Tiocem is a specialized cement with photocatalytic features, used on the surface of buildings to reduce air pollution caused by exposure of the cement to ultraviolet light (UV).

Photocatalysis is initiated by titanium dioxide (TiO₂), which is added during the cement’s production. Typical properties (i.e. strength) of cement applications (such as concrete) will be added to clean the air around the photocatalytic surface. Nitrogen dioxide (NO₂) will be particularly abated when daylight activates the photocatalytic surfaces.

The chemical process may be summarized as follows:

TiO₂ + hν -> TiO₂ + h+ + e-

H₂O + h+ -> H+ + OH-

Using materials like Tiocem, the abatement of NO₂ could be measured by a test method using the Italian standard UNI 11247, which is being discussed as the basis of a European standard. This method involves test apparatus in which a mixture of air and pollutant flows in a chamber over a test object; the pollutant burden is measured with (and without) exposure to light. A defined level of NO₂ abatement is guaranteed by the label “TX Active” (plus an initial) and replication of the test results. Proof of the effective reduction of oxide-of-nitrogen exposure has been furnished under close-to-practical conditions by the PICADA (Photocatalytic Innovative Coverings Applications for Depollution Assessment) Project (supported by the European Union and other studies.