Photocatalytic active tiles: a confirmed industrial reality facing a new challenge with LED lighting

Environmental purification is a necessary aspect of scientific research to improve human life quality. Semiconductor photocatalysis, in particular TiO2 in the anatase form, was intensively investigated for its application to environmental pollutants degradation. A TiO2 photocatalyst that exhibits high activity for the oxidation of VOCs offers an economically and technically practical means to clean air and water. As secondary organic aerosols SOA represents one of the main PM constituents, the ability to break down its precursors would certainly lead to a reduction of PM concentration in the air. In literature, several studies propose linear correlations between NOx and PM10 values. Consequently, NOx degradation immediately contributes to PM reduction. New industrially produced photocatalytic porcelaingrés tiles provide very good photocatalytic performance, but also meet standard requirements with respect to hardness, lack of porosity, vitrified surface and durability. In the preparation, a commercial micro-TiO2 was employed to avoid the use of traditional nano-TiO2 and face no drawbacks due to the possible nanorisks of nanopowders. Unfortunately, TiO2 strongly suffers from the low photocatalytic activity if it is used under visible light and not under UV light. Among the various possible modifications, the surface decoration with metal or metal oxides NPs can be a good strategy to increase the potential of TiO2 in the visible range. A sonochemical method that exploits the use of high-energy ultrasounds is here suggested to obtain this surface decoration. Samples were tested on the photodegradation of NOx, toluene and acetone in gas phase systems, using both UV and LED lamps.