Cobalt nanoparticles supported on nitrogen-doped carbon nanotubes for the efficient oxygen reduction reaction in Mg-air battery

Fabricating the non-precious-metal catalyst with desirable catalytic performance towards oxygen reduction reaction (ORR) is essential for Mg-air battery that adopts neutral brine electrolyte. However, the classic metal-nitrogen-carbon materials with strong ORR catalytic activity in alkaline solution usually display inferior performance than platinum-based catalysts in neutral environment. Herein, we construct a hybrid catalyst composed of cobalt nanoparticles and nitrogen-doped carbon nanotubes, based on pyrolyzing the mixture of melamine, pyrazole, hexadecyl trimethyl ammonium bromide, and 2-methylimidazole chelated with Co2+ and Zn2+ ions. This catalyst possesses abundant ORR catalytic active sites and mesoporous structure with large pore volume, which can result in the superior performance of Mg-air battery than that using Pt/C catalyst. Furthermore, its ORR catalytic mechanism is unraveled according to microstructure characterization and electrochemical response.