Photo-catalytic efficiency of laboratory made and commercially available ceramic building products

Self-cleaning building products are mainly based on the application of nanotitania onto exposed outdoor surfaces. In order to achieve high self-cleaning efficiency for outdoor applications, it is important that nanotitania is in the form of anatase, and that particle sizes (also in the case of additional thermal treatment) are in the nano-range, so that a large enough specific surface area can be activated. The particle size and the mineralogy of the photocatalytic layers were determined by means of SEM and Raman spectroscopy, respectively. The self-cleaning efficiency of nanotitania-based material can be evaluated by different methods; in the present paper the suitability of the method based on the discolouration of methylene blue was verified on some samples that were prepared in-lab (through the application of commercially available TiO2 sol onto a ceramic substrate), as well as on samples of commercially available products.