Short communication
Effect of oxygenated functional groups on the photoluminescence properties of graphene-oxide nanosheets

https://doi.org/10.1016/j.mssp.2013.12.015Get rights and content

Abstract

The graphene-oxide (GO) nanosheets were synthesized by varying the degree of oxidation levels in which the observation of different domain size (sp2) of GO and their relationship in photoluminescence (PL) characteristics were investigated. GO consists of two unique carbon domains sp2 and sp3, in which each domain have different charge carrier recombination pathway within the domain. As-prepared GO sample shows the broad emission peak ranging from 350 nm to 600 nm. The PL emission has been tuned from blue to yellow and the emission is directly proportional to corresponding size of sp2 cluster. The Gaussian peaks are centered at different wavelength region for various sizes of sp2 cluster. While increasing the degree of oxidation, the concentration of functional groups are found to be increased resulting the enlargement of sp2 domain size from 15.96 nm to 16.28 nm, due to this, the red shift was observed in the emission spectra. Our results show a basic understanding in photoluminescence characteristics of GO with the effect of oxygenated functional groups.

Introduction

Graphene is a single layer of carbon atoms regularly arranged as a hexagonal honey-comb lattice structure which attracts large attention in recent years due to its high aspect ratio and electron mobility [1], [2]. Due to this unique property, it is used in super capacitor, solar cell, resistive switching and optoelectronic materials. Like graphene, graphene oxide (GO) is also a promising material for selected application like photocatalysis, and super capacitors etc [3], [4], [5]. Ideal graphene is a zero bandgap semiconductor that contains sp2 clusters which are not favorable for luminescence application. Graphene oxide has two different types of carbon domains such as sp2 and sp3. Each domain has different charge transition pathway inside the domain, wherein the photoluminescence (PL) emission depends on the ππ transition within a sp2 matrix [6]. GO is the most important fluorescent compound and its luminescence property strongly depending on sp2/sp3 ratio. The change in sp2/sp3 ratio could play a major role in the development of future GO based optoelectronic devices.

Up to date, PL studies on graphene have been carried out and reported using different types such as oxygen plasma-treated, mechanically exfoliated and single-layer graphene sheets. C.T. Chen et al. studied that PL property can be tunable in GO by using reducing methods [7]. Recently some literatures reported about the PL of pure GO, graphene and modified GO. The modified GO was synthesized by using various techniques such as Mn2+ bonded, different annealing temperature, fluorescence with dyes, functionalized by KOH and HNO3 and their GO quantum dot. L. Annemarie et al. studied the PL behavior in GO and rGO by using sub-pico second spectroscopy.

Based on the literature discussion, sp2/sp3 ratio and sp2 size are very important parameter for PL emission in GO. The sp2/sp3 ratio and size of sp2 can be changed in step by step reduction of GO. During the change of sp2/sp3 ratio in this method, the nature of GO collapses, therefore we need an alternative process in this direction. So for no reports are available on PL in GO with different degree of oxidation levels. We understood that step by step oxidation method can effectively change the sp2 domain size, however, GO nature will not be affected. In this short communication, we mainly focus about the synthesis and investigation of luminescence properties of the GO with different degree of oxidation levels.

Section snippets

Experimental

Different sizes of sp2 cluster of GO nanosheets were synthesized through modified Hummer's method [8]. In shortly, 2 g of graphite powder was added into 50 ml of concentrated H2SO4 in a 500 ml glass beaker, the solution was stirred for 30 min continuously. Then, 2 g of KMnO4 was added slowly into above solution with stirred condition, the mixture was stirred for further 8 h, and during this process 90 ml of double distilled (DD) water was added to this solution. To finish the reaction, 5 ml of H2O2

Results and discussion

Structural studies were investigated by using X-ray diffraction method which is shown in Fig. 1(a). From this figure, it is found that the graphite peak disappears gradually from the sample S1 to S4, and the GO samples show significant change in XRD spectrum which is attributed by the functional groups attached in basal plane of GO sheets during the oxidation process. Furthermore, the interlayer space was found to be increased from 3.3 Å to 8.3 Å which are corresponding to the 2θ value [9]. The ‘d

Conclusion

Graphene oxide with different degree of oxidation was synthesized by modified Hummer's method. As-prepared GO samples were analyzed with XRD, XPS, Raman, FTIR, TEM and PL. The sizes of sp2 clusters of GO were calculated as 15.96 nm, 12.53 nm, 16.09 nm and 16.28 nm. The PL spectra show more than one Gaussian-like peaks. The GO sample with larger degree of oxidation has shown the medium sp2 domain size by showing four individual Gaussian-like peaks compared to other GO samples. The XPS results

Acknowledgements

The author (T.S) acknowledges the Management of Karunya University (KU) for providing Silver Jubilee Fellowship (SJF) scholarship to carry out this research work. We thank to Ms. Kalpana, a Research scholar at Physics Department, for providing support for this research work. Also, all the authors extend their sincere thanks to Mr. A. Raja and Mr. M.B.S. Pravin at Center for Research in Nanotechnology (CRN) at Karunya University for the timely help in doing sample characterization.

References (19)

  • Y. Liu et al.

    Appl. Surf. Sci.

    (2011)
  • Y. Dong et al.

    Carbon

    (2012)
  • G. Xin et al.

    Mater. Lett.

    (2012)
  • B.G. Eda et al.

    Adv. Mater.

    (2009)
  • Z. Luo et al.

    Appl. Phys. Lett.

    (2009)
  • Y.X. Gan et al.

    Nano Lett.

    (2011)
  • K. Krishnamoorthy et al.

    Appl. Phys. Lett.

    (2011)
  • F.A. Chowdhury, T. Morisaki, J. Otsuki, M.S. Alam, Appl. Nanosci.,...
  • M. Li et al.

    J. Mater. Chem.

    (2012)
There are more references available in the full text version of this article.

Cited by (26)

  • Structural and electronic properties of covalently functionalized graphene

    2022, Theoretical and Computational Chemistry
    Citation Excerpt :

    The smaller bandgap of the ECC compared to the boat and twist-boat can be due to the coexistence of sp3- and sp2-hybridized regions. The bandgap calculated with PBE0 for the ECC is 2.82 eV, which is in perfect agreement with the experimental observation of 2.88 eV [95–98]. The experimental values were obtained from photoluminescence peaks for GO.

  • Pitch derived graphene oxides: Characterization and effect on pyrolysis and carbonization of coal tar pitch

    2020, Journal of Analytical and Applied Pyrolysis
    Citation Excerpt :

    The peak near 2300 cm−1 is related to the absorption of CO2 molecules [34], while the peak at 858 cm-1 [35] is indexed to the CC bond in aromatic group. The band peaks near 1568cm−1 appear to represent the carbonyl and carboxyl CO absorption [36]. The absorption bands around 1000–1100 cm−1 are corresponding to the epoxy COC groups [37].

  • A comprehensive study on step-wise surface modification of C<inf>60</inf>: Effect of oxidation and silanization on dynamic mechanical and thermal stability of epoxy nanocomposite

    2016, Materials Chemistry and Physics
    Citation Excerpt :

    Decrease in carbon content for O-Fs and S-Fs indicates possibility of removing strong disordered structure of amorphous carbon due to HNO3 treatment that might be existing in P-Fs. On the other hand, increase in oxygen content for O-Fs and S-Fs is predictive for attachment of oxygenated functional elemental groups [46]. In case of S-Fs, increase in oxygen content and generation of new deceptive peak of Si at 1.7 keV indicates covalent attachment of siloxane group through the possible reaction mechanism schematically demonstrated in Fig. 1.

  • Visible-light driven photocatalytic degradation of methylene-violet by rGO/Fe<inf>3</inf>O<inf>4</inf>/ZnO ternary nanohybrid structures

    2016, Journal of Alloys and Compounds
    Citation Excerpt :

    One step hydrothermal method was carried out to prepare the rGO/Fe3O4/ZnO ternary nanohybrid. Firstly, GO was synthesized by modified Hummers method as reported in our previous report [23]. For preparing ternary nanohybrid, Fe3O4 nanorods were prepared by hydrothermal method and a detailed preparation method is given in supporting information as Section 1.

View all citing articles on Scopus
View full text