Facile synthesis of CO/N-doped carbon nanotubes and the application in alkaline and neutral metal-air batteries

Nonprecious transition metals [e.g., cobalt (Co), iron (Fe), and zinc (Zn)], and nitrogen doped carbon materials are considered to be the most attractive alternatives to precious metal catalysts. Herein, Cobalt decorated nitrogen-doped carbon nanotubes were synthesized via a facile hydrothermal method and calcination. Benefiting from the N-doping, etching of Co nanoparticles to carbon nanotubes and synergistic effect between the components, the as prepared Co/nitrogen-doped carbon nanotubes (Co-NCNT) displays a half-wave potential of 0.88 V (vs. RHE), a limiting current density of 5.6 mA cm -2, and electron transfer number of 3.9 in 0.1 M KOH. When applied in metal-air batteries, it delivered maximum power densities of 130.0 mW cm -2, 117.3 mW cm -2 and 58.6 mW cm -2 in alkaline Zn-air, Al-air batteries and neutral Mg-air batteries respectively, outperforming the commercial Pt/C. These demonstrate that the synthesized Co-NCNT is a promising candidate for ORR in metal-air batteries with both alkaline and neutral electrolytes. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Nonprecious transition metals and nitrogen doped carbon materials are considered as attractive alternatives to precious metal catalysts. Cobalt decorated nitrogen-doped carbon nanotubes show promising performance in metal-air batteries, outperforming commercial Pt/C. This demonstrates the potential of Co-NCNT as a candidate for ORR in metal-air batteries.