Coupling CoO_x@NC with NiFe LDH Enhances Oxygen Electrocatalysis for Rechargeable High-Efficiency Zn-Air Batteries

Developing bifunctional catalysts with the high oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic activities is of great significance in improving the efficiency of rechargeable Zn-air batteries. Herein, this study adopts simple one-pot pyrolysis and subsequent hydrothermal strategies to prepare a high-performance bifunctional composite catalyst by coupling a layered hydroxide NiFe LDH with Co and N codoped carbon framework, composed of cobalt oxide and metallic Co nanoparticles distributed on interconnected porous carbon nanosheets and carbon nanotubes (CNTs). Benefiting from the exposure of more active sites, high conductivity, and beneficial charge transport advantages, the best catalyst (CoO_x@NC)₂─NiFe demonstrates excellent bifunctional electrocatalytic activities and stability for oxygen-related electrochemical reactions, exhibiting a low potential gap of 0.757 V. Additionally, the rechargeable Zn-air battery assembled with the (CoO_x@NC)₂─NiFe catalyst performs a peak power density of 136 mW cm^-2, and a specific capacity of 803 mAh g_Zn ^-1 at 10 mA cm^-2, and outstanding stability (over 200 hours). This work presents a simple and low-cost approach for synthesizing bifunctional catalysts to realize efficient and durable rechargeable zinc-air batteries.