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Titanium dioxide (TiO 2) absorbs only a small fraction of incoming sunlight in the visible region thus limiting its photocatalytic efficiency and concomitant photocatalytic ability. The large-scale application of TiO 2 nanoparticles has been limited due to the need of using an ultraviolet excitation source to achieve high photocatalytic activity. The inclusion of foreign chemical elements in the TiO 2 lattice can tune its band gap resulting in an absorption edge red-shifted to lower energies enhancing the photocatalytic performance in the visible region of the electromagnetic spectrum. In this research work, TiO 2 nanoparticles were doped with iron powder in a planetary ball-milling system using stainless steel balls. The correlation between milling rotation speeds with structural and morphologic characteristics, optical and magnetic properties, and photocatalytic abilities of bare and Fedoped TiO 2 powders was studied and discussed.

h i g h l i g h t s Photocatalytic, superhydrophobic and self-cleaning capabilities were promoted on asphalt mixtures. AC 6 and AC 14 mixtures were coated with TiO 2 and/or ZnO aqueous solutions by spraying. Physicochemical and morphological properties of bitumen samples were evaluated by FTIR and AFM. New pavement surface capabilities assessed with Water Angle Contact and Photocatalytic Efficiency tests. No deterioration was guaranteed for AC 14 TiO 2 , AC 14 TiO 2 ZnO, AC 6 TiO 2 and AC 6 TiO 2 ZnO solutions.

Nowadays, there is increasing concern in transportation engineering about the use of techniques less harmful to the environment and also about road safety. Heterogeneous photocatalysis based on the application of semiconductor materials onto asphalt mixtures is a promising technology because it can mitigate air pollution and road accidents. The functionalized asphalt mixtures with photocatalytic capability can degrade pollutants, such as damaging gases and oil/grease adsorbed on their surface, from specific reactions triggered by sunlight photons, providing significant environmental and social benefits. In this article, a review of photocatalysis applied in asphalt mixtures is presented. The most important characteristics related to the functionalization of asphalt mixtures for photocatalytic applications and their corresponding characterization are presented, and the achieved main results are also discussed.