A study of graphenes prepared by different methods: characterization, properties and solubilization

Subrahmanyam, K. S.; Vivekchand, S. R. C.; Govindaraj, A.; Rao, C. N. R.

doi:10.1039/b716536f

Cited by 545 publications

(334 citation statements)

References 17 publications

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“…From the Z-scan experiments at intensity ~16 GW/cm 2 we observe a saturable absorption behavior. The graphene samples studied by us show positive change in the differential transmission of the probe in the pump-probe experiment along with two component relaxation dynamics in the range of 130-330 fs and 3.5-4.9 ps associated with the carrier-carrier and carrier-phonon scattering processes in graphene.Solution-phase and chemical exfoliation techniques provide a low-cost, high-yield method for mass production of graphene [8][9][10][11][12][13][14] as compared to commonly used methods such as micromechanical cleavage and epitaxial growth. For our study, graphene suspensions were prepared in three different solvents, distilled water, dimethylformamide (DMF) and tetrahydrofuran (THF).…”

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confidence: 99%

“…Solution-phase and chemical exfoliation techniques provide a low-cost, high-yield method for mass production of graphene [8][9][10][11][12][13][14] as compared to commonly used methods such as micromechanical cleavage and epitaxial growth. For our study, graphene suspensions were prepared in three different solvents, distilled water, dimethylformamide (DMF) and tetrahydrofuran (THF).…”

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confidence: 99%

“…The concentration of the GO and G-H 2 O suspensions were ~80 µg/ml and 60 µg/ml, respectively. Suspensions of functionalized graphene in DMF and THF were obtained and characterized as described in the literature [13,14]. In the later samples, the suspensions contained few-layer graphene flakes.…”

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Femtosecond carrier dynamics and saturable absorption in graphene suspensions

Kumar

Anija

Kamaraju

et al. 2009

Applied Physics Letters

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210

147

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Nonlinear optical properties and carrier relaxation dynamics in graphene, suspended in three different solvents, are investigated using femtosecond (80 fs pulses) Z-scan and degenerate pumpprobe spectroscopy at 790 nm. The results demonstrate saturable absorption property of graphene with a nonlinear absorption coefficient, β, of ~2 to 9x10 -8 cm/W. Two distinct time scales associated with the relaxation of photoexcited carriers, a fast one in the range of 130-330 fs (related to carriercarrier scattering) followed by a slower one in 3.5-4.9 ps range (associated with carrier-phonon scattering) are observed.Graphene is a two-dimensional carbon nanomaterial which has received tremendous interest in recent years owing to its various remarkable properties and applications in modern electronics and photonics [1,2]. Ultrafast degenerate and nondegenerate pump-probe measurements on single and multilayer epitaxial [3,4] or exfoliated [5] graphenes deposited on a substrate have shown two types of dynamics of the carriers: a fast component of the order of ~100 fs attributed to the intraband carrier-carrier scattering and a slower component ~2 ps associated with carrierphonon scattering. In the degenerate pump-probe studies on single and multilayer graphene films grown on a SiC substrate using 85 fs laser pulses centered at 790 nm, a positive change in the transient differential transmission of the probe was observed with two relaxation times, the faster one in the range of 70-120 fs and a slower one between 0.4-1.7 ps [3]. Similar carrier relaxation dynamics was obtained in the nondegenerate pump-probe experiments on exfoliated graphene films on SiO 2 /Si substrate [5]. On a few layer thick graphene film on SiC, nondegenerate pump-probe experiments [4] using 800 nm pump showed that the sign of the differential transmission signal is positive over the entire probe spectral range of 1.1 to 2.6 µm but becomes negative after 2 ps if the probe wavelength falls between 1.78 and 2.35 µm. The initial positive part of the signal within 150 fs has been described in terms of thermalization and emission of high energy-phonons followed by a slow decay of the order of a few ps determined by electron-acoustic phonon scattering. Nonlinear optical properties of graphene have been reported recently in the nanosecond (ns) and picosecond (ps) regimes [6,7]. Using 35 ps laser pulses centered at 532 nm, it has been shown that the nonlinear response of graphene oxide suspensions changes from saturable absorption at low intensity (2.1 GW/cm 2 ) to reverse saturable absorption or optical limiting at higher intensities (>4.5 GW/cm 2 ) [6]. In comparison, in the ns regime suspensions of graphene oxide and functionalized graphene in dimethylformamide showed optical limiting property at all values of intensities above 0.6 GW/cm 2 [6,7].We have carried out femtosecond (80 fs) Z-scan and degenerate pump-probe experiments at 790 nm to study the nonlinear optical response and carrier dynamics in colloidal suspensions of graphene which have not been invest...

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Femtosecond carrier dynamics and saturable absorption in graphene suspensions

Kumar

Anija

Kamaraju

et al. 2009

Applied Physics Letters

Self Cite

210

147

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show abstract

“…The growth of graphene cannot be described by a universal mechanism with specific routes and conditions. Actually, there is a variety of synthesis strategies and growth modes 7 . A good mechanism for its growth is the use of metal catalysts on which free carbon radicals are formed, carbon is dissolved in the catalyst, and finally precipitates and crystallizes at the surface 8 .…”

Section: Introductionmentioning

confidence: 99%

Characterization of Thin Carbon Films Produced by the Magnetron Sputtering Technique

et al. 2016

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“…Various methods such as exfoliation [1], thermal decomposition of SiC [10], chemical vapour deposition (CVD) on nickel [11] and copper [12] substrates, molecular beam deposition [13], unzipping carbon nanotubes [14], sodium ethanol pyrolysis [15], electron beam irradiation of PMMA * E-mail: ravinj2001@yahoo.co.in nanofibres [16], arc discharge of graphite [17], thermal fusion of PAHs [18] and conversion of nanodiamond [19] have been reported and reviewed.…”

Section: Introductionmentioning

confidence: 99%

CVD synthesis of graphene nanoplates on MgO support

Jugade

Sharma

Gokhale

2014

Materials Science-Poland

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Synthesis of graphene directly on MgO has been carried out and the structural properties of the obtained material have been investigated. Few-layered graphene was produced by simple thermal decomposition of methane over MgO powder at 950°C in a CVD reactor. The samples were purified by 10 N HNO 3 treatment, and studied by TEM, Raman spectroscopy, EDAX and SEM. TEM clearly indicated the formation of graphene. EDAX showed that the purified sample contained only carbon and no traces of MgO. The characteristic Raman features of graphene were also seen as D-band at 1316 cm −1 , G-band at 1602 cm −1 , and a small 2D-band at 2700 cm −1 in the Raman spectra. The strong D-band suggests that the graphene possess large number of boundary defects. The small 2D-band indicates the formation of few-layered graphene.

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A study of graphenes prepared by different methods: characterization, properties and solubilization

Cited by 545 publications

References 17 publications

Femtosecond carrier dynamics and saturable absorption in graphene suspensions

Femtosecond carrier dynamics and saturable absorption in graphene suspensions

Characterization of Thin Carbon Films Produced by the Magnetron Sputtering Technique

CVD synthesis of graphene nanoplates on MgO support

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