Optimizing chemical vapor deposition parameters to attain minimum diameter carbon nano tubes by response surface methodology

The MWCNTs (Multi walled carbon nano tubes) with diameter closer to SWCNTs (Single walled carbon nano tubes) found to have superior mechanical strength compared to the larger diameter of MWCNTs. Thermal chemical vapor deposition (CVD) process is widely used to synthesize multiwall carbon nano tubes. The main issue faced in the synthesis of carbon nano tubes (CNTs) via CVD process is the selection of optimum parameters for the growth of well aligned and required diameter of CNTs. This issue may be rectified by the correlating parameters of CVD process (reaction temperature, flow rate of precursor gas and process time) and the output product morphology of MWCNTs. The main aim of this research work is to optimize CVD process parameters to attain minimum diameter multi wall CNTs. For this purpose, statistical tools such as design of experiments, analysis of variance and response surface methodology were utilized. The FESEM (Field emission scanning electron microscopy) and HRTEM (High resolution transmission electron microscopy) techniques were used to study the characteristics of MWCNTs. The optimum CVD parameters were found at 1000°C reaction temperature, 120 ml/min flow rate of precursor gas and 35 mins process time. This combination of parameters yielded a minimum diameter multiwall CNTs of 17 nm.