Bismuth Tungstate Hollow Spheres Preparation

Hollow sphere is a kind of material with special structure from nanometer to micrometer in size. Because of its low density, large specific surface area, good stability and surface permeability, these materials have important applications in chemistry, biology and materials science.

Hollow spherical shells and porous materials accumulated from hollow spherical shells have great potential applications in catalysis, packaging of sustained-release drugs, simulation of artificial cells, coating and protection of biological active molecules such as proteins, enzymes, DNA, and as coatings or pigments, etc. They have become attractive materials in the field of materials research. One of the directions of attention. Bismuth tungstate (Bi₂WO₆) is an n-type semiconductor material. It has been widely used in many fields such as electrical insulation, ionic conductivity, luminescence and photocatalysis. In order to improve the catalytic performance of Bismuth tungstate, some scholars have successfully prepared Bi₂WO₆ hollow spheres by simple and feasible methods. The process includes the following steps:

Saturated sodium tungstate aqueous solution and saturated bismuth nitrate aqueous solution are disposed respectively. Under the condition of continuous stirring, 15 mL saturated sodium tungstate solution was added to 120 mL absolute ethanol to form suspension. Under the condition of continuous stirring, 15 mL saturated bismuth nitrate aqueous solution was added to 120 mL absolute ethanol to form a suspension. Then they are mixed, stirred slowly for 30 minutes, then heated to 100 ℃ in a sealed reactor for 12 hours. The solid phase substances produced by the reaction were collected, and the white powder products were obtained after separation and washing. The product was identified as bismuth tungstate by X-ray diffraction analysis and hollow sphere structure by transmission electron microscopy. The particle size was about 50 nm and the wall thickness was about 10 nm.

The preparation method of bismuth tungstate hollow spheres does not need to add other substances besides reactants as templates, nor need to produce water-insoluble intermediate products as templates through chemical reactions. Instead, the water-soluble bismuth salts (bismuth nitrate, bismuth chloride, etc.) are directly prepared from water-soluble reactants in polar organic solvents (ethanol, acetone, etc.). The solid particles precipitated in the template are used as the template, which is converted into the target product bismuth tungstate hollow sphere in the subsequent interfacial reaction. The method has wide applicability, mild conditions, simple process and is easy to industrialize.

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