Molybdenum disulfide is an inorganic compound composed of molybdenum and sulfur. The main source of MoS2 is molybdenite. Molybdenum disulfide is a black solid powder with a metallic luster. It has a melting point of 1185 ° C, a density of 4.80 g/cm 3 (14 ° C), and a Mohs hardness of 1.0 to 1.5.
Molybdenum disulfide is prepared by chemically purifying natural molybdenum concentrate powder to change its molecular structure. It is insoluble in water. The product has the advantages of good dispersibility and non-binding and can be added to various greases to form a colloidal state which is never bonded and can increase the lubricity and extreme pressure of the grease. It is also suitable for high temperature, high pressure, high speed, and high load mechanical working conditions to extend equipment life. The main function of molybdenum disulfide for friction materials is to reduce friction at low temperatures, increase friction at high temperatures, and reduce ignition loss, which is volatile in friction materials.
Preparation of Molybdenum Disulfide
The molybdenum concentrate is prepared by repeatedly stirring with hydrochloric acid and hydrofluoric acid under direct steam heating, washing with hot water, centrifuging, drying, and pulverizing. Hydrogen sulfide gas is introduced into the ammonium molybdate solution to form ammonium thiomolybdate. Hydrochloric acid is added to the precipitate of molybdenum trisulfide, followed by centrifugation, washing, drying, and pulverization. Finally, molybdenum disulfide can be obtained by heating it to 950 °C for desulfurization.
Application of Molybdenum Disulfide
Molybdenum disulfide can also be a new material for making transistors. Compared with graphene of the same two-dimensional material, molybdenum disulfide has a band gap of 1.8 eV, while graphene has no band gap. Therefore, molybdenum disulfide may have a wide application space in the field of nano-transistors. Moreover, the single-layer molybdenum disulfide transistor has an electron mobility of up to about 500 cm^2/(V·s) and a current switching rate of 1×10^8.
Molybdenum disulfide is an important solid lubricant and is especially suitable for high temperatures and high pressure.
It is also diamagnetic and can be used as a linear photoconductor and a semiconductor exhibiting P-type or N-type conductivity, with the function of rectification and transduction.
Molybdenum disulfide can also be used as a catalyst for the dehydrogenation of complex hydrocarbons.