Formation mechanism of carbon-encapsulated iron nanorods in a co-carbonization process

[Display omitted] ► Carbon-encapsulated iron nanostructures were prepared by a co-carbonization process. ► Carbon-encapsulated iron nanorod evolves from carbon-encapsulated iron nanoparticle. ► Cooling process is essential to the formation of carbon-encapsulated iron nanorod. Carbon-encapsulated iron nanostructures were prepared by co-carbonization of a mixture of aromatic heavy oil and ferrocene. The morphologies and structural features of the iron/carbon composites were investigated using transmission electron microscopy, high-resolusion transmission electron microscopy and X-ray diffraction measurements. It was found that, by increasing the reaction temperature from 420 to 450 °C the product was changed from nanoparticle to nanorod. The morphologies of the products prepared at 440 °C proved the relationship between nanoparticle and nanorod. Therefore, a model was established to explain the formation mechanism of carbon-encapsulated iron nanorods from the aggregation and self-assembly of partially fused carbon-encapsulated iron nanoparticles.