Restricting Growth of NiFe Nanoparticles on Heteroatom-Doped Carbon Nanotube/Graphene Nanosheets as Air-Electrode Electrocatalyst for Zn-Air Battery.

Exploring bifunctional oxygen electrode catalysts with efficient and stable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) performance is one of the limitations for high-performance zinc-air battery. In this work, NiFe alloy nanoparticles incorporated in three-dimensional (3D) carbon nanotube (CNT)/graphene nanosheet composites with N and S codoping (NiFe/N-S-CNTs) as bifunctional oxygen electrode electrocatalysts for zinc-air battery. The main particle size of NiFe nanoparticles could be well restricted because of the unique 3D structure of carbon nanotube/graphene nanosheet composites (N-S-CNTs). The large specific area of N-S-CNTs is conducive to the uniform dispersion of NiFe nanoparticles. On the basis of the synergistic effect of NiFe nanoparticles with N-S-CNTs, and the sufficient exposure of reactive sites, the synthesized NiFe/N-S-CNTs catalyst exhibits excellent OER performance with a low overpotential of 215 mV at 10 mA cm, and efficient ORR activity with a half-wave potential of 0.877 V. When used as an electrocatalyst in zinc-air battery, the device exhibits a power density of 180.0 mW cm and long term durability for 500 h.