Optical spectroscopic studies of aqueous suspensions and composites of SWNT
Résumé
We discuss the intrinsic optical spectroscopy (UV-vis-NIR absorption, Raman and photoluminescence)
signatures of single layer graphene (SLG) and single wall carbon nanotubes (SWNT) dispersed in
degassed water without additives, so called "eau de graphene" (EdN) [1-3] and ‘‘eau de nanotubes”
(EdN) [4].
The most characteristic signature of SLG in EdG is a narrow and symmetric 2D band with a width
depending on processing conditions [2,3]. The position of the G and 2D bands indicate moderate biaxial
compressive strain and weak n doping. The intensity of the D band and the width of the G band are
discussed in terms of point-defect density and flake size. We show that point defects can be easily cured
by preparing thin films from EdG and annealing at 800°C.
The signatures of SWNT in EdN are found to be very close to those of SWNT dispersed in aqueous
suspensions stabilized with surfactants [4]. Absorption peaks appear to be even slightly better resolved
for EdN, suggesting sharper excitonic resonances, which is also supported by the Raman data. These
signatures support that SWNT are dispersed as individuals in EdN, in a similar way SLG are
dispersable in EdG [1-3].
[1] G. Bepete et al, Nat. Chem. 2016, DOI 10.1038/NCHEM2669
[2] G. Bepete et al, J. Phys. Chem. C 2016, 120 (49), 28204–28214.
[3] G. Bepte et al, Phys. Stat. Solidi 2016, 10 (12), 895-899.
[4] G. Bepete et al, to be published