Direct Growth of Single-Walled Carbon Nanotubes without Metallic Residues by Using Lead as a Catalyst

The IVA group metal Pb was found to be an efficient catalyst for the chemical vapor deposition (CVD) growth of single-walled carbon nanotubes (SWCNTs) under suitable conditions. Especially the volatility of Ph made it feasible to realize the direct growth of SWCNTs with no metallic catalyst residues. Three methods including a low gas flow process, a fast-heating process, and a polymer-assisted process were used to control the volatility of lead at a suitable level. Both random SWCNT networks and horizontally aligned SWCNT arrays were efficiently grown on silicon wafers. The density of the SWCNT arrays can be altered by the CVD conditions. The electrical transport measurements for single tubes show that the produced SWCNTs are of high quality. These directly prepared SWCNTs with no metallic impurities will greatly benefit the study of the intrinsic properties of SWCNTs and are very important for making use of SWCNTs in nanodevices and in biological systems.