Direct growth of ZnO nanowires on civil engineering materials: smart materials for supported photodegradation

Photocatalysis is one of the most promising processes for treating air and water pollution. Innovative civil engineering materials for environmental depollution by photocatalysis have already been synthesized by incorporating TiO₂ or ZnO nanoparticles in cement. This method suffers from two flaws: first, most of the NPs are incorporated into the cement and useless for photocatalysis; second, rain and wind could spread the potentially carcinogenic nanoparticles from the cement surface into nature. Thus, we propose the efficient synthesis of nontoxic and biocompatible ZnO nanostructures solely onto the surface of commercially available concrete and tiling pavements by a low-cost and low-temperature hydrothermal method. Our samples exhibited enhanced photocatalytic activity for degrading organic dyes in aqueous media, and dye molecules are commonly used in the pharmaceutical, food, and textile industries. Durability studies showed no loss of efficiency after four photocatalysis experiments. Such supported structures, which are easy to implement onto the varying surfaces of commercially available materials, are promising for integration into civil engineering surfaces for environmental depollution in our daily life.