Hierarchically Structured Co(OH)2/CoPt/N-CN Air Cathodes for Rechargeable Zinc-Air Batteries.

For the realization of the large-scale deployment of rechargeable Zn-air batteries, it is crucial to develop cost-effective, efficient, and stable bifunctional electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this work, an integrated electrocatalyst consisting of Co(OH)2/CoPt/N-CN was developed to enable both ORR and OER reactions for Zn-air batteries. The hierarchical Co(OH)2/CoPt/N-CN electrocatalyst has desirable electrochemical properties, with comparable activity and better durability than commercial Pt/C for ORR and improved activity and long-term stability than commercial IrO2 catalyst for OER. When implemented as air-cathode for rechargeable Zn-air batteries, Co(OH)2/CoPt/N-CN exhibited a high power-density of 171 mW cm-2, a specific capacity of 812 mA h g-1, and a robust cycling life. Interestingly, the hierarchical structure remained intact upon charge and discharge tests, suggesting potential long-term use in the Zn-air battery technology. The material development strategy presented here can enrich the toolbox for the design and construction of cost-effective, efficient, and robust bi-functional electrocatalysts for ORR and OER toward rechargeable Zn-air battery applications.