63 % initial efficiency before cycling. After cycling at 10 mA cm(-2) for 100 hours, the battery efficiency was maintained at 56.5 %, outperforming the battery with Pt-Ru (50.2 % after 50 h).