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

CAS Number

* 12058-18-3 Y

3D model (JSmol)

* Interactive image

ChemSpider |

* 74797

EC Number |

* 235-027-9

PubChem CID

* 82894

InChI

* InChI=1S/Mo.2Se

Key: MHWZQNGIEIYAQJ-UHFFFAOYSA-N

SMILES

* [Se]=[Mo]=[Se]

Properties

Chemical formula

| MoSe2
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]

Refractive index (nD)

| 1.4--3.4 (ultraviolet)
3.4--5.1 (visible)
4.2--4.9 (near infrared)[5]
Structure

Crystal structure

| hP6, space group P63/mmc, No 194[6]

Lattice constant

a = 0.3283 nm, c = 1.2918 nm

Coordination geometry

| 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).

Infobox references

Tracking categories (test):

* SizeSet

Molybdenum diselenide (MoSe2) is an inorganic compound of molybdenum and selenium. Its structure is similar to that of MoS2.[7] Compounds of this category are known as transition metal dichalcogenides, abbreviated TMDCs. These compounds, as the name suggests, are made up of a transition metals and elements of group 16 on the periodic table of the elements. Compared to MoS2, MoSe2 exhibits higher electrical conductivity.[8]

## Contents

* 1 Structure
* 2 Synthesis
* 3 Properties
* 4 Natural occurrence
* 5 References

## Structure

Like many TMDCs, MoSe2 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.[9]

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.[10]

## Synthesis

Synthesis of MoSe2 involves direct reaction of molybdenum and selenium in a sealed tube at high temperature. Chemical vapor transport with a halogen (usually bromine or iodine) is used to purify the compound at very low pressure (less than 10-6 torr) and very high temperature (600–700 °C). It has to be heated very gradually to prevent explosion due to its strong exothermic reaction. Stoichiometric layers crystallize in a hexagonal structure as the sample cools.[10] Excess selenium can be removed by sublimation under vacuum.[11] The synthesis reaction of MoSe2 is:

Mo + 2 Se → MoSe2

Single-crystal-thick layers of MoSe2 are produced by scotch tape exfoliation from bulk crystals,[12] by chemical vapor deposition (CVD) [13] or molecular-beam epitaxy (MBE).[14]

## Properties

The electron mobility of 2D-MoSe2 is significantly higher than that of 2D-MoS2. 2D MoSe2 adopts structures reminiscent of graphene, although the latter's electron mobility is thousands of times greater still.

In contrast to graphene, monolayer MoSe2 has a direct band gap, suggesting applications in transistors and photodetectors. However, the band gap of multilayer MoSe2 is indirect. [13]

In-plane (nxy) and out-of-plane (nz) refractive index spectra of molybdenum diselenide with respective extinction coefficient spectra (kxy, kz).[5]

Molybdenum diselenide exhibits anisotropy of the refractive index. The in-plane refractive index has exceptionally high values, extending 4 for wavelengths above 430 nm and reaching a maximum value of 5.117 for 825 nm, while the out-of-plane refractive index is near 3 in the visible and the infrared range of the spectrum. MoSe2 highly absorb the visible light but is transparent for the infrared.[5]

## Natural occurrence

Molybdenum(IV) selenide occurs in the nature as the extremely rare mineral drysdallite.[15]

## References

1. ↑ Iberi, Vighter; Liang, Liangbo; Ievlev, Anton V.; Stanford, Michael G.; Lin, Ming-Wei; Li, Xufan; Mahjouri-Samani, Masoud; Jesse, Stephen et al. (2016). "Nanoforging Single Layer MoSe2 Through Defect Engineering with Focused Helium Ion Beams". Scientific Reports 6. doi:10.1038/srep30481. PMID 27480346. Bibcode: 2016NatSR...630481I.
2. ↑ 2.0 2.1 2.2 Haynes, William M., ed (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.76. ISBN 1439855110.
3. ↑ Yun, Won Seok; Han, S. W.; Hong, Soon Cheol; Kim, In Gee; Lee, J. D. (2012). "Thickness and strain effects on electronic structures of transition metal dichalcogenides: 2H-MX2 semiconductors (M = Mo, W; X = S, Se, Te)". Physical Review B 85 (3). doi:10.1103/PhysRevB.85.033305. Bibcode: 2012PhRvB..85c3305Y.
4. ↑ Kioseoglou, G.; Hanbicki, A. T.; Currie, M.; Friedman, A. L.; Jonker, B. T. (2016). "Optical polarization and intervalley scattering in single layers of MoS2 and MoSe2". Scientific Reports 6. doi:10.1038/srep25041. PMID 27112195. Bibcode: 2016NatSR...625041K.
5. ↑ 5.0 5.1 5.2 Pruszyńska-Karbownik, Emilia; Fąs, Tomasz; Brańko, Katarzyna; Yavorskiy, Dmitriy; Stonio, Bartłomiej; Bożek, Rafał; Karbownik, Piotr; Wróbel, Jerzy et al. (2026). "Optical Bound States in the Continuum in Subwavelength Gratings Made of an Epitaxial van der Waals Material". ACS Nano 20 (9): 7426-7437. doi:10.1021/acsnano.5c12870. https://doi.org/10.1021/acsnano.5c12870. Retrieved 15 April 2026.
6. ↑ Agarwal, M. K.; Patel, P. D.; Joshi, R. M. (1986). "Growth conditions and structural characterization of MoSexTe2−x (0 ⩽ x ⩽ 2) single crystals". Journal of Materials Science Letters 5: 66–68. doi:10.1007/BF01671439.
7. ↑ Greenwood, N. N.; Earnshaw, A. (11 November 1997). Chemistry of the Elements. Elsevier. pp. 1017–1018. ISBN 978-0-08-050109-3. https://books.google.com/books?id=EvTI-ouH3SsC.
8. ↑ Eftekhari, Ali (2017). "Molybdenum Diselenide (MoSe2) for Energy Storage, Catalysis, and Optoelectronics". Applied Materials Today 8: 1–16. doi:10.1016/j.apmt.2017.01.006.MoSe2)+for+Energy+Storage,+Catalysis,+and+Optoelectronics&rft.jtitle=Applied+Materials+Today&rft.aulast=Eftekhari&rft.aufirst=Ali&rft.au=Eftekhari, Ali&rft.date=2017&rft.volume=8&rft.pages=1–16&rft_id=info:doi/10.1016/j.apmt.2017.01.006&rfr_id=info:sid/en.wikibooks.org:Chemistry:Molybdenum_diselenide">
9. ↑ Wang, Qing Hua; Kalantar-Zadeh, Kourosh; Kis, Andras; Coleman, Jonathan N.; Strano, Michael S. (2012). "Electronics and optoelectronics of two-dimensional transition metal dichalcogenides". Nature Nanotechnology 7 (11): 699–712. doi:10.1038/nnano.2012.193. PMID 23132225. Bibcode: 2012NatNa...7..699W. http://infoscience.epfl.ch/record/182177.
10. ↑ 10.0 10.1 Parilla, P.; Dillon, A.; Parkinson, B.; Jones, K.; Alleman, J.; Riker, G.; Ginley, D.; Heben, M; Formation of Nanooctahedra in Molybdenum Disulfide and Molybdenum Diselenide Using Pulsed Vapor Transport doi:10.1021/jp036202
11. ↑ Al-hilli, A.; Evans, L. The Preparation and Properties of Transition Metal Dichalcogenide Single Crystals. Journal of Crystal Growth. 1972. 15, 93–101. doi:10.1016/0022-0248(72)90129-7
12. ↑ Phalswal, Priyanka; Khanna, Pawan K.; Rubahn, Horst-Günter; Mishra, Yogendra Kumar (2022). "Nanostructured molybdenum dichalcogenides: a review". Materials Advances 3: 5672-5697. doi:10.1039/D2MA00150K. https://pubs.rsc.org/en/content/articlehtml/2022/ma/d2ma00150k. Retrieved 10 March 2026.
13. ↑ 13.0 13.1 "Scalable CVD process for making 2-D molybdenum diselenide". Rdmag.com. 2014-04-04. http://www.rdmag.com/news/2014/04/scalable-cvd-process-making-2-d-molybdenum-diselenide.
14. ↑ Pacuski, Wojciech; Grzeszczyk, Magdalena; Nogajewski, Karol; Bogucki, Aleksander; Bożek, Rafał; Taniguchi, Takashi; Watanabe, Kenji; Kret, Slawomir et al. (2020). "Narrow Excitonic Lines and Large-Scale Homogeneity of Transition-Metal Dichalcogenide Monolayers Grown by Molecular Beam Epitaxy on Hexagonal Boron Nitride". Nano Letters 20 (5): 3058–3066. doi:10.1021/acs.nanolett.9b04998. https://pubs.acs.org/doi/10.1021/acs.nanolett.9b04998. Retrieved 10 March 2026.
15. ↑ "Home". http://www.mindat.org/.

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Molybdenum compounds

Mo(0)|

* Mo(CO)6

Mo(II)|

* MoBr2
* MoCl2
* MoSi2

Mo(III)|

* MoBr3
* MoCl3
* MoI3
* Mo2O3

Mo(IV)|

* MoCl4
* MoF4
* MoO2
* MoS2

Mo(V)|

* MoCl5
* MoF5
* Mo2O5

Mo(VI)|

* MoF6
* MoO3
* MoS3

* v
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Selenides

| H2Se
H2Se2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | He

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Li2Se | Be |  |  |  |  |  |  |  |  |  |  | B | CSe2
OCSe | (NH4)2Se | O | F | Ne
Na2Se | MgSe |  |  |  |  |  |  |  |  |  |  | Al2Se3 | Si | PxSey | S | Cl | Ar
K2Se | CaSe | Sc2Se3 | TiSe2 | V | CrSe
Cr2Se3 | MnSe
MnSe2 | FeSe | CoSe | NiSe | CuSe | ZnSe | GaSe
Ga2Se3 | GeSe | As2Se3
As4Se3 | Se | Br | Kr
Rb2Se | SrSe | Y2Se3 | Zr | NbSe2
NbSe3 | MoSe2 | Tc | Ru | Rh | Pd | Ag2Se | CdSe | In2Se3 | SnSe
SnSe2 | Sb2Se3 | Te | I | Xe
Cs2Se | BaSe | *  | Hf | Ta | WSe2
WSe3 | ReSe2 | Os | Ir | Pt | Au | HgSe | Tl2Se | PbSe | Bi2Se3 | Po | At | Rn
Fr | Ra | **  | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | CnSe | Nh | Fl | Mc | Lv | Ts | Og |  |  |  |  |  |  |  |
|  | ↓ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| * | La2Se3 | Ce2Se3 | Pr2Se3 | Nd2Se3 | Pm | Sm2Se3 | Eu2Se3 | Gd | Tb | Dy | Ho | Er2Se3 | Tm2Se3 | Yb | Lu |
| ** | Ac | ThSe2 | Pa | USe2 | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |

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