MOF-derived nitrogen-doped porous carbon (NPC) supported CoFe2O4 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 CoFe2O4 nanoparticle uniformly implanted into MOF-derived nitrogen-doped porous carbon (CoFe2O4/NPC) by a dopamine wrapping strategy. The CoFe2O4/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/Fe2O3/NPC, Co/NPC) and pure CoFe2O4 nanoparticle without NPC. Results suggest that NPC support effect and Fe, Co dual component effect play important roles in boosting the ORR activity of CoFe2O4/NPC, because the two kinds of effects can regulate the charge transfer of support and CoFe2O4, and electronic transfer of Fe and Co, and therefore improve the ORR performance. Impressively, using CoFe2O4/NPC as the cathode catalyst, CoFe2O4/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 CoFe2O4 nanoparticles improve the stability. As a result, the CoFe2O4/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.

Automated summary

In this work, a composite material (CoFe2O4/NPC) consisting of CoFe2O4 nanoparticles uniformly implanted into MOF-derived nitrogen-doped porous carbon (NPC) was successfully constructed by a dopamine wrapping strategy. The CoFe2O4/NPC exhibited superior oxygen reduction reaction (ORR) performance compared to other single metal nanoparticle samples. The excellent ORR activity of CoFe2O4/NPC was attributed to the NPC support effect and the Fe, Co dual component effect, which can regulate charge transfer and electronic transfer, thereby improving the ORR performance. Moreover, using CoFe2O4/NPC as the cathode catalyst, a zinc-air battery (ZAB) showed high power density and long durability, indicating the potential application of the CoFe2O4/NPC catalyst in rechargeable zinc-air batteries.