Molybdenum diselenide

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Molybdenum diselenide
Molybdenum diselenide

Top-view atomic images of MoSe2 before and after (right) ion irradiation[1]
Names
IUPAC name
bis(selanylidene)molybdenum
Other names
molybdenum diselenide, molybdenumdiselenide, molybdenum selenide, diselanylidenemolybdenum, molybdenum(IV) selenide
Identifiers
3D model (
JSmol
)
ECHA InfoCard
 100.031.831 Edit this at Wikidata
  • [Se]=[Mo]=[Se]
Properties
MoSe
2
Molar mass 253.86 g/mol[2]
Appearance crystalline solid
Density 6.90 g/cm3[2]
Melting point >1200 °C[2]
Band gap ~0.85 eV (indirect, bulk)
~1.5 eV (direct, monolayer)[3][4]
Structure
hP6, space group P6
3/mmc, No 194[5]
a = 0.3283 nm, c = 1.2918 nm
Trigonal prismatic
(MoIV)
Pyramidal (Se2−)
Related compounds
Other anions
 Molybdenum dioxide
Molybdenum disulfide
Molybdenum ditelluride
Tantalum diselenide
Other cations
 Tungsten diselenide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Molybdenum diselenide (MoSe
2) is an

periodic table of the elements. Compared to MoS
2, MoSe
2 exhibits higher electrical conductivity.[7]

Structure

Like many TMDCs, MoSe
2 is a layered material with strong in-plane bonding and weak out-of-plane interactions. These interactions lead to exfoliation into two-dimensional layers of single unit cell thickness.[8]

The most common form of these TMDCs have trilayers of molybdenum sandwiched between selenium ions causing a trigonal prismatic metal bonding coordination, but it is octahedral when the compound is exfoliated. The metal ion in these compounds is surrounded by six Se2−
 ions. The coordination geometry of the Mo is sometimes found as octahedral and trigonal prismatic.[9]

Synthesis

Synthesis of MoSe
2 involves direct reaction of molybdenum and selenium in a sealed tube at high temperature.

Stoichiometric layers crystallize in a hexagonal structure as the sample cools.[9] Excess selenium can be removed by sublimation under vacuum.[10]
The synthesis reaction of MoSe
2 is:

Mo + 2 Se → MoSe
2

2D-MoSe
2

Single-crystal-thick layers of MoSe
2 are produced by scotch tape exfoliation from bulk crystals or by chemical vapor deposition (CVD).[11][12]

The electron mobility of 2D-MoSe
2 is significantly higher than that of 2D-MoS
2. 2D MoSe
2 adopts structures reminiscent of graphene, although the latter's electron mobility is thousands of times greater still. In contrast to graphene, 2D-MoSe
2 has a direct band gap, suggesting applications in transistors and photodetectors.[11]

Natural occurrence

Molybdenum(IV) selenide occurs in the nature as the extremely rare mineral drysdallite.[13]

References

Wikimedia Commons has media related to Molybdenum diselenide.
  1. PMID 27480346
    .
  2. ^
    ISBN 1-4398-5511-0
    .
  3. doi:10.1103/PhysRevB.85.033305
    .
  4. PMID 27112195
    .
  5. S2CID 96858586
    .
  6. ISBN 978-0-08-050109-3
    .
  7. doi:10.1016/j.apmt.2017.01.006
    .
  8. S2CID 6261931
    .
  9. ^
    doi:10.1021/jp036202
  10. doi:10.1016/0022-0248(72)90129-7
  11. ^ a b "Scalable CVD process for making 2-D molybdenum diselenide". Rdmag.com. 2014-04-04. Retrieved 2014-04-09.
  12. PMID 24712299
    .
  13. ^ "Home". mindat.org.
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