Photocatalytic degradation of organic additives contained in TiO2-photocatalytic paints

Introduction \nTitanium dioxide is frequently used in outdoor building materials to degrade, when activated by sunlight, organic and inorganic pollutants in the air. In this context, one application is use of TiO2 in photocatalytic paints.\n\nThe development of doped TiO2 (e.g. with Mn) which can be activated by artificial light opened up a wide range of air-purifying applications in indoor environments too. Examples include TiO2-based paints, wallpaper containing TiO2 and textiles. In particular, TiO2-based paints described as possessing ‘indoor air-purifying’ properties have been launched on the market in recent years.\nHowever, the use of novel products like these has to be free of undesired side-effects such as the formation of byproducts which might impair comfort and well-being indoors.\n\nConclusions\nThe organic components of paints such as binders and additives are decomposed due to photocatalytic processes. This self-degrading effect results in emissions of aldehdyes and ketones in the indoor environment and therefore potentially contributes to a deterioration of air quality. To be commercially attractive, photocatalytic paints should maintain high photocatalytic activity while preventing self-degradation. The chemical stability of the supporting material against photocatalytic degradation can be increased by thoughtful selection of the ingredients used.