Abstract
An in-depth understanding of the growth process of single walled carbon nanotubes is of vital importance to the control of the yield of the material and its carbon structure. Using a nickel/silica (Ni/SiOx) catalyst we have conducted a series of growth experiments with a chemical vapour deposition (CVD) system. We find that there is a temperature threshold in the CVD process, and if the reaction temperature sets above this threshold there will be no growth of the nanotubes. In association with this temperature effect, water plays an important role in the promotion or termination of the growth of single walled carbon nanotubes.
Highlights
Catalysts are important for growing carbon-based nanomaterials, such as carbon nanotubes
The nanoparticles were further examined by scanning transmission electron microscopy (STEM) in both bright and dark-field modes (Figures 2B,C) as the dark-field analysis allowed an additional surface information to be obtained from the higher contrast of the nickel relative to the carbon background
The typical feature of carbon nanofibres appeared, i.e., a wider and stronger D peak and a large D/G ratio approaching to 1.0. This indicates that there is a threshold temperature in the chemical vapor deposition (CVD) growth system: if the reaction temperature is above the threshold, there will be no growth of single-walled carbon nanotubes (SWCNTs)
Summary
Catalysts are important for growing carbon-based nanomaterials, such as carbon nanotubes. We report that using a catalytic Ni/SiOx system, which is supported by other catalytic systems, including Fe/ MgO, Fe/K2CO3, Ni/MgO, Fe/NaCl, and Ni/NaCl, as shown in this work, there is a threshold temperature in the CVD growth of single-walled carbon nanotubes.
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