Efficient self-cleaning treatments for built heritage based on highly photo-active and well-dispersible TiO2 nanocrystals

The new treatment exhibits higher photocatalytic activity compared to that based on commercial TiO2 (P25_TiO2). This behavior has been attributed not only to the morphological properties of the treatments and of the stones, but also to the presence of residual benzyl alcohol molecules anchored on the anatase NP surfaces. This provides solar light absorption and partially improves the charge trapping, thus increasing the photoefficiency. The overall results suggest that the positive combination of high dispersion, solar-light absorption and reduced recombination effects in NPs plays a key role in the development of efficient photocatalytic treatments for stone restoration.