Solvothermal Synthesis of Tungsten Diselenide Nanosheets in One Step

As the main transition metal selenide, tungsten diselenide (WSe₂) is a kind of engineering material and functional material with many special properties. WSe₂ crystal has a hexagonal sandwich structure similar to MoS₂. Each WSe₂ molecule layer is composed of two Se atom layers with a W atom layer. The W atom layer and Se atom layer are covalently bonded, while the adjacent WSe2 layers are separated by Se layer with a long distance and a weak van der waals force.

WSe₂ as the main transition metal selenide, high temperature resistance, decomposition temperature up to 850 ℃; acid and alkali resistance and other media, good stability; good lubrication performance, WSe₂ is also diamagnetic p-type semiconductor material, low conduction band (1.16eV), is the lowest thermal conductivity material in the world, the energy conversion efficiency of the system is high, so this new material will be high temperature solid lubrication, high efficiency too. Solar batteries, new energy storage materials, high performance insulating ceramics and the next generation of high performance transistors have broad application prospects.

Some scholars have developed a one-step synthesis process of tungsten diselenide nanosheets by solvothermal method, using cheap selenium powder as selenium source, sodium tungstate as tungsten source, sodium borohydride as reducing agent and organic solvent as reaction solvent.

Step 1: Dissolve 0.1513g sodium borohydride in 50ml N, N-dimethylmethylamine, mix evenly, add 0.3632g selenium powder to stir until completely dissolved, then add 0.6597g sodium tungstate to prepare mixed solution.

Step 2: Transfer the mixed solution obtained in step 1 to the PTFE reactor and react for 48 hours at 200 ℃.

Step 3: After the temperature of the reactor in step 2 is naturally cooled to room temperature, the black products are collected by filtration and washed with deionized water and ethanol respectively. Tungsten diselenide nanosheets are obtained after freeze-drying for 24 hours.

Compared with the existing preparation methods, the one-step synthesis of tungsten diselenide is simple in process, green in raw materials, low in cost and mild in reaction conditions. The obtained tungsten diselenide nanosheets have high crystalline quality, uniform size distribution and high specific surface area. The thickness of the nanosheets is less than 10 nm. It is expected that the nanosheets will have very good application prospects in catalysis, energy storage and other fields.

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