Breakdown in the Wetting Transparency of Graphene

Shih, Chih‐Jen; Wang, Qing Hua; Lin, Shangchao; Park, Kyoo Chul; Jin, Zhong; Strano, Michael S.; Blankschtein, Daniel

doi:10.1103/physrevlett.109.176101

Cited by 330 publications

(357 citation statements)

References 39 publications

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“…The interface markers of the water droplet are obtained by applying the method that Rishi Raj used [21]. The result shows that the contact angle of water droplets on graphite is about 85.9°, which is in good agreement with experimental or other simulation data (80°−90°) [21][22][23][24][25]. Adamson et al [25] showed a contact angle of 86° by experimental In our simulation, the interatomic interaction is described by COMPASS force field.…”

Section: Model and Methodssupporting

confidence: 81%

Molecular Dynamics Study on the Effect of Surface Hydroxyl Groups on Three-Phase Wettability in Oil-Water-Graphite Systems

2017

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Abstract:In this paper, a hydroxylated graphite surface is generated as a hydrophilic oleophobic material for the application of oil-water separation, and the effects of hydroxyl density on the three-phase wettability are studied in oil-water-graphite systems. We analyze the adsorption of water molecules on the hydroxylated surfaces and obtain the relationship between water-oil-solid interfacial properties and the hydroxyl density, which results from the synthetic effects of the orientation of molecules and hydrogen bonds. With the increase of hydroxyl density, the water-solid contact angle first decreases rapidly, and then remains constant. The density of the hydrogen bond formed between hydroxyls and water molecules in the adsorption layer can explain the regularity of the three-phase wettability. The orientation of the water molecules in the adsorption layer shows insignificant variation, owing to the hydrogen bond network formed between the water molecules; thus, little change is observed in the hydrogen bond density in the adsorption layer.

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Section: Model and Methodssupporting

confidence: 81%

Molecular Dynamics Study on the Effect of Surface Hydroxyl Groups on Three-Phase Wettability in Oil-Water-Graphite Systems

2017

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“…Yet, the relatively few studies available are not in agreement, especially on the effect of the substrate. 29,60,61 To the best of our knowledge, the intrinsic wettability of suspended graphene has only been predicted theoretically by molecular dynamics, 62 and has not been measured, due to experimental challenges. Our studies suggest that Cu-supported graphene exhibits stronger wettability compared with a free-standing graphene sheet.…”

Section: Wetting and Electrochemistry Of Supported And Suspended Grapmentioning

confidence: 99%

“…This is in line with theoretical studies showing that the contact angle of water on suspended graphene is higher than on Cu-supported graphene. 29,[62][63][64] To further investigate the wettability of the suspended graphene membrane, approach and retract experiments were carried out in which the meniscus of an SECCM pipet was pushed further against the graphene with the precise control of the z-piezo, while iDC against z-piezo displacement was recorded, and the reverse (pull-off) of the meniscus was also measured. An example of these approach and retract curves (with ion conductance current iDC normalized to the initial value of the approach iIni, iDC/iIni) is presented in Figure 7 (which is typical of 3 different experiments).…”

Section: Wetting and Electrochemistry Of Supported And Suspended Grapmentioning

confidence: 99%

Versatile Polymer-Free Graphene Transfer Method and Applications

Zhang

Güell

Kirkman

et al. 2016

ACS Appl. Mater. Interfaces

106

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A new method for transferring chemical vapor deposition (CVD)-grown monolayer graphene, to a variety of substrates is described. The method makes use of an organic/aqueous biphasic configuration, avoiding the use of any polymeric materials that can cause severe contamination problems. The graphene-coated copper foil sample (on which graphene was grown) sits at the interface between hexane and an aqueous etching solution of ammonium persulfate to remove the copper. With the aid of an Si/SiO2 substrate, the graphene layer is then transferred to a second hexane/water interface, to remove etching products. From this new location, CVD graphene is readily transferred to arbitrary substrates, including three dimensional architectures as represented by atomic force microscopy (AFM) tips and transmission electron microscopy (TEM) grids. Graphene produces a conformal layer on AFM tips, to the very end, allowing the easy production of tips for conductive AFM imaging. Graphene transferred to copper TEM grids provides large area, highly electrontransparent substrates for TEM imaging. These substrates can also be used as working electrodes for electrochemistry and high resolution wetting studies. By using scanning electrochemical cell microscopy, it is possible to make electrochemical and wetting measurements at either a free-standing graphene film or a copper-supported graphene area, and readily determine any differences in behavior.3

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“…Calculations of the van der Waals and short range repulsive forces suggest that a graphene layer would alter the wetting properties on superhydrophilic and superhydrophobic substrates. 10 Hence, wetting transparency of graphene will break down on such superhydrophilic or superhydrophobic substrates. Contact angle measurements by Raj et al, 11 on the other hand, demonstrated that contact angles are independent of the number of graphene layers on a glass or on a silicon oxide substrate.…”

mentioning

confidence: 99%

“…adsorbed water molecule, one finds %10 22 molecules on the surface and %2. 10 18 molecules on the edges. Hence, the edge effects are negligible since they are 4 orders of magnitude smaller.…”

mentioning

confidence: 99%

Wetting of water on graphene nanopowders of different thicknesses

Bera¹,

Shahidzadeh²,

Mishra

et al. 2018

Applied Physics Letters

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We study the wetting of graphene nanopowders by measuring the water adsorption in nanopowder flakes of different flake thicknesses. Chemical analysis shows that the graphene flakes, especially the thin ones, might exist in the partially oxidized state. We observe that the thinnest graphene nanopowder flakes do not adsorb water at all, independent of the relative humidity. Thicker flakes, on the other hand, do adsorb an increasing amount of water with increasing humidity. This allows us to assess their wetting behavior which is actually the result of the competition between the adhesive interactions of water and graphene and the cohesive interactions of water. Explicit calculation of these contributions from the van der Waals interactions confirms that the adhesive interactions between very thin flakes of graphene oxide and water are extremely weak, which makes the flakes superhydrophobic. “Liquid marble” tests with graphene nanopowder flakes confirm the superhydrophobicity. This shows that the origin of the much debated “wetting transparency” of graphene is due to the fact that a single graphene or graphene oxide layer does not contribute significantly to the adhesion between a wetting phase and the substrate.

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Breakdown in the Wetting Transparency of Graphene

Cited by 330 publications

References 39 publications

Molecular Dynamics Study on the Effect of Surface Hydroxyl Groups on Three-Phase Wettability in Oil-Water-Graphite Systems

Molecular Dynamics Study on the Effect of Surface Hydroxyl Groups on Three-Phase Wettability in Oil-Water-Graphite Systems

Versatile Polymer-Free Graphene Transfer Method and Applications

Wetting of water on graphene nanopowders of different thicknesses

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