Surfactant effect of sulfuric acid on the exfoliation of bilayer graphene

Ayala, Isabe G.; Cordero, Nicolás A.; Alonso, J. A.

doi:10.1103/physrevb.84.165424

Cited by 17 publications

(14 citation statements)

References 43 publications

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“…This can be explained since sulfuric acid molecules produced in the etching process by (NH 4 ) 2 S 2 O 8 are also reported to be absorbed by graphene. 28 Fermi levels for all the samples obtained here are on the order of several hundreds of meV. These values agree with the previously reported values for CVD-grown and transferred graphene.…”

Section: Resultssupporting

confidence: 92%

Effects of etchants in the transfer of chemical vapor deposited graphene

Wang

Yang

Vajtai

et al. 2018

Journal of Applied Physics

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The quality of graphene can be strongly modified during the transfer process following chemical vapor deposition (CVD) growth. Here, we transferred CVD-grown graphene from a copper foil to a SiO 2 /Si substrate using wet etching with four different etchants: HNO 3 , FeCl 3 , (NH 4) 2 S 2 O 8 , and a commercial copper etchant. We then compared the quality of graphene after the transfer process in terms of surface modifications, pollutions (residues and contaminations), and electrical properties (mobility and density). Our tests and analyses showed that the commercial copper etchant provides the best structural integrity, the least amount of residues, and the smallest doping carrier concentration.

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Section: Resultssupporting

confidence: 92%

Effects of etchants in the transfer of chemical vapor deposited graphene

Wang

Yang

Vajtai

et al. 2018

Journal of Applied Physics

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“…We have used the Density Functional Theory (DFT) formalism [47] within the Local Density Approximation (LDA) [48,49] as implemented in the Gaussian 09 [50] and Gaussian 16 [51] suites of programs. We have selected DFT for its balance between accuracy and computational effort, and have chosen LDA because it gives better results than gradient corrected approximations (GGAs) for graphitic systems [52][53][54] and because it has been previously used to successfully study the interaction between carbon nanostructures and several small molecules and atoms [55][56][57][58][59][60] as well as-very recently-graphene nanoribbons [61]. We have selected the 6-31G** basis set [62][63][64][65][66][67] that adds to the 6-31G set d-type and p-type Cartesian-Gaussian polarization functions and is commonly used for carbon nanostructures calculations.…”

Section: Methodsmentioning

confidence: 99%

Quantum Revivals in Curved Graphene Nanoflakes

2022

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Graphene nanostructures have attracted a lot of attention in recent years due to their unconventional properties. We have employed Density Functional Theory to study the mechanical and electronic properties of curved graphene nanoflakes. We explore hexagonal flakes relaxed with different boundary conditions: (i) all atoms on a perfect spherical sector, (ii) only border atoms forced to be on the spherical sector, and (iii) only vertex atoms forced to be on the spherical sector. For each case, we have analysed the behaviour of curvature energy and of quantum regeneration times (classical and revival) as the spherical sector radius changes. Revival time presents in one case a divergence usually associated with a phase transition, probably caused by the pseudomagnetic field created by the curvature. This could be the first case of a phase transition in graphene nanostructures without the presence of external electric or magnetic fields.

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“…This suggests that for GIC formation and oxidation the initial ability of the sulfuric acid to penetrate the graphite lattice is less important, but the mobility of the sulfuric acid between extended graphite sheets is the more decisive factor. To explore this idea, a series of ab initio molecular dynamics (MD) simulations were performed in order to determine the interaction of confined sulfuric acid molecules with the graphite lattice 36 and to probe how their mobility depends on the graphite stacking and the GIC oxidation state.…”

Section: Resultsmentioning

confidence: 99%

Effect of friction on oxidative graphite intercalation and high-quality graphene formation

et al. 2018

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Oxidative wet-chemical delamination of graphene from graphite is expected to become a scalable production method. However, the formation process of the intermediate stage-1 graphite sulfate by sulfuric acid intercalation and its subsequent oxidation are poorly understood and lattice defect formation must be avoided. Here, we demonstrate film formation of micrometer-sized graphene flakes with lattice defects down to 0.02% and visualize the carbon lattice by transmission electron microscopy at atomic resolution. Interestingly, we find that only well-ordered, highly crystalline graphite delaminates into oxo-functionalized graphene, whereas other graphite grades do not form a proper stage-1 intercalate and revert back to graphite upon hydrolysis. Ab initio molecular dynamics simulations show that ideal stacking and electronic oxidation of the graphite layers significantly reduce the friction of the moving sulfuric acid molecules, thereby facilitating intercalation. Furthermore, the evaluation of the stability of oxo-species in graphite sulfate supports an oxidation mechanism that obviates intercalation of the oxidant.

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Surfactant effect of sulfuric acid on the exfoliation of bilayer graphene

Cited by 17 publications

References 43 publications

Effects of etchants in the transfer of chemical vapor deposited graphene

Effects of etchants in the transfer of chemical vapor deposited graphene

Quantum Revivals in Curved Graphene Nanoflakes

Effect of friction on oxidative graphite intercalation and high-quality graphene formation

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