Encapsulation of FeCo–Co Nanoparticles in N-Doped Carbon Nanotubes as Bifunctional Catalysts for Zn-Air Battery

Abstract

The development of low-cost, high catalytic activity oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is the key to promoting the development of zinc-air batteries. In this paper, a simple one-step pyrolysis method was used to successfully synthesize a binary FeCo–Co/NC catalyst with FeCo and Co nanoparticles encapsulated in N-doped carbon nanotubes. This structure exhibits great characteristics: it has a variety of active species (FeCo, Co, NC), and there is close combination between these active species (FeCo, Co, NC). Electrochemical studies have shown that the initial potential of FeCo–Co/NC during ORR process is 0.93 V, the half-wave potential is 0.808 V, and the limiting current density is 4.94 mA cm−2. In the OER process, at an anode current density of 10 mA cm−2, an overpotential of only 353 mV is shown; a lower Tafel slope and good durability are also observed. Moreover, the zinc-air battery in preparation can be cycled for as long as 2000 times. This provides a new method for the preparation of high-efficiency dual-function electrocatalysts for OER and ORR.