Temperature-dependent selective nucleation of single-walled carbon nanotubes from stabilized catalyst nanoparticles

The utilization of metal nanoparticles supported on oxides substrate as a catalyst for rational single-walled carbon nanotube (SWCNT) growth is hindered by particle coarsening at high synthesis temperature, despite many empirical advances in supported catalyst design. In this study, a newly developed MgO-supported cobalt (Co-MgO) catalyst affords the formation of well-stabilized Co nanoparticles upon reduction, which is attributed to the electronic metal-support interaction and electrostatic stabilization at the Co-MgO interface. The highly stabilized Co nanoparticles led to the predominant growth of (6, 5) SWCNTs at 700 °C by CO disproportionation and the major SWCNT species was found to be (7, 5) SWCNTs at a reaction temperature of 800 °C. The temperature-dependent selective growth of the two SWCNT species was found, by density functional theory calculation, to be strongly correlated with the change of the relative thermodynamic stability of the SWCNT nuclei in the chirality assigning process at different temperatures.