Effect of the Amount of Carbon/Nitrogen Feedstocks on Oxygen Reduction Reaction Activity of FeCoNi Nanoparticles Embedded in Nitrogen-doped Carbon Matrix

Carbonaceous transition metal catalysts have become one of the most promising materials to replace expensive Pt-based catalysts because of their high oxygen reduction reaction (ORR) activity and stability. In this paper, three metal-containing nanoparticles, namely FeCoNi, were encapsulated into carbonaceous matrixes by simple stirring and calcination. The morphology of as-obtained FeCoNi particles was controlled and investigated by adjusting the amount of melamine as carbon (and nitrogen) source. FeCoNi@NC/CNTs-6 showed the best ORR activity among all of the catalysts. The half-wave potential of the FeCoNi@NC/CNTs-6 is 0.83 V vs. RHE, and its limiting current density is up to 5.16 mA cm(-2). It was found that the unique 3D carbon-based matrix may be the main reason for this enhanced ORR activity. Additionally, higher content of pyridine N and Fe(Co/Ni)N-x group in FeCoNi@NC/CNTs-6 catalyst may be another reason. Finally, FeCoNi@NC/CNTs-6 was also used as a cathode to assemble the zinc-air battery. The results showed that it had better battery performance than the reference Pt/C catalyst. These results could provide theoretical and practical support for the enlarged applicability of similar catalysts.

Automated summary

Carbonaceous transition metal catalysts have shown promise as alternatives to expensive Pt-based catalysts. This study investigates the ORR activity of FeCoNi nanoparticles encapsulated in carbonaceous matrixes. The results suggest that the unique 3D carbon-based matrix and the presence of pyridine N and Fe(Co/Ni)N-x group in FeCoNi@NC/CNTs-6 catalyst contribute to its enhanced ORR activity.