Morphology optimization of CCVD-synthesized multiwall carbon nanotubes, using statistical design of experimen

Abstract

The possibility of optimization of morphological features of multiwall carbon nanotubes (MWCNTs) using the statistical design of experiments (DoE) is investigated. In this study, MWCNTs were synthesized using a catalytic chemical vapour deposition (CCVD) method in a horizontal reactor using acetylene as the carbon source. The effects of six synthesis parameters (synthesis time, synthesis temperature, catalyst mass, reduction time, acetylene flow rate and hydrogen flow rate) on the average diameter and mean rectilinear length (MRL) of carbon nanotubes were examined using fractional-factorial design (FFD) coupled with response surface methodology (RSM). Using a 2_III^6–3 FFD, the main effects of reaction temperature, hydrogen flow rate and chemical reduction time were concluded to be the key factors influencing the diameter and MRL of MWCNTs; then Box–Behnken design (BBD) was exploited to create a response surface from the main factors. The total number of required runs is 26: 8 runs are for FFD parameter screening, 17 runs are for the response surface obtained by the BBD, and the final run is used to confirm the predicted results.