Spray coating as a simple method to prepare catalyst for growth of diameter-tunable single-walled carbon nanotubes

Spray coating is proposed as an optional wet method for preparing nano-sized particles suitable for the growth of single-walled carbon nanotubes (SWCNTs). The obtained SWCNT films are characterized by Raman spectroscopy and electron microscopy, and are confirmed to be comparable to SWCNTs produced by the conventional dip-coating process in terms of crystallinity, tube diameter and carbon yield. The mean diameter of SWCNTs can be effectively reduced from 1.85 to 1.35 nm by prolonging the deposition of Mo. In addition, spray coating allows catalyst preparation on supports other than flat wafers, as demonstrated by the synthesis of high-quality SWCNTs on Al₂O₃ fiber and quartz wool supports.