CNTs@Fe–N–C core–shell nanostructures as active electrocatalyst for oxygen reduction

Abstract

The development of non-precious metal catalysts for oxygen reduction reactions (ORRs) is of extreme importance for the construction of efficient H₂/O₂ polymer electrolyte membrane fuel cells (PEMFCs), one of the most promising clean energy technologies. Herein, we report the fabrication of core–shell structured CNTs@Fe–N–C composites with a Fe–N–C shell closely wrapped around a core of CNTs (carbon nanotubes) as efficient catalysts for ORR. CNTs@Fe–N–C composites afford comparable activity to commercial Pt/C catalysts with a loading of 20 μg Pt cm⁻² towards ORR in alkaline media. The results of XRD, TEM, XPS and ⁵⁷Fe Mössbauer characterizations suggest that the high ORR activity of CNTs@Fe–N–C composites are mainly attributed to the combined advantages of the unique core–shell nanostructure allowing close contact between Fe–N–C and CNTs, uniformly distributed FeN4/C species, and the presence of pyridine and graphitic nitrogen.