Graphite Oxide:  Chemical Reduction to Graphite and Surface Modification with Primary Aliphatic Amines and Amino Acids

Bourlinos, Athanasios B.; Gournis, Dimitrios; Petridis, D.; Szabó, Tamás; Szeri, and Anna; Dékány, Imre

doi:10.1021/la026525h

Cited by 1,151 publications

(726 citation statements)

References 12 publications

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“…The surface oxidation disrupts the p-conjugated network, rendering the nanoribbons and graphite oxide poorly conductive. Hydrazine (N 2 H 4 ) reduction of graphite oxide 25 is known to provide a means of restoring conjugation and, thus, some of the conductivity, to form chemically converted graphene (CCG) [25][26][27][28] . The structure of CCG is thought to be a patchwork of intact graphene islands interspersed with regions of tetrahedral sp 3 -hybridized carbon atoms due to incomplete reduction and incomplete re-aromatization; therefore, the electrical conductivity is not as high as that found in the original graphite 26 .…”

mentioning

confidence: 99%

Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons

Kosynkin¹,

Higginbotham²,

Sinitskii³

et al. 2009

Nature

3,271

2,738

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Graphene, or single-layered graphite, with its high crystallinity and interesting semimetal electronic properties, has emerged as an exciting two-dimensional material showing great promise for the fabrication of nanoscale devices [1][2][3] . Thin, elongated strips of graphene that possess straight edges, termed graphene ribbons, gradually transform from semiconductors to semimetals as their width increases 4-7 , and represent a particularly versatile variety of graphene. Several lithographic 7,8 , chemical 9-11 and synthetic 12 procedures are known to produce microscopic samples of graphene nanoribbons, and one chemical vapour deposition process 13 has successfully produced macroscopic quantities of nanoribbons at 950 6C. Here we describe a simple solution-based oxidative process for producing a nearly 100% yield of nanoribbon structures by lengthwise cutting and unravelling of multiwalled carbon nanotube (MWCNT) side walls. Although oxidative shortening of MWCNTs has previously been achieved 14 , lengthwise cutting is hitherto unreported. Ribbon structures with high water solubility are obtained. Subsequent chemical reduction of the nanoribbons from MWCNTs results in restoration of electrical conductivity. These early results affording nanoribbons could eventually lead to applications in fields of electronics and composite materials where bulk quantities of nanoribbons are required [15][16][17] .We obtained oxidized nanoribbons by suspending MWCNTs in concentrated sulphuric acid followed by treatment with 500 wt% KMnO 4 for 1 h at room temperature (22 uC) and 1 h at 55-70 uC (Methods). After isolation, the resulting nanoribbons were highly soluble in water (12 mg ml 21 ), ethanol and other polar organic solvents. The opening of the nanotubes appears to occur along a line, similar to the 'unzipping' of graphite oxide 18,19 , affording straightedged ribbons. This could occur in a linear longitudinal cut (Fig. 1a) or in a spiralling manner, depending upon the initial site of attack and the chiral angle of the nanotube. Although depicted in Fig. 1a as occurring on the mid-section of the nanotube rather than at one end, the location of the initial attack is not known.The mechanism of opening is based on previous work on the oxidation of alkenes by permanganate in acid. The proposed first step in the process is manganate ester formation (2, Fig. 1b) as the ratedetermining step, and further oxidation is possible to afford the dione (3, Fig. 1b) in the dehydrating medium 20 . Juxtaposition of the buttressing ketones distorts the b,c-alkenes (red in 3), making them more prone to the next attack by permanganate. As the process continues, the buttressing-induced strain on the b,c-alkenes lessens because there is more space for carbonyl projection; however, the bond-angle strain induced by the enlarging hole (or tear if originating from the end of the nanotube) would make the b,c-alkenes (4, Fig. 1b) increasingly reactive. Hence, once an opening has been initiated, its further opening is enhanced relative to an unopened ...

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mentioning

confidence: 99%

Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons

Kosynkin¹,

Higginbotham²,

Sinitskii³

et al. 2009

Nature

3,271

2,738

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“…1d), which is in agreement with previously reported XRD data for similar heavily oxidized GO materials. 29,32,[52][53][54][55][56] The GO platelets were dispersed in distilled water to yield a 0.05 mg ml À1 solution, which was drop-cast on a modied KAMINA multisensor chip (Fig. 2a).…”

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Highly selective gas sensor arrays based on thermally reduced graphene oxide

et al. 2013

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“…Understanding the reduction process is not only of importance from a fundamental point of view but is also key to the improvement and exploitation of reduced GO (rGO) on industrial scales. Over the years, various procedures have been reported; the reactions range from the widely used sodium borohydride 13 and hydrazine 14,15 methods to catalytic 16 , plasma-induced 17 , thermally induced [18][19][20] and photoinduced reduction [21][22][23] . Although each of these methods has its own merits, light-induced reduction of GO promises to be a rapid and facile way of producing rGO while avoiding the use of harsh chemicals.…”

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confidence: 99%

Revealing the ultrafast process behind the photoreduction of graphene oxide

et al. 2013

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Effective techniques to reduce graphene oxide are in demand owing to the multitude of potential applications of this two-dimensional material. A very promising green method to do so is by exposure to ultraviolet irradiation. Unfortunately, the dynamics behind this reduction remain unclear. Here we perform a series of transient absorption experiments in an effort to develop and understand this process on a fundamental level. An ultrafast photoinduced chain reaction is observed to be responsible for the graphene oxide reduction. The reaction is initiated using a femtosecond ultraviolet pulse that photoionizes the solvent, liberating solvated electrons, which trigger the reduction. The present study reaches the fundamental time scale of the ultraviolet photoreduction in solution, which is revealed to be in the picosecond regime.

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Graphite Oxide: Chemical Reduction to Graphite and Surface Modification with Primary Aliphatic Amines and Amino Acids

Cited by 1,151 publications

References 12 publications

Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons

Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons

Highly selective gas sensor arrays based on thermally reduced graphene oxide

Revealing the ultrafast process behind the photoreduction of graphene oxide

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