One-pot reduction of graphene oxide at subzero temperatures

Cui, Peng; Lee, Jung-Hyun; Hwang, Eun Young; Lee, Hyoyoung

doi:10.1039/c1cc15569e

Cited by 437 publications

(228 citation statements)

References 34 publications

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“…1B shows the Raman spectra of GO, Pt@rGO and Pd@rGO. The presence of D peak around 1344 cm −1 in GO is due to the lattice distortion of sp 2 bonded carbon atoms after the oxidation of graphite, while G peak is the characteristic peak of sp 2 bonded carbon atoms [36,37]. After the reduction of GO, I D /I G ratio increases from 1 to 1.15 and the G peak is shifted from 1585 to 1581 cm −1 and there is also enhancement in the 2D and S3 peak around 2661 and 2918 cm −1 (ESI-1) which is also a good agreement of GO reduction.…”

Section: Resultsmentioning

confidence: 99%

Rapid reduction of GO by hydrogen spill-over mechanism by in situ generated nanoparticles at room temperature and their catalytic performance towards 4-nitrophenol reduction and ethanol oxidation

Barman

Nanda

2015

Applied Catalysis A: General

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Section: Resultsmentioning

confidence: 99%

Rapid reduction of GO by hydrogen spill-over mechanism by in situ generated nanoparticles at room temperature and their catalytic performance towards 4-nitrophenol reduction and ethanol oxidation

Barman

Nanda

2015

Applied Catalysis A: General

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“…This value suggests again a partial GO reduction, in agreement with the results of TG-MS and XRD measurements, for reduced graphene oxide (rGO). Cui et al 52 found an I D /I G ratio of 1.4, a value of 1.9 was observed for rGO reduced by HI at 100 °C 61 . However, it is difficult to compare the results, since the measurements are often recorded on GO with different edge thickness 60,62 .…”

Section: Samplementioning

confidence: 99%

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Baldino

Sarno

Cardea

et al. 2015

Ind. Eng. Chem. Res.

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(Stefano Cardea) Phone Number: +39089969365; msarno@unisa.it (Maria Sarno) Phone Number: +39089964057.KEYWORDS: Graphene oxide, Cellulose acetate, Nanocomposite, Supercritical CO 2 . ABSTRACTCellulose acetate (CA)/graphene oxide (GO) nanocomposite membranes were generated by an assisted phase inversion process, based on the use of SC-CO 2 as non-solvent, operating at 200 bar and 40 °C; loadings of GO up to 9% w/w were tested. The structures maintained the cellular morphology, characteristics of CA membranes, also at the highest GO loadings used, with a porosity of about 80%, but the presence of GO influenced the pore sizes, that ranged between about 9 and 16 µm. The starting GO and the nanocomposite structures were characterized by the combination of various techniques that evidences as Sulphur and Chlorinated impurities, that were present in the starting GO material, were completely eliminated by the interaction with SC-CO 2 during structures formation; moreover, a partial reduction of GO to graphene was also observed. . Compared to graphene, GO is heavily oxygenated and its basal plane carbon atoms are decorated with epoxide and hydroxyl groups and its edge atoms with carbonyl and carboxyl groups. Hence, GO is highly hydrophilic and the presence of these functional groups reduces interplanar forces, which can improve the interfacial interaction between GO and some polymers and, thus, the dispersion of GO in polymer matrices 2,3 . Many factors can affect the final properties and applications of GO/polymer nanocomposites 4 , among these: kind of GO used, its dispersion state in the polymeric matrix and interfacial interactions, the amount of wrinkling, its network structure in the matrix and its purity.Various attempts have been proposed in the literature to realize GO/polymers composite structures [5][6][7][8][9][10][11][12][13][14][15] . The processes proposed until now (i.e., phase inversion, casting, electrospinning) present several limitations; for example, residues of organic solvents of GO synthesis are typically found at the end of these processes, causing problems, in particular, for biomedical applications. Moreover, a homogeneous distribution of GO in the polymeric matrix is difficult to obtain, since the cohesive forces among GO layers tend to produce restacking. GO composites performance is strongly related to its level of exfoliation (i.e., separation of the layers). Exfoliated GO allows the largest interfacial contact with the polymer matrix, improving the properties of the composites. For this reason, several techniques have been implemented to increase the GO exfoliation degree. In particular, solvent-based exfoliation and thermal exfoliation techniques emerged as two preferred routes for this step [16][17][18][19] . [30][31][32][33] . Due to molecular size of CO 2 and its polarizability, it has the potential to pass through the solid porous layers 34 and, when supercritical conditions are reached, CO 2 diffusivity can favor layers expansion and exfoliation [31][32][33] . It is also possible to...

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“…The TGA scan, figure 7(b), of GO clearly shows that there is a mass loss upon heating. Some of the mass-loss in the temper ature range of 25-165 °C can be attributed to the water loss, CO and CO 2 [45], despite having dried the GO previously. The chemical transition of GO to rGO occurs at approximately T = 165 °C (see figure 7(b)), a temperature which was also observed by Cui et al [45] for this process.…”

Section: Nematic To Isotropic Phase Transitionmentioning

confidence: 99%

“…Some of the mass-loss in the temper ature range of 25-165 °C can be attributed to the water loss, CO and CO 2 [45], despite having dried the GO previously. The chemical transition of GO to rGO occurs at approximately T = 165 °C (see figure 7(b)), a temperature which was also observed by Cui et al [45] for this process. Above 165 °C, the hydrophobic nature of rGO dominates dispersion stability and results in flocculation or aggregation, and consequently rGO does not form LC phases in aqueous media [26].…”

Section: Nematic To Isotropic Phase Transitionmentioning

confidence: 99%

Confinement effects on lyotropic nematic liquid crystal phases of graphene oxide dispersions

et al. 2017

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Graphene oxide (GO) forms well ordered liquid crystal (LC) phases in polar solvents. Here, we map the lyotropic phase diagram of GO as a function of the lateral dimensions of the GO flakes, their concentration, geometrical confinement configuration and solvent polarity. GO flakes were prepared in water and transferred into other polar solvents. Polarising optical microscopy (POM) was used to determine the phase evolution through the isotropic-biphasic-nematic transitions of the GO LC. We report that the confinement volume and geometry relative to the particle size is critical for the observation of the lyotropic phase, specifically, this determines the low-end concentration limit for the detection of the GO LC. Additionally, a solvent with higher polarisability stabilises the LC phases at lower concentrations and smaller flake sizes. GO LCs have been proposed for a range of applications from display technologies to conductive fibres, and the behaviour of LC phase formation under confinement imposes a limit on miniaturisation of the dimensions of such GO LC systems which could significantly impact on their potential applications. LETTEROriginal content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.

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One-pot reduction of graphene oxide at subzero temperatures

Cited by 437 publications

References 34 publications

Rapid reduction of GO by hydrogen spill-over mechanism by in situ generated nanoparticles at room temperature and their catalytic performance towards 4-nitrophenol reduction and ethanol oxidation

Rapid reduction of GO by hydrogen spill-over mechanism by in situ generated nanoparticles at room temperature and their catalytic performance towards 4-nitrophenol reduction and ethanol oxidation

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Confinement effects on lyotropic nematic liquid crystal phases of graphene oxide dispersions

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One-pot reduction of graphene oxide at subzero temperatures

Cited by 437 publications

References 34 publications

Rapid reduction of GO by hydrogen spill-over mechanism by in situ generated nanoparticles at room temperature and their catalytic performance towards 4-nitrophenol reduction and ethanol oxidation

Rapid reduction of GO by hydrogen spill-over mechanism by in situ generated nanoparticles at room temperature and their catalytic performance towards 4-nitrophenol reduction and ethanol oxidation

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO2 Assisted Phase Inversion

Confinement effects on lyotropic nematic liquid crystal phases of graphene oxide dispersions

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Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion