Interdependency of Gas Phase intermediates and Chemical Vapor Deposition Growth of Single Wall Carbon Nanotubes

The main gas phase intermediates, leading the efficient chemical vapor deposition (CVD) growth of single wall carbon nanotubes (SWCNTs), have been explored through systematic experimental and theoretical studies. The growth efficiencies of the basic radical/neutral species (sp(2) C-2: C2H3/C2H4, sp(2) C-2: C2H3/C2H4 sp(3) C-2: C2H5/C2H6, and sp(3) C-1: CH3/CH4) have been compared by supplying C2H4, C2H6, and CH4, as carbon sources to grow SWCNTs. The gaseous composition of the exhaust was analyzed by an in situ direct sampling mass spectrometric technique using vacuum ultraviolet (VUV)-single photon ionization (SPI)-time-of-flight mass spectrometry (TOFMS). For verification via theoretical prediction, a CHEMKIN calculation was performed. A kinetic analysis of the experimental and theoretical results was compared with thermal decomposition phenomena of the used hydrocarbons, and hence, it was concluded that the key gas phase intermediates produced from the complex gas phase reactions as a final and efficient species capable of initiating the CVD growth of SWCNTs are sp(2)C(2) species, C2H3/C2H4. Additional significance is the production of highly pure SWCNTs from C2H6 since to date production of either only multiwall carbon nanotubes (MWCNTs) or a mixture of MWCNTs and SWCNTs have been reported. This result will be beneficial for selecting suitable hydrocarbons for the efficient growth of SWCNTs.