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The MoS 2 Nanotubes with Defect-Controlled Electric Properties

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ABSTRACT

We describe a two-step synthesis of pure multiwall MoS2 nanotubes with a high degree of homogeneity in size. The Mo6S4I6 nanowires grown directly from elements under temperature gradient conditions in hedgehog-like assemblies were used as precursor material. Transformation in argon-H2S/H2 mixture leads to the MoS2 nanotubes still grouped in hedgehog-like morphology. The described method enables a large-scale production of MoS2 nanotubes and their size control. X-ray diffraction, optical absorption and Raman spectroscopy, scanning electron microscopy with wave dispersive analysis, and transmission electron microscopy were used to characterize the starting Mo6S4I6 nanowires and the MoS2 nanotubes. The unit cell parameters of the Mo6S4I6 phase are proposed. Blue shift in optical absorbance and metallic behavior of MoS2 nanotubes in two-probe measurement are explained by a high defect concentration.

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The MoS2 nanotubes: a A typical TEM image of a bunch of nanotubes grown from sacrificed Mo6S4I6 nanowires keeping their outer geometry; and b self-organization in hedgehock-like groups revealed by SEM; c HRTEM image of a nanotube's wall with resolved MoS2 molecular layers, stacking faults and atomically rough surface; d TEM image of a single nanotube cap of a nanotube with inner cylinders terminated by curved layers of outer cylinders.
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Figure 3: The MoS2 nanotubes: a A typical TEM image of a bunch of nanotubes grown from sacrificed Mo6S4I6 nanowires keeping their outer geometry; and b self-organization in hedgehock-like groups revealed by SEM; c HRTEM image of a nanotube's wall with resolved MoS2 molecular layers, stacking faults and atomically rough surface; d TEM image of a single nanotube cap of a nanotube with inner cylinders terminated by curved layers of outer cylinders.

Mentions: The MoS2 multiwall nanotubes gained by the sulfurization after complete iodine removal keep the shape of the precursor Mo6S4I6 nanowires (Figure 3a). The nanotubes are still organized in hedgehog-like groups (Figure 3b). The tube walls with a typical thickness below 10 nm are strongly defected (Figure 3c). The lattice defects condensate forming faceting of the dome closure or disorder areas near stacking faults of MoS2 layers. Some inner cylinders can be terminated by curved players of outer cylinders (Figure 3d) revealing a dominant tendency of self-termination of surface molecular layers, while the inner ones did not gain sufficient energy for a closure.


The MoS 2 Nanotubes with Defect-Controlled Electric Properties
The MoS2 nanotubes: a A typical TEM image of a bunch of nanotubes grown from sacrificed Mo6S4I6 nanowires keeping their outer geometry; and b self-organization in hedgehock-like groups revealed by SEM; c HRTEM image of a nanotube's wall with resolved MoS2 molecular layers, stacking faults and atomically rough surface; d TEM image of a single nanotube cap of a nanotube with inner cylinders terminated by curved layers of outer cylinders.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211322&req=5

Figure 3: The MoS2 nanotubes: a A typical TEM image of a bunch of nanotubes grown from sacrificed Mo6S4I6 nanowires keeping their outer geometry; and b self-organization in hedgehock-like groups revealed by SEM; c HRTEM image of a nanotube's wall with resolved MoS2 molecular layers, stacking faults and atomically rough surface; d TEM image of a single nanotube cap of a nanotube with inner cylinders terminated by curved layers of outer cylinders.
Mentions: The MoS2 multiwall nanotubes gained by the sulfurization after complete iodine removal keep the shape of the precursor Mo6S4I6 nanowires (Figure 3a). The nanotubes are still organized in hedgehog-like groups (Figure 3b). The tube walls with a typical thickness below 10 nm are strongly defected (Figure 3c). The lattice defects condensate forming faceting of the dome closure or disorder areas near stacking faults of MoS2 layers. Some inner cylinders can be terminated by curved players of outer cylinders (Figure 3d) revealing a dominant tendency of self-termination of surface molecular layers, while the inner ones did not gain sufficient energy for a closure.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

We describe a two-step synthesis of pure multiwall MoS2 nanotubes with a high degree of homogeneity in size. The Mo6S4I6 nanowires grown directly from elements under temperature gradient conditions in hedgehog-like assemblies were used as precursor material. Transformation in argon-H2S/H2 mixture leads to the MoS2 nanotubes still grouped in hedgehog-like morphology. The described method enables a large-scale production of MoS2 nanotubes and their size control. X-ray diffraction, optical absorption and Raman spectroscopy, scanning electron microscopy with wave dispersive analysis, and transmission electron microscopy were used to characterize the starting Mo6S4I6 nanowires and the MoS2 nanotubes. The unit cell parameters of the Mo6S4I6 phase are proposed. Blue shift in optical absorbance and metallic behavior of MoS2 nanotubes in two-probe measurement are explained by a high defect concentration.

No MeSH data available.


Related in: MedlinePlus