Fabrication of carbon nanomaterials by chemical vapor deposition

This work reports carbon nanomaterials including carbon nanotubes (CNTs) and carbon onions fabricated by chemical vapor deposition of methane over nano-sized Ni/Al catalyst at 450–600 °C. The as-obtained carbon nanomaterials were systematically characterized by transmission electron microscopy and X-ray energy dispersive spectroscopy to investigate effects of the composition of Ni/Al catalyst and the reaction temperature on the morphology of carbon nanomaterials. The results showed that CNTs and carbon onions were synthesized at moderate temperatures. The composition of Ni/Al catalyst and the reaction temperature have great influences on the morphology of carbon nanomaterials. When using a relatively higher reaction temperature (550–600 °C) and a catalyst with relatively low Ni content (<40 wt%), a morphologically pure long CNTs can be produced. When using a catalyst with relatively high Ni content (>60 wt%), a morphologically pure carbon onions can be obtained. These evidences provide insight into the CNT and carbon onion growth mechanisms.