The Twenty-first Century is said to be the era of the environment. One of the great features of photocatalyst is the using of solar energy and rain as the main energy without adding burden to the environment. Since the photocatalytic phenomenon has been found, is has been more than 40 years; and about 20 years ago, people discovered that after the mirror glass surface coated with titanium oxide post-treatment, the mirror will not be hazy any more. The reason is that under the bright light, a portion of the oxygen on the mirror surface is removed, so that the water is more easily absorbed, and get closer to the water, creating a flat surface of a water droplet formation, which is super-hydrophilic response.

 

This super hydrophilic effect of photocatalyst is also used in car side rearview mirror. However, since the horizontal on the surface of the photocatalyst slip attached to the precarious situation, if it is placed in the dark situation, it will return to the original state of the surface of titanium oxide. However, if you use both silicon and photocatalyst to carry out a surface coating process, since the silicon is easy to store water, the complementary effects can be brought out.

 

Photocatalyst mainly used in four areas, which are air purification, automatic cleaning, water purification, and antibacterial, sterilization. For example, deodorizing means which uses photocatalytic technology is placed on the smoking plate; rely on the photocatalyst, the photocatalyst air purifier which is mounted on the ceiling can break down acetaldehyde and ammonia in the flue gas; besides, some of the station platform using the photocatalyst added tent; also the artificial flowers’ leaves after the photocatalyst surface coating process, can used for adsorption of smoke in the room air, and so on.

 

Tungsten trioxide is the found and the successful development and mass process, which is a visible light-type photocatalyst with more than 10 times of the conventional photocatalytic activity, it responses the wavelength range of light from 400nm to 800nm . This new type of photocatalyst is added copper ions into tungsten trioxide, electrons move from the tungsten oxide to copper ions during the reaction, copper ions will store electrons and produce an efficient reduction reaction. This high-performance of visible light-type of photocatalyst is believed to play the effects of air purification, pollution prevention, anti-bacterial, anti-viral and so on in indoor environment, moreover, it is expected to have further practical use.

 

With the successful development of high-performance type of visible light photocatalyst, tungsten oxide has been increasingly attended, especially the nano tungsten trioxide, which is the tungsten oxide with a large specific surface area, a significant effect, a special oxidation catalytic performance. As a wide band gap of the n-type semiconductor, nano tungsten oxide photocatalyst is placed very high expectations in the decomposition and elimination of air pollutants, volatile organic compounds (VOC) in indoor air, in addition, stench removal, preventing a worldwide prevalence of infectious diseases, etc..