Surface-oxidized Fe–Co–Ni alloys anchored to N-doped carbon nanotubes as efficient catalysts for oxygen reduction reaction

Abstract

Developing a cheap, efficient, and stable oxygen reduction reaction (ORR) catalyst for fuel cells has the potential to help address the energy crisis. This work reports low-cost ternary transition metal alloy nanoparticles anchored to nitrogen-doped carbon nanotubes (N-CNTs), i.e., Fe2Co2Ni2/N-CNTs, as an efficient ORR catalyst. The ORR performance of this ternary metal-based catalyst was found to be better than that of binary metal-based catalysts. The non-uniformities in the metal oxide layer, formed on the surface of the alloy particles, provided more ORR active sites. This novel core-shell structure of the alloy particles allowed Fe2Co2Ni2/N-CNTs to catalyze ORR efficiently. This catalyst exhibits an onset potential of 0.811 V vs RHE, a half-wave potential of 0.749 V vs RHE, and a limiting current density of 5.28 mA cm−2 for ORR, which is close to commercial Pt/C and most previously reported catalysts. Notably, Fe2Co2Ni2/N-CNTs exhibits better stability and resistance to methanol than Pt/C catalysts. These results indicate that the catalysts based on ternary transition metal alloy nanoparticles anchored to carbon materials have great potential for storage and transformation of clean energy.