MOF-derived nitrogen-doped porous carbon (NPC) supported CoFe 2 O 4 nanoparticle composites for high-performance zinc-air batteries

The sluggish kinetics of oxygen reduction reaction (ORR) in air cathode severely hinders the application of rechargeable zinc-air batteries (ZAB). In this work, we construct a composite with CoFe 2 O 4 nanoparticle uniformly implanted into MOF-derived nitrogen-doped porous carbon (CoFe 2 O 4 /NPC) by a dopamine wrapping strategy. The CoFe 2 O 4 /NPC exhibits an outstanding ORR performance in 0.1 M KOH with a half-wave potential (E 1/2 ) of 0.898 V, which is superior to single metal nanoparticle samples (Fe/Fe 2 O 3 /NPC, Co/NPC) and pure CoFe 2 O 4 nanoparticle without NPC. Results suggest that NPC support effect and Fe, Co dual component effect play important roles in boosting the ORR activity of CoFe 2 O 4 /NPC, because the two kinds of effects can regulate the charge transfer of support and CoFe 2 O 4 , and electronic transfer of Fe and Co, and therefore improve the ORR performance. Impressively, using CoFe 2 O 4 /NPC as the cathode catalyst, CoFe 2 O 4 /NPC-based ZAB exhibits a 269 mW cm −2 power density and a long durability over 700 h, which is attributed to the fact that thin carbon layers around the surface of the CoFe 2 O 4 nanoparticles improve the stability. As a result, the CoFe 2 O 4 /NPC catalyst exceeds the upper limit line of the trade-off effect between activity and stability. This work provides a new route for the application of metal-nanoparticle composite in rechargeable zinc-air batteries. Graphical Abstract We synthesized a CoFe 2 O 4 /NPC composite by a dopamine wrapping strategy, and the performance of CoFe 2 O 4 /NPC catalyst exceeds the upper limit line of the trade-off effect between activity and stability of Fe, Co-based catalysts for ZAB applications.