Iron Base Carbon Nanofibers With Outstanding Performance For Oxygen Reduction Reaction

The oxygen reduction reaction(ORR)is critical for electrochemical energy storage and conversion: in fuel cells and metal-air batteries.A major challenge is to develop cost-effective and durable ORR catalysts,to replace the relatively expensive platinum-carbon(Pt/C)counterparts,particularly for large-scale applications.Despite progress over the past few decades in developing efficient non-precious-metal(NPM)catalysts,such as Fe/FeC3-based materials(the best-known alternatives),most of the reported have yet to sovle sintering problem during thermal treatment.In this paper we fabricated iron nanoparticles embedded in N-doped carbon nanofibers(Fe-N-CNFs)via a simple electrospinning method.At the same time,we studied the influence of Fe for the catalytic performance of oxygen reduction.We also present a porous carbon-base nanofibers with non-sintered iron particals(GP-Fe-N-CNFs).This synthesis method is versatile,which is allowing the well-dispersed iron particles in the range of 5.2-12.2 nm on a high-surface-area support with mesoporous structure.Briefly,Silica colloid(12 nm SiO2 nanoparticles)were employed as templates to realize the mesoporous structures and graphene flakes act as a physical barrier which not only prevents the sintering of iron particles but also keep the particles inside of the fiber rather than expose upon the surface of fiber.And then,graphene acting as a kind of excellent conductive material,enhances the electrical conductivity of the catalyst.The results mentioned above desired features for ORR,which includes a well-dispersed nanoparticles for highly effective intrinsic active sites as well as a mesoporous structure with a high specific surface area.Consequently,the electrocatalyst shows excellent activities and high stabilities in both acid and alkaline media.