With the development of chemical engineering technology, there are a series of synthesis methods used to produce nanometer scale pure molybdenum carbide (chemical formula MoC) , the followings are five common preparation methods:
1.0 Temperature programmed reduction method
The temperature programmed method raised in the 1980s is still the most widely used method to obtain MoC in the laboratory, during the reaction experiment, molybdenum oxide is used as molybdenum source, hydrocarbon gas and hydrogen are used as basic materials for carbon dioxide and gas reduction respectively, and the temperature rises slowly to ensure the catalytic speed balancing in the reaction process. The composition and content of tail gas are monitored by chromatography, and the reaction process is evaluated according to the results. The reaction with carbonized raw materials is stopped in time to obtain MoC with large surface area. The carbon source of these catalytic reactions comes from cracking products and hydrogen reaction of hydrocarbon gas at high temperature.
2.0 Microwave pyrolysis method
Microwave heating is rapid, the system temperature can reach the set value in a short time, so the preparation time of molybdenum carbide can be reduced to another level, which can effectively inhibit the hot particle phenomenon, so that MoC can be obtained from microwave solution, and the particles are uniform and small in size.
3.0 Chemical vapor deposition method
Chemical vapor deposition is the treatment technology in which chemical reactions happen in the vapor phase to deposit solids on the surface of heated solid substrate. This is a kind of processing technology that can efficiently prepare thin films under heavy load. Some researchers use two-step precipitation method and carbon dioxide formation method to obtain MoC thin layer.
4.0 Sol gel method
Heat the gel and evaporate at 60℃～80℃, and then heat in hydrogen at 850℃ for 14h to obtain six square MoC. In addition, nickel and nickel carbide can be produced by adding appropriate amount of nickel acetate, which can be used to modify MoC.
5.0 Biomass Carbonization Method
In recent years, the method of extracting carbides from biomass is very popular. There are many types of biomass including renewable resources, so it can be used for mass production of carbides. Because the carbon dioxide reaction occurs between the solid phase and the solid phase, it is easy to control.
