Nano tungsten oxide can not soluble in water itself, the so called nano tungsten oxide aqueous solution is the dispersion which nano tungsten oxide particles are uniformly distributed in water, to play the roles of oxidization and reunion of tungsten oxide. Tungsten oxide is the typical transition metal oxides, while the nano tungsten oxide is a new type of functional material, and because of its excellent discoloration performance, it can be widely used in many fields, such as intelligent window, large area flat panel display, gas sensor, dye-sensitized solar cell, automatic mirror, energy storage.
Ammonium metatungstate (AMT) is the important intermediate compound of tungsten metallurgy, and being the important raw material for manufacturing tungsten oxide, tungsten and tungsten carbide powder and other tungsten products. An invention has proposed one method to prepare nano tungsten oxide aqueous solution from the raw material of ammonium metatungstate and sodium borohydride, with the steps like bellows:
1. Weight the appropriate amount of ammonium metatungstate and sodium borohydride according to the mass ratio of 1~10:1;
2. Add the AMT powder into deionized water to dissolve with stirring and get the ammonium metatungstate aqueous solution with the concentration of 5~50%;
3. Add the weighted sodium borohydride solid into the AMT solution and stir to mix them uniformly, stay to react for 10~60 minutes under the room temperature to 95°C to get the blue nano tungsten oxide aqueous solution with 0.1〜10nm uniform particle size. since the ammonium metatungstate will react with sodium borohydride to generate blue nano WO2.9, and it will release heat, a large number of hydrogen gas and ammonia gas during the reaction process, which will remove purity of ammonium ion.
Nano tungsten oxide aqueous solution prepared by this method has the advantages of good stability, small particle size of nano tungsten oxide and others, thus to have wide application in intelligent window, gas sensor and solar energy cell and other fields.