Manipulation of the catalyst-support interactions for inducing nanotube forest growth

We show how an oxidative pretreatment of Fe, Co, or Ni growth catalyst on SiO2 support can be used to switch the growth mode of carbon nanotubes from tip growth to root growth, thus favoring the growth of dense, vertically aligned nanotube forests. The oxidative treatment creates a strong catalyst-support interaction at the catalyst-silica interface, which limits the surface diffusion and sintering of the catalyst nanoparticles and binds the catalyst to the SiO2 surface. This shows that the alignment and growth mode of nanotubes can be controlled, increasing the range of support materials giving dense nanotube forests. (c) 2011 American Institute of Physics. [doi:10.1063/1.3549813]