Tunning of optimal parameters for growth of spinnable carbon nanotube arrays at a relatively low temperature and pressure

Spinnable carbon nanotube arrays (spinnable CNTs) combine the multifunctional properties of CNTs and impart unique properties that are absent in disordered CNTs, such as anisotropy, high electrical conductivity, large specific surface area, super hydrophobicity, and high absorbance. Thermal chemical vapor deposition (CVD) is the main method for the preparation of spinnable CNTs. In CVD, the roles of the catalyst, substrate, temperature, gas flow rates, reaction time, and carbon sources have been studied intensively to understand their effect on the process and to identify the precise conditions for high spinnability. However, most studies have been conducted under atmospheric pressure, neglecting the crucial impact of pressure that is often discussed in semiconductor processes. To investigate the effect of pressure, we fabricated spinnable CNTs by thermal CVD in the pressure range of 1-30 kPa. Results showed that the reaction pressure not only influenced the spinnability of the CNT arrays, but also effectively reduced the optimal temperature to 540 degrees C, which was approximately 100 degrees C lower than that in the atmospheric process. In addition, the process executed at lower temperature and low pressure can suppress the leakage of flammable explosive gases, and it is more energy-saving and environmentally friendly.