In Situ Growth of NiFe Alloy Nanoparticles Embedded into N-Doped Bamboo-like Carbon Nanotubes as a Bifunctional Electrocatalyst for Zn-Air Batteries.

Developing low-cost catalysts for electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with superior performance in an alkaline solution is of significance for large-scale applications in aqueous zinc-air batteries (ZABs). Herein, we describe the in situ design of embedded NiFe nanoparticles into the N-doped bamboo-like carbon nanotube (NBCNT) with high catalytic performance and stability. The obtained NiFe@NBCNT hybrid exhibits a high electrochemical activity and stability with an unexpectedly low overpotential of ∼195 mV for OER at 10 mA cm-2 and an onset potential at 1.03 V for ORR, superior to the state-of-the-art Pt/C and RuO2 catalysts. Additionally, compared to the mixture of Pt/C and RuO2 cathodes, the ZAB based on the NiFe@NBCNT cathode displays a lower overpotential (0.80 V), higher stable round-trip efficiency (58.3%), and improved power density for 200 cycles at 10 mA cm-2. Apparently, the obtained results indicate that the NiFe@NBCNT hybrid is proven to be one of the best nonnoble metal catalysts for achieving commercial implementation of rechargeable ZABs.