Effects of Substrates on the Growth Mode of Carbon Fibers

Excellent properties of carbon nanofibers, such as high electrical conductivity, high specific strength, and low mass density, have attracted lots of research interest. The realization of the controllable synthesis of carbon nanofibers is the final purpose through studying the growth mechanism, which has a close relation to reaction conditions for carbon fiber synthesis.

In this study, we have synthesized vapor grown carbon nanofibers on three types of substrates: graphite, ceramic, and titanium dioxide nanotube array, which were coated with copper salt catalyst precursors. Copper salt and acetylene were used as catalyst precursor and carbon source, respectively. The morphology and structure of the as-obtained product were analyzed using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). Experimental results demonstrate that the morphology of carbon fibers synthesized on graphite substrate is similar to that on the ceramic. However, carbon fibers with small diameters of about 20-40 nm were synthesized on the titanium dioxide nanotube arrays. This means, growth substrate plays important roles in the formation of catalyst particles and thereby affects the growth mode of carbon nanofibers.