The Interband Importance of the First-order Raman Spectrum of Graphene Oxide
Aïda Varea
a
, Sergi Claramunt
b
, David López-Díaz
c
, M. Mercedes Velázquez
c
, Albert
Cornet
a
, Albert Cirera
a
ª
MIND-IN2UB, Departament d’Enginyeries: Electrònica, Facultat de Física, Universitat de
Barcelona. 08028 Barcelona, Spain
b
Departament d’Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193
Cerdanyola del Vallès, Spain
c
Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de
Salamanca E37008 Salamanca, Spain
Graphene oxide (GO) points to be a suitable material for potential technological and
biological applications
1
due to its oxygen functional groups (O-groups) can attach polymers
or nanoparticles onto the graphitic surface. The amount of O-groups, and thereby GO
properties, can be tuned by reducing processes, for example thermal annealing. Reduction
methods are complex processes that introduce defects on the carbon network. Defects have an
important role that determines the physical and chemical properties of these materials. Taking
into account that the thermal reduction process is still object of discussion, it becomes
necessary to develop an accurate methodology to study it.
In this work Raman spectra of GO and thermal reduced GO have been analyzed in order to
correlate spectral parameters with its structural properties
2
. The chemical composition of
different GOs was determined by Organic Elemental Analysis and the microstructure of
nanocrystals was analyzed by X-ray diffraction. For the Raman analysis in the first-order
region (1000-1800 cm
-1
) five bands (D, D’, G, D’’ and D*) have been located for all spectra.
The band position, intensity ratio and width have been related with oxygen content,
crystallinity and disorder degree of GO and rGO platelets. Results show that the peak
position of the D’’ and D* bands exhibit a pronounced dependence of the oxygen content,
therefore can be used as good parameter to estimate the reduction grade. Also, both, the
I
D’’
/I
G
ratio and the width of the D’’ band decrease when the crystallinity of sheets increases,
while the I
D*
/I
G
ratio decreases when the number of sp
3
bonds of sheets decreases.
Discrepancies between the experimental I
D
/I
G
values and those calculated by both, the
Tuinstra-Koening
3
and Cuesta
4
models when the intensity ratio was calculated from the raw
Raman spectra are now avoided when the spectra are fitted to 5-bands.
[1] X. Sun, Z. Liu, K. Welsher, J.T. Robinson, A. Goodwin, S. Zaric, H. Dai. Nano Res. 1 (2008) 203-212.
[2] S. Claramunt, A. Varea, D. López-Díaz, M.M. Velázquez, A. Cornet, A. Cirera, J. Phys. Chem. C 119 (2015), 18, 10123-
10129.
[3] F. Tuinstra, J.L. Koening, J. Chem. Phys. 53(3) (1970) 1126-1130.
[4] A. Cuesta, P. Dhamelincourt, J. Laureyns, A. Martinez-Alonso, J.M.D. Tascon, J. Mater. Chem. 8(12) (1998), 2875-
2879.
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