Tungsten Oxide Surface Effect

The surface effect means that when the tungsten oxide particles are in the small size range of 1-100 nm, as the diameter of the tungsten oxide particles becomes smaller, the number of atoms on the surface of the nano particles is rapidly increased.

Tungsten oxide materials, the specific surface area, surface energy and surface binding energy will be significantly increased, showing the different properties of tungsten oxide materials. As the particle size of tungsten oxide decreases, the number of atoms on the surface increases rapidly, and many dangling bonds are formed due to the lack of adjacent atoms around newly emerging surface atoms. This unsaturation stabilizes nanoparticles in combination with other atoms in the surrounding environment and thus exhibits high chemical activity. This phenomenon is the surface effect of tungsten oxide material. At the same time, the increase of surface area can provide more reactive sites for the reaction, so the application range of tungsten oxide particles can be improved by improving the surface effect of the tungsten oxide particles.

The surface area of tungsten oxide particles is proportional to the square of the diameter. The volume of the tungsten oxide particles is proportional to the cube of the diameter, so the specific surface area is inversely proportional to the diameter. As the diameter of the tungsten oxide particles becomes smaller, the specific surface area will be significantly increased, and the number of atoms on the surface of the particles will be relatively increased. So that these surface atoms with high activity and very unstable, resulting in tungsten oxide particles show a different character. As the tungsten oxide material decreases in particle size, the number of surface atoms rapidly increases. For example, when the particle size is 10 nm, the number of surface atoms is 20% of the total number of complete crystal atoms.

The particle size of 1nm, the atomic percentage of its surface increased to 99%. At this time, all about 30 atoms that make up the nanocrystalline grains are almost entirely distributed on the surface. Due to the lack of adjacent atoms around the surface atoms. It has many dangling bonds, with unsaturation, easy to stabilize with the combination of other atoms, it shows high chemical activity. With the decrease of particle size, the surface area, surface energy and surface binding energy of nanomaterials increase rapidly.

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