Modelling the growth of carbon nanotubes produced by chemical vapor deposition

An improved model of C2H2 deposition for the growth of carbon nanotubes (CNT) in a horizontal tube reactor has been developed. This includes detailed gas-phase reactions of acetylene pyrolysis, and surface catalytic reactions for CNT growth. Based on this model, the mechanism of CNT growth has been studied by analyzing the change of the CNT growth rate for different growth conditions such as pressure, temperature, number of catalyst nanoparticles per unit area, and diameters of catalyst nanoparticles. The influence of gas-phase reactions and their products on CNT growth has also been evaluated. It is found that although C2H2 is the main contributor to the growth of CNTs, the contribution from the gas-phase products could not be ignored, especially at high temperature.

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► A more realistic model of C2H2 deposition for CNT growth was established.
► The rate limiting step for CNT growth depends on the density of catalyst particles.
► The CNT growth rate rise dramatically as diameters of catalyst particles decrease.
► The gas-phase products, mainly C4H4, are also a contributor to the CNT growth.