Synthesis of high-purity few-walled carbon nanotubes from ethanol/methanol mixture

Few-walled carbon nanotubes (FWNTs) can be synthesized in a simple chemical vapor deposition (CVD) system using ethanol as the carbon source. However, the raw materials always contain a significant amount of impurities due to decomposition of ethanol molecules on the catalyst support, which makes the purification difficult, resulting in a low yield of purified nanotubes. Here, we report that with use of an ethanol/methanol mixture as the carbon source, FWNTs with high purity can be prepared. Through a simple purification process, highly pure FWNTs can be obtained. A systematic study of the effect of ethanol/methanol ratio revealed the origin for the improved purity of the sample. Under the growth conditions studied, ethanol acted as the carbon source while methanol acted as "carbonaceous impurity remover" to remove the impurities deposited on the MgO support and hindered the formation of such impurities.