A robust bifunctional electrocatalyst for rechargeable zinc-air batteries: NiFe nanoparticles encapsulated in nitrogen-doped carbon nanotubes

摘要

Developing high-efficiency, low-cost, and stable bifunctional oxygen electrocatalysts is essential for the commercialization of rechargeable metal-air batteries. Herein, threedimensional self-assembled microspheres via in situ encapsulation of NiFe alloy nano particles (NPs) into N-doping carbon nanotubes (NiFe@NCNTs) have been achieved through pyrolyzing a mixture of nickel-iron alkoxide and melamine. The as-prepared electrocatalyst exhibits outstanding oxygen reduction reaction (ORR) performance with a half wave potential of 0.79 V and oxygen evolution reaction (OER) activity with a low over potential of 330 mV at 10 mA cm(-2). The eminent activity of NiFe@NCNTs is ascribed to high dispersion of active sites (zero-dimensional core-shell structure of NiFe@NC) and onedimensional conductive network (NCNTs). Accordingly, the zinc-air battery assembled with NiFe@NCNTs as the air cathode exhibits a long cycling life of 200 h with a high energy efficiency of 65.6%. This work may shed new light on the design of advanced bifunctional electrocatalysts toward metal-air batteries. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.