Vertically Aligned, Small-diameter Single-walled Carbon Nanotube Growth from Ir Catalysts

Abstract

We demonstrated that vertically aligned single-walled carbon nanotubes (VA-SWCNTs) can be grown by alcohol catalytic chemical vapor deposition (CVD) using an Ir catalyst in a cold-wall CVD system. VA-SWCNTs were directly grown on SiO₂/Si substrates with neither any buffer layers nor cocatalysts under an ethanol pressure of 1×10^－1 Pa at 800℃. The SWCNT length became longer with increasing growth time and the VA-SWCNT thickness reached ∼4 µm after the growth for 180 min. The diameters of the grown SWCNTs were mainly distributed between 0.8 and 1.2 nm, which is much smaller than those from Fe and Co catalysts. X-ray absorption fine structure spectroscopy result showed that the Ir catalyst retained metallic phase during SWCNT growth, which is in marked contrast with SWCNT growth from Fe and Co catalysts.