Effect of using chlorine-containing precursors in the synthesis of FeNi-filled carbon nanotubes

A method for the in situ filling of thin-walled carbon nanotubes (CNTs) with long continuous ferromagnetic nanowires is described, using chlorine substituted benzene, C6H6−xClx (x = 0–3), as the carbon precursor. This method can be used to prepare not only single-metal (e.g. Fe, Co, Ni) nanowires, but also alloy (e.g. FeNi) nanowire-filled CNTs. As an example, we show the successful synthesis of FeNi-filled CNTs. A ratio din/W is used to evaluate quantitatively the hollow degree of CNTs, where din is the inner diameter and W is the wall thickness of a nanotube. The larger this ratio is, the wider inner cavity of the CNTs will be. Statistical results show that the hollow degrees of CNTs increase with the increase of Cl content in carbon precursors, which in turn affords a convenient way to control the hollow degrees of CNTs.