Atomic Engineering of Bifunctional Core–Shell Catalysts with Dual Single‐Atom and Cobalt Nanoparticles for Boosting ORR and OER Kinetics in Zn–Air Batteries

The development of a bifunctional catalyst with superior oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) capabilities is an important key for rechargeable zinc-air batteries (RZABs). In this study, the core-shell synthesis and ammonia treatment strategy are utilized to fabricate novel bifunctional catalysts comprising Fe single atoms, Co single atoms, and Co nanoparticles (Co_NP) in a 3D hierarchical porous nitrogen-carbon framework (NCF), addressed as A-Co-Fe/NCF-Co_NP. The catalyst demonstrates an outstanding ORR and OER activity with a narrow gap of 0.69 V. The ZAB with the novel catalyst and innovatively designed cathode exhibits a maximum power of 294 mW cm^-2 and can be operated for 1129 h (3340 cycles) at 10 mA cm^-2. In the case of the rechargeable flexible zinc-air battery, the ZAB is operated for 210 h (620 cycles) at 2 mA cm^-2. These results show that the ZAB with A-Co-Fe/NCF-Co_NP possesses outstanding stability and durability, which has high potential for ZAB applications.