Controllable synthesis and purification of carbon nanofibers and nanocoils over water-soluble NaNO3

In order to avoid the complicated purification process of carbon nanomaterials (CNMs) and obtain high-purity CNMs, NaNO3 powder was used as catalyst for the synthesis of CNM. By controlling the decomposition temperature (400 and 450 °C), liner carbon nanofibers and helical carbon nanofibers can be selectively synthesized. Because of the used catalyst is water-soluble, it can be removed easily from the products by water washing and high-purity CNMs can be obtained undamaged. It is worth pointing out that the use of water-soluble salts as catalyst is new and the approach bypasses the scabrous problems related to CNM purification.