What is a visible light photocatalyst

Photocatalyst is a general term for photosemiconductor materials with photocatalytic function represented by nanoscale titanium dioxide, which is coated on the surface of the substrate and produces a strong catalytic degradation function under the action of ultraviolet light and visible light: it can effectively degrade toxic and harmful gases in the air; It can effectively kill a variety of bacteria, and can decompose and harmless the toxins released by bacteria or fungi; At the same time, it also has the functions of formaldehyde removal, deodorization, anti-fouling, and air purification.

As the name suggests, photocatalyst formaldehyde removal requires the participation of light, especially ultraviolet light, as a catalyst, the photocatalyst itself does not participate in the reaction, but there must be the participation of light, so the photocatalyst in the removal of formaldehyde is generally used in the removal of formaldehyde in industry, such as the formaldehyde treatment of plates in the board factory, as well as leather, prevention, and the place where formaldehyde needs to be treated in industrial production.

In recent years, some photocatalysts have been used in formaldehyde treatment in the home environment, in fact, this is not suitable, because the participation of light in the indoor environment is not very sufficient, and the formaldehyde treatment used in the indoor environment is easy to produce secondary pollution and incomplete formaldehyde decomposition. In developed countries in Europe, indoor formaldehyde treatment is generally removed with photophyllin, which originates from the photoreceptor molecules of green plants, and can decompose formaldehyde even in an indoor environment, even in a very weak light environment, and more importantly, it can be completely decomposed.

Photocatalyst, also known as photocatalyst, is a general term for semiconductor materials with photocatalytic functions represented by nanoscale titanium dioxide. The representative photocatalyst material is titanium dioxide, which can produce strong oxidizing substances (such as hydroxyl radicals, oxygen, etc.) under light irradiation, and can be used to decompose organic compounds, some inorganic compounds, bacteria and viruses.

The commonly used photocatalyst materials are mainly n-type semiconductor materials, which have the characteristics of low band gap, and the commonly used photocatalyst semiconductor materials are titanium dioxide. ZRO2, ZNO, CDS, WO3, Fe2O3, PBS, SNO2, ZNS, SRTIO3, SiO2, etc. are also photocatalyst materials. In daily life, photocatalysts can effectively degrade toxic and harmful gases in the air, such as formaldehyde, and efficiently purify the air; At the same time, it can effectively kill a variety of bacteria, and can decompose and harmless the toxins released by bacteria or fungi.

The degradation of air pollutants by catalysts is related to their concentrations, and low concentrations of formaldehyde can be completely decomposed into H2O and CO2 by photocatalyst photocatalysis, while at higher concentrations, they are first oxidized to HCOOH and other intermediates, and then decomposed into H2O and CO2.

Under light conditions, photocatalysts can cause redox reactions and gradual degradation of hydroxyl groups, halogenated substances, carboxylic acids and other substances in water, and finally become harmless small molecule substances. Under sunlight, the removal efficiency of olive oil wastewater treated with nano-TiO2 loaded sepiolite reached 80%.