Nanoplatelets made from MoS2 and WS2

Bertram, Nils; Cordes, Jörn; Kim, Young Dok; Ganteför, Gerd; Gemming, Sibylle; Seifert, Gotthard

doi:10.1016/j.cplett.2005.10.046

Cited by 48 publications

(59 citation statements)

References 25 publications

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“…Therefore, the exact reaction mechanism that leads to the formation of the nanooctahedra remains still an open issue. Recently several papers were published concerning triangular monolayers of MoS 2 and WS 2, which presented both experimental and theoretical grounds for the relative stability of such structures (25)(26)(27)(28). Apparently, these structures are stabilized by the addition of excess S atoms in the form of S 2 pairs at the edges.…”

Section: Resultsmentioning

confidence: 99%

“…In some cases, pentagonal projections and triangular projections of MoS 2 were also detected in the soot, possibly representing a pentagonal bi-pyramid and a triangular prism, respectively, or a distorted version of them also constructed by triangular faces. Moreover, experiments and DFT calculations indicated that the WS 2 (MoS 2 ) triangular monolayers were metallic-like as a result of the sulfur pairs at the structure rims (25). The absence of the triangular faces in the soot produced by the laser ablation experiments may be attributed to the difficulty in detecting these minute monolayers even with advanced microscopes.…”

Section: Resultsmentioning

confidence: 99%

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Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures

Bar‐Sadan

Houben

Enyashin

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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The characterization of nanostructures down to the atomic scale is essential to understand some physical properties. Such a characterization is possible today using direct imaging methods such as aberration-corrected high-resolution transmission electron microscopy (HRTEM), when iteratively backed by advanced modeling produced by theoretical structure calculations and image calculations. Aberration-corrected HRTEM is therefore extremely useful for investigating low-dimensional structures, such as inorganic fullerene-like particles and inorganic nanotubes. The atomic arrangement in these nanostructures can lead to new insights into the growth mechanism or physical properties, where imminent commercial applications are unfolding. This article will focus on two structures that are symmetric and reproducible. The first structure that will be dealt with is the smallest stable symmetric closed-cage structure in the inorganic system, a MoS 2 nanooctahedron. It is investigated by means of aberration-corrected microscopy which allowed validating the suggested DFTB-MD model. It will be shown that structures diverging from the energetically most stable structures are present in the laser ablated soot and that the alignment of the different shells is parallel, unlike the bulk material where the alignment is antiparallel. These findings correspond well with the high-energy synthetic route and they provide more insight into the growth mechanism. The second structure studied is WS2 nanotubes, which have already been shown to have a unique structure with very desirable mechanical properties. The joint HRTEM study combined with modeling reveals new information regarding the chirality of the different shells and provides a better understanding of their growth mechanism.aberration-corrected high-resolution transmission electron microscopy ͉ inorganic closed-cage structures

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures

Bar‐Sadan

Houben

Enyashin

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…James et al [19] reported MoOC, Mo O O OS, and MoON cluster formation O in the gas phase. Mo and W disulfide nanoplatelets in the gas phase have been studied by Bertram et al [20]. Gemming et al [21] explored the small metal sulfide M x S y (M ϭ Mo, W; x ϭ 1, 2, 4; y ϭ 1-12) clusters using theoretical calculations and mass spectrometry.…”

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confidence: 99%

Closed-cage clusters in the gaseous and condensed phases derived from sonochemically synthesized MoS₂ nanoflakes

Singh

Pradeep

Bhattacharjee

et al. 2007

J. Am. Soc. Mass Spectrom.

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The Mo 13 clusters we previously reported were derived from MoS 2 flakes prepared from bulk MoS 2 , although the nature of the precursor species was not fully understood. The existence of the clusters in the condensed phase was a question. Here we report the preparation of MoS 2 nanoflakes from elemental precursors using the sonochemical method and study the gas-phase clusters derived from them using mass spectrometry. Ultraviolet-visible (UV-vis) spectrum of the precursor is comparable to nano MoS 2 derived from bulk MoS 2 . High-resolution transmission electron microscopy (HRTEM) revealed the formation of nanoflakes of MoS 2 with 10-to 30-nm length and 3-to 5-nm thickness. Laser desorption ionization mass spectrometry (LDI-MS) confirmed the formation of Mo 13 clusters from this nanomaterial. Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) points to the existence of Mo 13 clusters in the condensed phase. The clusters appear to be stable because they do not fragment in the mass spectrometer even at the highest laser intensity. Computational analysis based on generalized Wannier orbitals is used to understand bonding and stability of the clusters. These clusters are highly stable with a rich variety in terms of centricity and multiplicity of MoOMo There are several synthetic approaches such as gas-phase deposition [5,6], laser ablation [7,8], electron irradiation [9], and high-temperature chemical routes [10,11] for the synthesis of clusters. Nano forms of these materials have their own advantages over the corresponding bulk materials. Electrochemical deposition [12] and sonochemical routes [13,14] are some other methods adapted for the synthesis of nanostructured materials. Electrochemical methods result in the formation of nanomaterials as a film, whereas sonochemical methods produce free-standing nanoflakes of metal chalcogenides with controlled size.

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“…In the gas phase, the most stable platelet is W 15 S 42 and the smallest observed platelet is W 10 S 30 . [23][24][25] The octahedral shape of the nested inorganic fullerenes indicates that two-dimensional triangular structures are preferred by MoS 2 and WS 2 . No "single-wall" real fullerenes have been found until today.…”

Section: Introductionmentioning

confidence: 99%

“…It is already known that the particles in the first maximum are one-dimensional chains and two-dimensional platelets. [23][24][25] Here, we focus on the structure determination of the larger clusters in the second maximum. These clusters are studied with anion photoelectron spectroscopy, scanning transmission electron microscopy, and scanning tunneling microscopy.…”

Section: Introductionmentioning

confidence: 99%

The quest for inorganic fullerenes

Pietsch

Dollinger

Strobel

et al. 2015

Journal of Applied Physics

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Experimental results of the search for inorganic fullerenes are presented. MonSm− and WnSm− clusters are generated with a pulsed arc cluster ion source equipped with an annealing stage. This is known to enhance fullerene formation in the case of carbon. Analogous to carbon, the mass spectra of the metal chalcogenide clusters produced in this way exhibit a bimodal structure. The species in the first maximum at low mass are known to be platelets. Here, the structure of the species in the second maximum is studied by anion photoelectron spectroscopy, scanning transmission electron microscopy, and scanning tunneling microcopy. All experimental results indicate a two-dimensional structure of these species and disagree with a three-dimensional fullerene-like geometry. A possible explanation for this preference of two-dimensional structures is the ability of a two-element material to saturate the dangling bonds at the edges of a platelet by excess atoms of one element. A platelet consisting of a single element only cannot do this. Accordingly, graphite and boron might be the only materials forming nano-spheres because they are the only single element materials assuming two-dimensional structures.

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Nanoplatelets made from MoS2 and WS2

Cited by 48 publications

References 25 publications

Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures

Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures

Closed-cage clusters in the gaseous and condensed phases derived from sonochemically synthesized MoS₂ nanoflakes

The quest for inorganic fullerenes

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Nanoplatelets made from MoS2 and WS2

Cited by 48 publications

References 25 publications

Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures

Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures

Closed-cage clusters in the gaseous and condensed phases derived from sonochemically synthesized MoS2 nanoflakes

The quest for inorganic fullerenes

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Closed-cage clusters in the gaseous and condensed phases derived from sonochemically synthesized MoS₂ nanoflakes