Electron Density Modification of Single Wall Carbon Nanotubes (SWCNT) by Liquid-Phase Molecular Adsorption of Hexaiodobenzene

• Main Authors: Hirofumi Kanoh, Akira Sakuma, Hiroto Komatsu, Sumio Iijima, Motoo Yumura, Katsumi Kaneko, Kenji Hata, Tomonori Ohba, Mingxia Lu
• Format: Article
• Language: English
• Published: MDPI AG 2013-02-01
• Series: Materials
• Subjects: single wall carbon nanotube; hexaiodobenzene; adsorption; charge transfer
• Online Access: http://www.mdpi.com/1996-1944/6/2/535

Electron density of single wall carbon nanotubes (SWCNT) is effectively modified by hexaiodobenzene (HIB) molecules using liquid-phase adsorption. UV-Vis-NIR absorption spectra of the HIB-adsorbed SWCNT, especially in the NIR region, showed a disappearance of S11 transitions between the V1 valance band and the C1 conduction band of van Hove singularities which can be attributed to the effective charge transfer between HIB and the SWCNT. The adsorption of HIB also caused significant peak-shifts (lower frequency shift around 170 cm−1 and higher shift around 186 cm‑1) and an intensity change (around 100–150 cm−1 and 270–290 cm−1) in the radial breathing mode of Raman spectra. The charge transfer from SWCNT to HIB was further confirmed by the change in the C1s peak of X-ray photoelectron spectrum, revealing the oxidation of carbon in SWCNT upon HIB adsorption.