Preparation of Tungsten Oxide Thin Nanosheets

Tungsten oxide thin nanosheets preparation principle is the use of supercritical carbon dioxide device assisted stripping tungstic acid. One supercritical carbon dioxide device is a two-cylinder piston pump, a high-pressure reactor, a heating jacket and a temperature controller.

The thinning of the oxide ultrathin nanosheet is as follows: First, tungstic acid is ground in a mortar and pestle. Then 100 mg of tungstic acid and 100 mg of polyvinyl pyrrolidone are weighed out and poured into 10 ml of a mixed ethanol / water solution (5: 5 by volume). The mixture was sonicated for 2 hours and then poured into a reaction vessel of supercritical carbon dioxide (SC CO2). The temperature was raised to 40 ° C. Carbon dioxide was fed to the reactor to a pressure of 16Mpa. The mixture was kept at 40 ° C under magnetic stirring for 3 hours under a pressure of 16MPa. After the reaction, the carbon dioxide is slowly released until the pressure in the autoclave drops to atmospheric pressure. The solution was then removed and the sonication was continued for 3 hours. The sonified solution was centrifuged at 5000 rpm for 30 minutes to remove unstripped tungstic acid. After that, the supernatant was removed and centrifuged at 20000 rpm for 20 minutes. Precipitate to remove polyvinyl pyrrolidone. Finally, the precipitate is dried at 60 ° C to obtain ultrathin tungsten oxide nanoplatelets.

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