Temperature and time dependence study of single-walled carbon nanotube growth by catalytic chemical vapor deposition

The temperature and time dependence of single-walled carbon nanotube (SWCNT) growth by chemical vapor deposition of ethanol on Fe₂O₃/MgO catalyst are compared at both low (∼27 Pa) and atmospheric pressure limits. SWCNTs are synthesized in two reactors with different geometries and operating pressures and are characterized by Raman spectroscopy. Both reactors show SWCNT growth within a relatively narrow temperature window of 700-850 °C, with an optimum growth time of 35 min for the cold wall reactor and 75 min for the quartz tube reactor. A kinetic model comprising of ethanol decomposition, SWCNT formation, and water etching is developed to better understand the growth mechanism. The existence of a temperature window and an optimum growth time in both reactors can be well described by the kinetic model. Simulation results suggest that the temperature and time dependence can be explained by the competition between the growth of SWCNTs and that of amorphous carbon.