Photocatalyst, also known as photocatalyst, is a kind of semiconductor material with photocatalytic function represented by nano-titanium dioxide. The representative photocatalyst material is titanium dioxide, which can produce strong oxidizing substances (such as hydroxyl radical, oxygen and so on). ) Under illumination, it can be used to decompose organic compounds, some inorganic compounds, bacteria and viruses.

More than a dozen photocatalyst materials have been studied, such as titanium dioxide, zinc oxide, cadmium sulfide, WO3, iron oxide, lead sulfide, tin oxide, indium oxide, zinc sulfide, strontium titanate and silicon dioxide. These semiconductor oxides have certain photocatalytic degradation activity and are stable and non-toxic. Because most of them are prone to chemical or photochemical corrosion, they are not necessarily suitable as general photocatalyst.

Extended data

Photocatalyst generates hydroxyl radicals after being irradiated, which react with organic substances in the air to generate nontoxic inorganic substances, which can effectively decompose formaldehyde, benzene series, volatile organic compounds, ammonia, sulfur dioxide, carbon monoxide, nitrogen oxides, automobile exhaust and other toxic substances that affect human health. In photocatalysis, organic matter is decomposed into carbon dioxide and water, thus purifying the air.

The experimental results show that the degradation of air pollutants by photocatalyst is related to its concentration. Formaldehyde in low concentration can be completely decomposed into H2O and CO2 by photocatalyst, while in high concentration, it is first oxidized into intermediates such as HCOOH, and then decomposed into H2O and CO2.

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