Control of iron nanoparticle size by manipulating PEG-ethanol colloidal solutions and spin-coating parameters for the growth of single-walled carbon nanotubes

Iron catalyst nanoparticles were prepared on silicon wafers by spin-coating colloidal solutions containing iron nitrate,polyethylene glycol(PEG) and absolute ethanol.The effects of various spin-coating conditions were investigated.The findings showed that the size of the iron particles was governed by the composition of the colloidal solution used and that a high angular speed was responsible for the formation of a thin colloidal film.The effect of angular acceleration on the size and distribution of the iron particles were found to be insignificant.It was observed that a longer spin-coating duration provoked the agglomeration of iron particles,leading to the formation of large particles.We also showed that single-walled carbon nanotubes could be grown from the smallest iron catalyst nanoparticles after the chemical vapor deposition of methane.