16.4 Characterization Techniques of Graphene-Based Nanostructures

Characterization of graphene is crucial to investigate the number of layers and defects

and to tailor its properties regarding the intended applications. Characterization en­

compasses both microscopic as well as spectroscopic measurements. The most convincing

approaches embrace Raman spectroscopy, X-ray photoelectron spectroscopy (XPS),

Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray absorp­

tion near edge structure (XANES), X-ray absorption fine structure (XAFS), atomic force

microscopy (AFM), scanning electron microscopy (SEM), transmission electron micro­

scopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-

visible spectroscopy (UV-vis), X-ray fluorescence (XRF), inductively coupled plasma mass

spectrometry (ICP), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET),

and scanning tunneling microscopy (STM) [29–31]. Microscopic characterizations

techniques include optical microscopy, scanning electron microscopy (SEM), TEM, and

AFM sheen light on the morphology, flake size, and the number of layers. Figure 16.4

shows the schematic representation of various characterization techniques adopted for

graphene-based nanomaterials.

The crystal structure of graphene can be investigated through an optical method known

as Raman spectroscopy. This method delivers an idea about the hybridization of the car­

bonaceous structure as well as the level of disorder and number of layers present in gra­

phene. Raman spectroscopy is a simple, fast, and non-invasive technique, which is highly

sensitive to minute changes in the structure and by this technique, vibrant information

on the number of layers, defects, and functionalization of graphene can be achieved.

Two characteristic bands namely the D and G bands were observed in the Raman spectrum.

The D peak (~1,335 cm⁻¹) was attributed to the defects and disorder while the G band

(~1,593 cm⁻¹) was ascribed to the first-order scattering of the E2g phonon of sp2 carbons

atoms and the intensity ratio of both peaks (ID/IG), usually used to qualitatively compare

the density of structural defects present in graphene.

Fourier transform infrared spectroscopy (FTIR) is another most accessible and fastest

technique, which is complementary to Raman spectroscopy to identify the type of oxygen

functionalities and bonding configuration existing in graphene, GO, and its derivatives.

FIGURE 16.3

Potential precursors adopted for the synthesis of graphene.

Graphene Nanostructures

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