Increasing the efficiency of single walled carbon nanotube amplification by Fe-Co catalysts through the optimization of CH4/H2 partial pressures

Single walled carbon nanotubes (SWNTs) seeds are grown using Fe-Co nanoparticles on spin-on-glass. The relative efficiency of nucleation and amplification (versus etching) was investigated as a function of the CH(4)/H(2) feedstock ratio and growth temperature. At 900 °C, maximum amplification is obtained with CH(4)/H(2) ratio of 80:20 but 60:40 for nucleation. Amplification is further enhanced at 800 °C, compared with etching dominating at 1000 °C. Amplification of SWNTs is in equilibrium with etching; higher carbon feedstock pressure and decreased temperature increase the rate of amplification; the converse increases etching.