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Ultrasound exfoliation of inorganic analogues of graphene.

Stengl V, Henych J, Slušná M, Ecorchard P - Nanoscale Res Lett (2014)

Bottom Line: The monolayer slices could potentially be prepared with a high yield (up to 100%) in a few minutes.Atomic force microscopy (AFM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were employed to verify the quality of the exfoliation.Herein, this new method of exfoliation with ultrasound assistance for application to mono- and bilayered materials in hydrophobic and hydrophilic environments is presented.

View Article: PubMed Central - HTML - PubMed

Affiliation: Materials Chemistry Department, Institute of Inorganic Chemistry AS CR, v,v,i,, ŘeŽ 250 68, Czech Republic. stengl@iic.cas.cz.

ABSTRACT
High-intensity ultrasound exfoliation of a bulk-layered material is an attractive route for large-scale preparation of monolayers. The monolayer slices could potentially be prepared with a high yield (up to 100%) in a few minutes. Exfoliation of natural minerals (such as tungstenite and molybdenite) or bulk synthetic materials (including hexagonal boron nitride (h-BN), hexagonal boron carbon nitride (h-BCN), and graphitic carbon nitride (g-C3N4)) in liquids leads to the breakdown of the 3D graphitic structure into a 2D structure; the efficiency of this process is highly dependent upon the physical effects of the ultrasound. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were employed to verify the quality of the exfoliation. Herein, this new method of exfoliation with ultrasound assistance for application to mono- and bilayered materials in hydrophobic and hydrophilic environments is presented.

No MeSH data available.


AFM image and analysis of chemically exfoliated h-BN.
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Figure 8: AFM image and analysis of chemically exfoliated h-BN.

Mentions: The definite proof of the presence of exfoliated IAG sheets was provided by AFM, which can determine the height and therefore the number of layers. Figures 4 and 5 show the typical tapping-mode AFM images of MoS2 and WS2 exfoliated sheets using (a) dimethylformamide (DMF) and (b) the mixture of KMnO4 and KOH, which were deposited on a mica substrate. Cross-sectional analysis shows that the exfoliated MoS2 sheet had a thickness of approximately 0.7 nm and a lateral size of approximately 0.5 × 1.0 μm. Similarly, the exfoliated WS2 sheets possess a thickness of approximately 0.7 to 1 nm and a size of 80 to 100 nm. Thus, the conclusion from the observation of exfoliated WS2 and MoS2 is that single-layered sheets were achieved. This result is consistent with the aforementioned TEM observation. Figures 6 and 7 present AFM images of ultrasonically exfoliated h-BN and h-BCN. As seen in these figures, power ultrasound provided very uniformly delaminated materials. The analysis of the height profiles of both h-BN and h-BCN indicated that the thickness of the sheets is approximately 1 nm. This would note that the treated bulk-layered material provided mostly single (or double) sheets [48]. An important fact to emphasize is the height uniformity of the particles (clearly visible from the color scale) in the selected spots of the samples in the AFM analysis. Power ultrasound can therefore be suitable for larger scale production of homogeneous samples. The quality of the exfoliation by ultrasonic waves is evident in the comparison with chemically delaminated BN produced by the modified Hummers method [36]. As seen in the picture from the AFM microscope (see Figure 8), chemical delamination provided mostly 10-nm-thick particles of h-BN.


Ultrasound exfoliation of inorganic analogues of graphene.

Stengl V, Henych J, Slušná M, Ecorchard P - Nanoscale Res Lett (2014)

AFM image and analysis of chemically exfoliated h-BN.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4022084&req=5

Figure 8: AFM image and analysis of chemically exfoliated h-BN.
Mentions: The definite proof of the presence of exfoliated IAG sheets was provided by AFM, which can determine the height and therefore the number of layers. Figures 4 and 5 show the typical tapping-mode AFM images of MoS2 and WS2 exfoliated sheets using (a) dimethylformamide (DMF) and (b) the mixture of KMnO4 and KOH, which were deposited on a mica substrate. Cross-sectional analysis shows that the exfoliated MoS2 sheet had a thickness of approximately 0.7 nm and a lateral size of approximately 0.5 × 1.0 μm. Similarly, the exfoliated WS2 sheets possess a thickness of approximately 0.7 to 1 nm and a size of 80 to 100 nm. Thus, the conclusion from the observation of exfoliated WS2 and MoS2 is that single-layered sheets were achieved. This result is consistent with the aforementioned TEM observation. Figures 6 and 7 present AFM images of ultrasonically exfoliated h-BN and h-BCN. As seen in these figures, power ultrasound provided very uniformly delaminated materials. The analysis of the height profiles of both h-BN and h-BCN indicated that the thickness of the sheets is approximately 1 nm. This would note that the treated bulk-layered material provided mostly single (or double) sheets [48]. An important fact to emphasize is the height uniformity of the particles (clearly visible from the color scale) in the selected spots of the samples in the AFM analysis. Power ultrasound can therefore be suitable for larger scale production of homogeneous samples. The quality of the exfoliation by ultrasonic waves is evident in the comparison with chemically delaminated BN produced by the modified Hummers method [36]. As seen in the picture from the AFM microscope (see Figure 8), chemical delamination provided mostly 10-nm-thick particles of h-BN.

Bottom Line: The monolayer slices could potentially be prepared with a high yield (up to 100%) in a few minutes.Atomic force microscopy (AFM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were employed to verify the quality of the exfoliation.Herein, this new method of exfoliation with ultrasound assistance for application to mono- and bilayered materials in hydrophobic and hydrophilic environments is presented.

View Article: PubMed Central - HTML - PubMed

Affiliation: Materials Chemistry Department, Institute of Inorganic Chemistry AS CR, v,v,i,, ŘeŽ 250 68, Czech Republic. stengl@iic.cas.cz.

ABSTRACT
High-intensity ultrasound exfoliation of a bulk-layered material is an attractive route for large-scale preparation of monolayers. The monolayer slices could potentially be prepared with a high yield (up to 100%) in a few minutes. Exfoliation of natural minerals (such as tungstenite and molybdenite) or bulk synthetic materials (including hexagonal boron nitride (h-BN), hexagonal boron carbon nitride (h-BCN), and graphitic carbon nitride (g-C3N4)) in liquids leads to the breakdown of the 3D graphitic structure into a 2D structure; the efficiency of this process is highly dependent upon the physical effects of the ultrasound. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were employed to verify the quality of the exfoliation. Herein, this new method of exfoliation with ultrasound assistance for application to mono- and bilayered materials in hydrophobic and hydrophilic environments is presented.

No MeSH data available.