What is photocatalysis?


Photocatalysis is the acceleration of a photoreaction in the presence of a catalyst.

Photo = light: energy source for the reaction

Forms of light:

Ultra-violet light (< 380 nm): special lamps or outdoor light

Visible light (380 >< 740 nm)



Catalyst = TiO²: a substance which accelerates a chemical reaction, but which itself is not consumed by the overall reaction.

When this photocatalyst is exposed to light in the presence of water vapor formation of two highly reactive substances:

Hydroxyl radicals (OH-)

Superoxide anion (O2-1)

This reaction creates an oxidation process which reduces all type of pollutants present in the air to less pollutant components such as carbon dioxide and water.


Light access

Pollutant access

Pollutant removal



Light intensity

Relative humidity

Specific surface

Contact time