Growth of uniform thin-walled carbon nanotubes with spin-coated Fe catalyst and the correlation between the pre-growth catalyst size and the nanotube diameter

Abstract

Single-walled carbon nanotubes (CNTs) and double-walled CNTs with a selectivity of 93% were grown using colloidal solution of 1:1 (v/v) diluted iron nitrate that was spin coated onto a silicon wafer. The average geometric size of the catalyst nanoparticles was 5.08 nm, and the resulting average CNT diameter was 2.19 nm. The diameter of the CNTs was correlated with the geometric size of the pre-growth catalyst nanoparticles. Multi-walled CNTs had a large difference between the size of the catalyst and the nanotube diameter, with a catalyst mean size to CNTs average diameter ratio of 2.89, while the ratio was 2.31 for thin-walled CNTs.