Molybdenum dioxide

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Molybdenum dioxide
Names
IUPAC name
Molybdenum(IV) oxide
Other names
Molybdenum dioxide
Tugarinovite
Identifiers
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PubChem CID
Properties
MoO2
Molar mass 127.94 g/mol
Appearancebrownish-violet solid
Density 6.47 g/cm3
Melting point 1,100 °C (2,010 °F; 1,370 K) decomposes
insoluble
Solubility insoluble in alkalies, HCl, HF
slightly soluble in hot H2SO4
+41.0·10−6 cm3/mol
Structure
Distorted rutile (monoclinic)
Octahedral (MoIV); trigonal (O−II)
Hazards
Flash point Non-flammable
Related compounds
Other anions
Molybdenum disulfide
Other cations
Chromium(IV) oxide
Tungsten(IV) oxide
"Molybdenum blue"
Molybdenum trioxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Molybdenum dioxide is the chemical compound with the formula MoO2. It is a violet-colored solid and is a metallic conductor. The mineralogical form of this compound is called tugarinovite, and is only very rarely found. The discovery and early studies of molybdenum dioxide date back to the late 18th and early 19th centuries. One of the notable figures in the history of molybdenum dioxide is the Hungarian chemist Jakob Joseph Winterl (1732–1809). Winterl, who was a professor of chemistry and botany at the University of Budapest, made significant contributions to the understanding of molybdenum compounds. In 1787, he proposed that copper was a compound of nickel, molybdenum, silica, and a volatile substance, showcasing his interest in molybdenum chemistry. [1]

Contents

Structure

Molybdenum dioxide (MoO2) exists in various crystalline forms, with the most common being the monoclinic (α-MoO2) and hexagonal structures. [2] It crystallizes in a monoclinic cell, and has a distorted rutile, (TiO2) crystal structure. In TiO2 the oxide anions are close packed and titanium atoms occupy half of the octahedral interstices (holes). In MoO2 the octahedra are distorted, the Mo atoms are off-centre, leading to alternating short and long Mo – Mo distances and Mo-Mo bonding. The short Mo – Mo distance is 251 pm which is less than the Mo – Mo distance in the metal, 272.5 pm. The bond length is shorter than would be expected for a single bond. The bonding is complex and involves a delocalisation of some of the Mo electrons in a conductance band accounting for the metallic conductivity. [3]

Preparation

One common approach for synthesizing molybdenum dioxide (MoO2) is through the thermal decomposition of molybdenum-containing precursor compounds. For example, ammonium molybdate tetrahydrate ((NH4)6Mo7O24·4H2O) can be used as a precursor and thermally decomposed on an activated carbon support to form crystalline MoO2.[ citation needed ] The decomposition typically occurs at temperatures in the range of 450–550 °C.[ citation needed ] The thermal behavior and decomposition mechanism of bis(alkylimido)-dichloromolybdenum(VI) adducts with neutral N,N'-chelating ligands has also been studied as precursors for MoO2. [4] It was found that the decomposition follows a general pathway, proceeding first by dissociation of the chelating ligand, then dimerization, intramolecular hydrogen transfer, and ultimately decomposition into molybdenum nitride or carbide species. [4] Understanding the thermal decomposition of Mo precursors is important for designing vapor-phase deposition processes for MoO2 thin films. [4]

MoO2 can also be prepared :

2 MoO3 + Mo → 3 MoO2

Single crystals are obtained by chemical transport using iodine. Iodine reversibly converts MoO2 into the volatile species MoO2I2. [6]

Uses

Electronic Applications

Molybdenum dioxide has shown promise in electronic applications due to its high work function and unique properties. In a study on symmetrical junction non-aligned double gate n-channel field effect transistors (NADGNFETs), researchers investigated the effects of metal work function and dielectric constant on device performance. [7] They found that using molybdenum, with a work function of 4.75 eV, as the gate metal significantly affected analog figures of merit such as ON current, ON/OFF current ratio, threshold voltage, and intrinsic gain.

Another study focused on the reliable synthesis of high work-function molybdenum dioxide via atomic layer deposition for next-generation electrode applications. [8] This highlights the potential of MoO2 in advanced electronic devices.

Energy Storage

Molybdenum dioxide has been explored as a component in energy storage systems, particularly in lithium-sulfur (Li-S) batteries. One study prepared one-dimensional molybdenum dioxide–carbon nanofibers (MoO2–CNFs) using an electrospinning technique. When used as a matrix in sulfur/MoO2–CNF cathodes for Li-S batteries, these nanofibers acted as polysulfide reservoirs to alleviate the shuttle effect and improve electrochemical reaction kinetics during charge–discharge processes. The sulfur/MoO2–CNF composites demonstrated high lithium-ion diffusion coefficients, low interfacial resistance, and better electrochemical performance compared to pristine sulfur cathodes.

Another study synthesized nanocomposites of carbon nanotubes (CNTs) with homogeneously anchored MoO2 nanoparticles using a hydrothermal method. [9] When used as an anode in lithium-ion batteries, these MoO2/CNT nanocomposites delivered a higher reversible capacity compared to MoO3 nanobelt/CNT composites and pure MoO2 nanoparticles. The enhanced performance was attributed to the nanocomposite structure, which efficiently enhanced electrical conductivity, lithium-ion diffusion, and maintained electrode integrity during cycling.

Catalysis

Molybdenum dioxide and related compounds have shown catalytic properties in various reactions. One study investigated supported molybdenum carbide and nitride catalysts for carbon dioxide hydrogenation. [10] The catalysts, prepared by wet impregnation followed by thermal treatment, were able to produce CO, methane, methanol, and ethane from CO2. The carbide activity increased with lower carburizing alkane concentration and temperature, and enhanced performance was obtained with pure anatase titania support.

Another study explored the use of liquid or supercritical carbon dioxide (scCO2) as a reaction medium for ring-opening metathesis polymerization (ROMP) and ring-closing olefin metathesis (RCM) reactions using well-defined metal catalysts, including a molybdenum alkylidene complex. [11] The unique properties of scCO2 provided advantages such as convenient workup procedures, catalyst immobilization, and reaction tuning by density control.

Molybdenum dioxide is a constituent of "technical molybdenum trioxide" produced during the industrial processing of MoS2: [12] [13]

2 MoS2 + 7 O2 → 2 MoO3 + 4 SO2
MoS2 + 6 MoO3 → 7 MoO2 + 2 SO2
2 MoO2 + O2 → 2 MoO3

MoO2 has been reported as catalysing the dehydrogenation of alcohols,<ref doi : 10.1007/BF00914749</ref> the reformation of hydrocarbons [14] and biodiesel. [15] Molybdenum nano-wires have been produced by reducing MoO2 deposited on graphite. [16] Molybdenum dioxide has also been suggested as possible anode material for Li-ion batteries. [17] [18]

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<span class="mw-page-title-main">Oxide</span> Chemical compound where oxygen atoms are combined with atoms of other elements

An oxide is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 that protects the foil from further oxidation.

<span class="mw-page-title-main">Dinitrogen pentoxide</span> Chemical compound

Dinitrogen pentoxide is the chemical compound with the formula N2O5. It is one of the binary nitrogen oxides, a family of compounds that only contain nitrogen and oxygen. It exists as colourless crystals that sublime slightly above room temperature, yielding a colorless gas.

<span class="mw-page-title-main">Vanadium(V) oxide</span> Precursor to vanadium alloys and industrial catalyst

Vanadium(V) oxide (vanadia) is the inorganic compound with the formula V2O5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because of its high oxidation state, it is both an amphoteric oxide and an oxidizing agent. From the industrial perspective, it is the most important compound of vanadium, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst.

Molybdenum trioxide describes a family of inorganic compounds with the formula MoO3(H2O)n where n = 0, 1, 2. The anhydrous compound is produced on the largest scale of any molybdenum compound since it is the main intermediate produced when molybdenum ores are purified. The anhydrous oxide is a precursor to molybdenum metal, an important alloying agent. It is also an important industrial catalyst. It is a yellow solid, although impure samples can appear blue or green.

<span class="mw-page-title-main">Carbon nanofiber</span> Structured carbon fibers

Carbon nanofibers (CNFs), vapor grown carbon fibers (VGCFs), or vapor grown carbon nanofibers (VGCNFs) are cylindrical nanostructures with graphene layers arranged as stacked cones, cups or plates. Carbon nanofibers with graphene layers wrapped into perfect cylinders are called carbon nanotubes.

Potassium hypomanganate is the inorganic compound with the formula K3MnO4. Also known as potassium manganate(V), this bright blue solid is a rare example of a salt with the hypomanganate or manganate(V) anion, where the manganese atom is in the +5 oxidation state. It is an intermediate in the production of potassium permanganate and the industrially most important Mn(V) compound.

<span class="mw-page-title-main">Tungsten disulfide</span> Chemical compound

Tungsten disulfide is an inorganic chemical compound composed of tungsten and sulfur with the chemical formula WS2. This compound is part of the group of materials called the transition metal dichalcogenides. It occurs naturally as the rare mineral tungstenite. This material is a component of certain catalysts used for hydrodesulfurization and hydrodenitrification.

Technetium compounds are chemical compounds containing the chemical element technetium. Technetium can form multiple oxidation states, but often forms in the +4 and +7 oxidation states. Because technetium is radioactive, technetium compounds are extremely rare on Earth.

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<span class="mw-page-title-main">Niobium pentoxide</span> Chemical compound

Niobium pentoxide is the inorganic compound with the formula Nb2O5. A colorless, insoluble, and fairly unreactive solid, it is the most widespread precursor for other compounds and materials containing niobium. It is predominantly used in alloying, with other specialized applications in capacitors, optical glasses, and the production of lithium niobate.

<span class="mw-page-title-main">Pseudocapacitor</span>

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<span class="mw-page-title-main">Molybdate</span> Chemical compound of the form –O–MoO₂–O–

In chemistry, a molybdate is a compound containing an oxyanion with molybdenum in its highest oxidation state of 6: O−−Mo(=O)2−O−. Molybdenum can form a very large range of such oxyanions, which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state. The larger oxyanions are members of group of compounds termed polyoxometalates, and because they contain only one type of metal atom are often called isopolymetalates. The discrete molybdenum oxyanions range in size from the simplest MoO2−
4, found in potassium molybdate up to extremely large structures found in isopoly-molybdenum blues that contain for example 154 Mo atoms. The behaviour of molybdenum is different from the other elements in group 6. Chromium only forms the chromates, CrO2−
4, Cr
2O2−
7, Cr
3O2−
10 and Cr
4O2−
13 ions which are all based on tetrahedral chromium. Tungsten is similar to molybdenum and forms many tungstates containing 6 coordinate tungsten.

<span class="mw-page-title-main">Digermane</span> Chemical compound

Digermane is an inorganic compound with the chemical formula Ge2H6. One of the few hydrides of germanium, it is a colourless liquid. Its molecular geometry is similar to ethane.

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2. Cathodes based on manganese-oxide components are earth-abundant, inexpensive, non-toxic, and provide better thermal stability.

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Neptunium compounds are compounds containg the element neptunium (Np). Neptunium has five ionic oxidation states ranging from +3 to +7 when forming chemical compounds, which can be simultaneously observed in solutions. It is the heaviest actinide that can lose all its valence electrons in a stable compound. The most stable state in solution is +5, but the valence +4 is preferred in solid neptunium compounds. Neptunium metal is very reactive. Ions of neptunium are prone to hydrolysis and formation of coordination compounds.

References

  1. ↑ Snelders, H. A. M. (July 1970). "The Influence of the Dualistic System of Jakob Joseph Winterl (1732–1809) on the German Romantic Era". Isis. 61 (2): 231–240. doi:10.1086/350622. ISSN   0021-1753.
  2. ↑ Lüdtke, Tobias; Wiedemann, Dennis; Efthimiopoulos, Ilias; Becker, Nils; Seidel, Stefan; Janka, Oliver; Pöttgen, Rainer; Dronskowski, Richard; Koch-Müller, Monika; Lerch, Martin (2017-02-20). "HP-MoO2: A High-Pressure Polymorph of Molybdenum Dioxide". Inorganic Chemistry. 56 (4): 2321–2327. doi:10.1021/acs.inorgchem.6b03067. ISSN   1520-510X. PMID   28181799.
  3. ↑ Oxides: Solid state chemistry McCarroll W.H. Encyclopedia of Inorganic Chemistry Ed R. Bruce King, (1994), John Wiley & sons ISBN   0-471-93620-0
  4. 1 2 3 Land, Michael A.; Bačić, Goran; Robertson, Katherine N.; Barry, Seán T. (2022-10-24). "Origin of Decomposition in a Family of Molybdenum Precursor Compounds". Inorganic Chemistry. 61 (42): 16607–16621. doi:10.1021/acs.inorgchem.2c01967. ISSN   1520-510X. PMID   36223133.
  5. ↑ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN   0-471-19957-5
  6. ↑ Conroy, L. E.; Ben-Dor, L. "Molybdenum(IV) Oxide and Tungsten(IV) Oxides Single-Crystals" Inorganic Syntheses 1995, volume 30, pp. 105–107. ISBN   0-471-30508-1
  7. ↑ Sinha, Arun Kumar; Naik, Banoth Vasu (2023-12-14). "Evaluating Performance Using kϕ Index Parameter for a Symmetrical Junction NADGFET: A 3D TCAD Simulation Analysis". 2023 International Conference on Next Generation Electronics (NEleX). IEEE. pp. 1–5. doi:10.1109/nelex59773.2023.10420946. ISBN   979-8-3503-1908-8.
  8. ↑ Kim, Ye Won; Lee, Ae Jin; Han, Dong Hee; Lee, Dae Cheol; Hwang, Ji Hyeon; Kim, Youngjin; Moon, Songyi; Youn, Taewon; Lee, Minyung; Jeon, Woojin (2022). "Correction: Reliable high work-function molybdenum dioxide synthesis via template-effect-utilizing atomic layer deposition for next-generation electrode applications". Journal of Materials Chemistry C. 10 (36): 13268–13269. doi: 10.1039/d2tc90174a . ISSN   2050-7526.
  9. ↑ Qiu, Song; Lu, Guixia; Liu, Jiurong; Lyu, Hailong; Hu, Chenxi; Li, Bo; Yan, Xingru; Guo, Jiang; Guo, Zhanhu (2015-10-13). "Enhanced electrochemical performances of MoO2 nanoparticles composited with carbon nanotubes for lithium-ion battery anodes". RSC Advances. 5 (106): 87286–87294. doi:10.1039/C5RA17147D. ISSN   2046-2069.
  10. ↑ Abou Hamdan, Marwa; Nassereddine, Abdallah; Checa, Ruben; Jahjah, Mohamad; Pinel, Catherine; Piccolo, Laurent; Perret, Noémie (2020). "Supported Molybdenum Carbide and Nitride Catalysts for Carbon Dioxide Hydrogenation". Frontiers in Chemistry. 8: 452. doi: 10.3389/fchem.2020.00452 . ISSN   2296-2646. PMC   7296157 . PMID   32582635.
  11. ↑ Fürstner, A.; Ackermann, L.; Beck, K.; Hori, H.; Koch, D.; Langemann, K.; Liebl, M.; Six, C.; Leitner, W. (2001-09-19). "Olefin metathesis in supercritical carbon dioxide". Journal of the American Chemical Society. 123 (37): 9000–9006. doi:10.1021/ja010952k. ISSN   0002-7863. PMID   11552807.
  12. ↑ Metallurgical furnaces Jorg Grzella, Peter Sturm, Joachim Kruger, Markus A. Reuter, Carina Kogler, Thomas Probst, Ullmans Encyclopedia of Industrial Chemistry
  13. ↑ Shigegaki, Y.; Basu, S. K.; Wakihara, M.; Taniguchi, M. (1988). "Thermal analysis and kinetics of oxidation of molybdenum sulfides". Journal of Thermal Analysis. 34 (5–6): 1427–1440. doi:10.1007/BF01914367.
  14. ↑ Katrib, A.; Leflaive, P.; Hilaire, L.; Maire, G. (1996). "Molybdenum based catalysts. I. MoO2 as the active species in the reforming of hydrocarbons". Catalysis Letters. 38 (1–2): 95–99. doi:10.1007/BF00806906.
  15. ↑ Cuba-Torres, Christian Martin; Marin-Flores, Oscar; Owen, Craig D.; Wang, Zhouhong; Garcia-Perez, Manuel; Norton, M. Grant; Ha, Su (2015). "Catalytic partial oxidation of a biodiesel surrogate over molybdenum dioxide". Fuel. 146: 132–137. doi:10.1016/j.fuel.2015.01.003.
  16. ↑ Zach, M. P.; Inazu, K.; Ng, K. H.; Hemminger, J. C.; Penner, R. M. (2002). "Synthesis of Molybdenum Nanowires with Millimeter-Scale Lengths Using Electrochemical Step Edge Decoration". Chemistry of Materials. 14 (7): 3206–3216. doi:10.1021/cm020249a.
  17. ↑ Shi, Yifeng; Guo, Bingkun; Corr, Serena A.; Shi, Qihui; Hu, Yong-Sheng; Heier, Kevin R.; Chen, Liquan; Seshadri, Ram; Stucky, Galen D. (2009-12-09). "Ordered Mesoporous Metallic MoO2 Materials with Highly Reversible Lithium Storage Capacity". Nano Letters. 9 (12): 4215–4220. doi:10.1021/nl902423a. ISSN   1530-6984. PMID   19775084.
  18. ↑ Kim, Hyung-Seok; Cook, John B.; Tolbert, Sarah H.; Dunn, Bruce (2015-01-01). "The Development of Pseudocapacitive Properties in Nanosized-MoO2". Journal of the Electrochemical Society. 162 (5): A5083–A5090. doi:10.1149/2.0141505jes. ISSN   0013-4651. OSTI   1370243.
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