Investigation of the behavior of the Ni catalyst in chemical vapor deposition synthesis of carbon nanopearls

Abstract

The role of the nickel catalyst size and its chemical and structural evolution during the early stages of carbon nanopearl nucleation and growth, by chemical vapor deposition from acetylene/argon mixture, was investigated and correlated with the resulting nanopearls morphological and structural properties. Carbon nanopearls were grown using Ni nanoparticles that were 20 nm and 100 nm in size, at a growth temperature of 850 °C, for the following growth times: 10sec, 30 sec, 60 sec, 90 sec, 120 sec and 300 sec. X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy were performed on the carbon nanopearl samples. The X-ray diffraction and X-ray photoelectron spectra showed the following chemical constituents were present during the growth of carbon nanopearls: NiO, Ni₂O₃, Ni₃C, Ni, CO and C (both amorphous and graphite). Transmission electron microscopy showed an increase in carbon nanopearl size with larger Ni nanoparticles. Finally, the results showed that the 20 nm Ni nanoparticles chemically reacted sooner than the 100 nm Ni nanoparticles.