Elucidating the role of interface of Cu-Co hybrid metal oxide for oxygen reduction reaction in Zn-air batteries

Abstract

Energy security and sustainable energy are becoming more crucial in the current situation. As a result, fuel cells and metal-air batteries have recently received a lot of interest. However, these devices' main drawbacks are the slowness of the oxygen reduction reaction (ORR) and the expense of the catalyst. The necessity for high-performance noble-metal-free electrocatalysts is therefore urgent. This paper describes a CuOx-Co3O4-based heterostructure with nitrogen-doped carbon support (Cu/CuOx-Co3O4/NC-700) as an effective, durable, inexpensive ORR catalyst. The catalyst exhibits good ORR activity with a half-wave potential of 0.81 V vs. RHE with a 6.5 mA cm−2 limiting current density. The observed ORR performances are comparable with benchmark Pt/C catalysts. The Zn-air battery (ZAB), utilizing the synthesized Cu/CuOx-Co3O4/NC-700 catalyst, produces a high open circuit voltage (OCV) of 1.41 V. The catalyst also exhibits a superior specific capacity of 820 mAh gZn−1 and a higher peak power density of 103 mW cm−2. Cu/CuOx-Co3O4 and NC have a strong synergistic impact and are responsible for the enhanced ORR activity. Hence, Cu/CuOx-Co3O4 heterostructures introduced oxygen vacancies, high surface area, desirable charge transfer, and unsaturated chemical bonds in the interface to create a charge redistribution. As a result, the catalytic activity has improved significantly.