The effect of ageing and re-activation of titania-containing building materials, as investigated by X-ray Photoelectron Spectroscopy

Titanium dioxide, the most promising photocatalyst, is becoming part of innovative commercial products in the main areas of energy and environment. A series of commercially available paintings containing anatase, which are proposed to help reducing indoor and outdoor environmental pollution, has been studied with X-ray Photoelectron Spectroscopy. XPS allows for elemental analysis and relative quantitative analysis at the level of single oxidation states in the first 1-5 nm from the surface. The samples have been studied in their progressive ageing with exposure to light and the atmosphere. Further to this step, they have been subjected to re-activation tests in visible light and eventually to ultraviolet light. All the above steps have been characterized with XPS. Various effects have been disclosed, relevant for an understanding of these innovative materials.