Single-Walled Carbon Nanotubes Experimental Gibbs Free Energy Considerations in the Nucleation and Growth of Sinsle-Walled CarbonNanotubes

摘要

Gas feed composition and reaction temperature were varied to identify the thermodynamic threshold conditions for the nucleation and growth of SWNT from methane On supported Fe/Mo catalyst.These reaction conditions closely approximate the pseudoequilibrium conditions that lead to the nucleation and growth of SWNT.These measurements also serve to determine an upper limit of the Gibbs free energy of formation for SWNT.The Gibbs free energy of formation relative to graphite is in good agreement with literature values predicted from simulations for SWNT nuclei containing approximately 80 atoms,while considerably larger than that predicted for bulk(5,5)SWNT.Our estimate over the range 700 to 1000 deg C of 16.1 to 13.9 kJ mol~(-1)falls between the results of these simulations and literature values for diamond.