Tungsten disulfide
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 Left: WS2 film on sapphire. Right: dark exfoliated WS2 film floating on water.
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| Names | |
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IUPAC names
Tungsten disulfide
Bis(sulfanylidene)tungsten |
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Systematic IUPAC name
Dithioxotungsten
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| Other names
Tungsten(IV) sulfide
Tungstenite |
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| Identifiers | |
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3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.032.027 |
| EC Number | 235-243-3 |
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PubChem CID
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| Properties | |
| WS2 | |
| Molar mass | 247.98 g/mol |
| Appearance | blue-gray powder |
| Density | 7.5 g/cm3, solid |
| Melting point | 1,250 °C (2,280 °F; 1,520 K) decomposes |
| slightly soluble | |
| Band gap | ~1 eV (indirect, bulk) ~1.8 eV (direct, monolayer) |
| +5850·10−6 cm3/mol | |
| Structure | |
| Molybdenite | |
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Trigonal prismatic (WIV) Pyramidal (S2−) |
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| Related compounds | |
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Other anions
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Tungsten(IV) oxide, Tungsten diselenide |
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Other cations
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Molybdenum disulfide |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
Tungsten disulfide is the chemical compound with the formula WS2. It occurs naturally as the rare mineral tungstenite. This material is a component of certain catalysts used for hydrodesulfurization and hydrodenitrification.
WS2 adopts a layered structure related to MoS2, with W atoms situated in trigonal prismatic coordination sphere. Owing to this layered structure, WS2 forms inorganic nanotubes, which were discovered on an example of WS2 in 1992.
Bulk WS2 forms dark gray hexagonal crystals with a layered structure. Like the closely related MoS2, it exhibits properties of a dry lubricant. It is chemically fairly inert but is attacked by a mixture of nitric and hydrofluoric acids. When heated in oxygen-containing atmosphere, WS2 converts to tungsten trioxide. When heated in absence of oxygen, WS2 does not melt but decomposes to tungsten and sulfur, but only at 1250 °C.
The material undergoes exfoliation by treatment with various reagents such as chlorosulfonic acid.
WS2 is produced by a number of methods. Many of these methods involve treating oxides with sources of sulfide or hydrosulfide, supplied as hydrogen sulfide or generated in situ. Other routes entail thermolysis of tungsten(VI) sulfides (e.g., (R4N)2WS4) or the equivalent (e.g., WS3).
Freestanding WS2 films can produced as follows. WS2 is deposited on a hydrophilic substrate, such as sapphire, and then coated with a polymer, such as polystyrene. After dipping the sample in water for a few minutes, the hydrophobic WS2 film spontaneously peels off.
WS2 is used, in conjunction with other materials, as catalyst for hydrotreating of crude oil.
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