Metal-Catalyst-Free Growth of Single-Walled Carbon Nanotubes

We present a metal-catalyst-free CVD process for the high-efficiency growth of single-walled carbon nanotubes (SWNTs) on surface. By applying a 30-nm-thick SiO2 sputtering deposited Si or Si/SiO2 wafer as substrate and CH4 as a carbon source, dense and uniform SWNT networks with high quality can be obtained without the presence of any metal species. Moreover, a simple patterned growth approach, using a scratched Si/SiO2 wafer as substrate, is also presented for the growth of SWNTs with good position controllability. Our finding of the growth of SWNTs via a metal-catalyst-free process will provide valuable information for understanding the growth mechanism of SWNTs in-depth, which accordingly will facilitate the controllable synthesis and applications of carbon nanotubes.