Direct Measurement of the Surface Energy of Graphene

Engers, Christian D. van; Cousens, Nico E. A.; Babenko, Vitaliy; Britton, Jude; Zappone, Bruno; Grobert, Nicole; Perkin, Susan

doi:10.1021/acs.nanolett.7b01181

Cited by 103 publications

(89 citation statements)

References 45 publications

(85 reference statements)

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“…The pressure of entrapped water in this case was calculated to be in the order of 1 GPa with the liquid thickness of 11.5 Å, equal to three layers of water molecules. This high pressure is also in accordance with the Laplace pressure of liquid films

Δ P_{normalg} = \frac{2 γ_{normalg}}{R}

, where Δ P g is the pressure differential across a graphene membrane, γ g the interfacial energy of water on graphene (90 mJ m −2 ) and R the radius of curvature of the GLC (Figure d) . However, the alleged formation of ice between graphene sheets, a.k.a.…”

Section: Thermodynamic State Of Glcsupporting

confidence: 86%

“…This high pressure is also in accordance with the Laplace pressure of liquid films , where ΔP g is the pressure differential across a graphene membrane, γ g the interfacial energy of water on graphene (90 mJ m −2 ) and R the radius of curvature of the GLC (Figure 3d). [68,69] However, the alleged formation of ice between graphene sheets, a.k.a. squared ice, was challenged due to similarities with the crystal structure of salt remnants and lack of EELS data to exclude the possibility of other contaminants, such as NaCl.…”

Section: Thermodynamic State Of Glcmentioning

confidence: 99%

“…In situ EELS and Raman spectroscopy along with GLC HRTEM will play a key role in the near future to validate longstanding theories on liquid behavior under nanoconfinement. Graphene possesses relatively low surface energy (120 mJ m −2 ) www.advancedsciencenews.com www.small-methods.com Small Methods 2019, 3,1900026 with hydrophobic chemistry, [68,137,139] which brings the necessity of graphene surface modification for complex amphiphilic samples, like cell membranes. [140] Functionalizing graphene with hydrophilic chemical agents like hydroxyl and amine or hybridizing graphene with high hysteresis 2D nanomaterials (e.g., h-BN) manipulates the surface energy of the graphene that allowing to tackle capillary systems with different content and dynamic characteristics.…”

Section: Understanding Nanoconfinement Effects In Glcsmentioning

confidence: 99%

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Advances in Graphene‐Based Liquid Cell Electron Microscopy: Working Principles, Opportunities, and Challenges

2019

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Imaging materials and biological structures in a liquid environment pose a significant challenge for conventional transmission electron microscopy (TEM) due to stringent requirement of ultrahigh vacuum design in the microscope column. The most recent liquid‐cell TEM technique, graphene liquid‐cell (GLC) microscopy, employs only layers of graphene to encapsulate liquid specimens. Recent efforts with GLC–TEM have demonstrated superior imaging resolution of beam‐sensitive specimens. Herein, the parameters that affect the quality of GLC analysis, including the graphene transfer onto TEM grids, are reviewed. Several important factors that affect the in situ TEM imaging of specimens, including the variations in GLC geometries and capillary pressure are discussed. The interaction between the electron beam and the liquid along with the possibility for artifacts or the formation of radical ions is also highlighted in this review. The scientific discoveries enabled by GLC–TEM in the areas of nucleation and growth of crystals, corrosion, battery science, as well as high‐resolution imaging of organelles and proteins are also briefly discussed. Finally, possible future research directions of GLC–TEM and the associated challenges are discussed. The synergistic effort to accomplish the proposed research directions has the potential to yield new discoveries in both materials and life sciences.

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Δ P_{normalg} = \frac{2 γ_{normalg}}{R}

Section: Thermodynamic State Of Glcsupporting

confidence: 86%

Section: Thermodynamic State Of Glcmentioning

confidence: 99%

Section: Understanding Nanoconfinement Effects In Glcsmentioning

confidence: 99%

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Advances in Graphene‐Based Liquid Cell Electron Microscopy: Working Principles, Opportunities, and Challenges

2019

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“…In addition to the formation of individual AlN islands, it is also possible for the AlN islands to merge with their nearest vicinity to form coalesced AlN islands (e.g., marked with the orange contours). A tendency for AlN to form an island (and its cluster formation) instead of a thin-film could be caused by the extremely low surface energy (lack of dangling bonds/chemical inertness) of graphene 18 , which promotes the high surface tension on graphene surface. In addition, the lack of dangling bonds in these graphene surface areas hampers the AlN nucleation process to form a continuous thin-film structure, contrary to the formation of high-density AlN nanostructures in which the dangling bonds are provided by the defects along the graphene line defects.…”

Section: Resultsmentioning

confidence: 99%

The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene

Mulyo

Rajpalke

Vullum

et al. 2020

Sci Rep

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GaN nanocolumns were synthesized on single-layer graphene via radio-frequency plasma-assisted molecular beam epitaxy, using a thin migration-enhanced epitaxy (MEE) AlN buffer layer as nucleation sites. Due to the weak nucleation on graphene, instead of an AlN thin-film we observe two distinguished AlN formations which affect the subsequent GaN nanocolumn growth: (i) AlN islands and (ii) AlN nanostructures grown along line defects (grain boundaries or wrinkles) of graphene. Structure (i) leads to the formation of vertical GaN nanocolumns regardless of the number of AlN MEE cycles, whereas (ii) can result in random orientation of the nanocolumns depending on the AlN morphology. Additionally, there is a limited amount of direct GaN nucleation on graphene, which induces nonvertical GaN nanocolumn growth. The GaN nanocolumn samples were characterized by means of scanning electron microscopy, transmission electron microscopy, high-resolution X-ray diffraction, room temperature micro-photoluminescence, and micro-Raman measurements. Surprisingly, the graphene with AlN buffer layer formed using less MEE cycles, thus resulting in lower AlN coverage, has a lower level of nitrogen plasma damage. The AlN buffer layer with lowest AlN coverage also provides the best result with respect to high-quality and vertically-aligned GaN nanocolumns. Recent progresses in the growth of GaN thin-film on graphene 1-6 increasingly justify the possibility for graphene to be a good alternative substrate over the available conventional substrates, for instance Si 7,8 , SiC 9 and sapphire 10. It is also reported that GaN thin-film is achievable on sapphire or amorphous substrates by employing either multi-layer or single-layer graphene as buffer layer 11-14. Such exploitations can be realized by taking advantage of the weak quasi-van der Waals binding 15-17 which can drastically relax the lattice matching condition to be satisfied by constituent materials. That being said, the lack of chemical reactivity of graphene and its extremely low surface energy 18 greatly disrupt the nucleation process of GaN, resulting in a low nucleation density 19 and difficulty in controlling the stacking sequence of the GaN growth 3. The latter issue, which often manifests in the form of stacking faults 3,5 or threading dislocations 1,4,17 , can possibly be suppressed by growing nanowire or nanocolumn structures 16,20-25. Nevertheless, because of the absence of dangling bonds in graphene, nanocolumns are often aligned in non-vertical directions 26-28 and/or have low density 27,29. Both problems are required to be addressed in order to demonstrate that the growth of III-N semiconductor nanostructures, particularly nanocolumns, utilizing graphene as the substrate can be further considered as an alternative platform in enabling the advancement of optoelectronic device performance and functionality, for instance light-emitting diodes 30. In this regard, the introduction of defects in graphene by means of plasma treatments could alleviate the issue of absence of dangling...

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“…However, a broad range of values for the surface energy of graphene has been reported. For instance, a direct measurement of the surface energy using a surface force apparatus 18 gave E ss = 115 ± 4 mJ/m 2 . If we use this value in Eq.…”

Section: Introductionmentioning

confidence: 99%

Liquid exfoliation of multilayer graphene in sheared solvents: A molecular dynamics investigation

Gravelle

Kamal

Botto

2020

The Journal of Chemical Physics

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Liquid-phase exfoliation, the use of a sheared liquid to delaminate graphite into few-layer graphene, is a promising technique for the large-scale production of graphene. But the micro and nanoscale fluid-structure processes controlling the exfoliation are not fully understood. Here we perform non-equilibrium molecular dynamics simulations of a defect-free graphite nanoplatelet suspended in a shear flow and measure the critical shear rateγ c needed for the exfoliation to occur. We compareγ c for different solvents including water and NMP, and nanoplatelets of different lengths. Using a theoretical model based on a balance between the work done by viscous shearing forces and the change in interfacial energies upon layer sliding, we are able to predict the critical shear ratesγ c measured in simulations. We find that an accurate prediction of the exfoliation of short graphite nanoplatelets is possible only if both hydrodynamic slip and the fluid forces on the graphene edges are considered, and if an accurate value of the solid-liquid surface energy is used. The commonly used"geometric-mean" approximation for the solid-liquid energy leads to grossly incorrect predictions. arXiv:1912.03179v1 [cond-mat.soft]

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Direct Measurement of the Surface Energy of Graphene

Cited by 103 publications

References 45 publications

Advances in Graphene‐Based Liquid Cell Electron Microscopy: Working Principles, Opportunities, and Challenges

Advances in Graphene‐Based Liquid Cell Electron Microscopy: Working Principles, Opportunities, and Challenges

The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene

Liquid exfoliation of multilayer graphene in sheared solvents: A molecular dynamics investigation

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