Influence of CO 2 and N 2 on the growth of carbon nanotubes by using thermal chemical vapor deposition

Abstract

Carbon nanotubes (CNTs) have been grown efficiently on a Si substrate by thermal chemical vapor deposition using CH 4 and CO 2 gas mixtures. Fe catalytic nanoparticles were deposited on Si and carbon cloth substrates. This process is apparently different from the conventional process in gas mixtures of H 2/CH 4, H 2/C 2H 2, NH 3/CH 4, H 2/C 6H 6 and others. Carbon dioxide is used to replace the harmful gases of H 2 and NH 3 and the addition of N 2 in the mixture gas of CH 4 and CO 2 obviously improves the growth and quality of CNTs, and allows study of the reaction growth of CNTs. This paper demonstrates the effects of compositional ratio of CH 4, CO 2 and N 2 in the mixture gas on the growth of carbon nanotubes under atmospheric conditions. Various substrates of Si and carbon cloth were used to synthesize CNTs by using CH 4–CO 2–N 2 gas sources. A significant difference in morphological structure was observed and analyzed on the different substrates of Si and carbon cloth. By proper adjustment of growth parameters, high quality CNTs were observed on Fe-deposited substrates. The characteristics of the as-grown carbon nanotubes on different substrates were analyzed by SEM, TEM and Raman spectroscopy.