Table 1.

Characterization techniques of CNTs.

Characterization Techniques	Major Aims	References
SEM	Morphological analysis (diameter, length, defects and purity), arrangement state	[30]
TEM	Morphological analysis (diameter and defects) Characterization SWCNTs and MWCNTs MWCNTs internal microscopy (number of layers and distance between them)	[30]
Energy dispersive spectroscopy (EDS)	Elemental composition, functionalization	[31]
RS	Characterization SWCNTs and MWCNTs Quality and purity SWCNTs mean diameter and chirality	[33]
Fourier transform infrared spectroscopy (FT-IR)	Functionalization	[31]
Ultraviolet-visible spectroscopy (UV-Vis)	CNTs diameter, length and purity Dispersion state	[30]
Fluorescence spectroscopy (FS)	Semiconducting SWCNTs diameter and chirality	[38]
XPS	Elemental composition, functionalization	[36]
TG	Purity, functionalization	[37]
Boehm titration	Number of oxygen-containing functional groups	[39]