Rev.Adv.Mater.Sci. (RAMS)
No 2, Vol. 51, 2017, pages 91-129


Pedro Magalhães, Luísa Andrade, Olga C. Nunes and Adélio Mendes


TiO2 semiconductor is being investigated and used for different applications such as energy production, photoinactivation, photoabatement, self-cleaning and water desalination. TiO2 has, however, a large band gap, ca. 3.2 eV, which limits its absorption to UV light range that accounts only for ca. 5% of the solar spectrum energy. Therefore, strategies for reducing its band gap aiming to enhance visible light harvesting and making TiO2 usable for indoors applications are being studied; this reduction is mainly achieved by doping and decoration. More recently, TiO2/graphene composite proved to be an interesting material for photocatalytic purposes, presenting enhanced energy harvesting properties and an improved photocatalytic activity. Furthermore, the micro size of the composite graphene platelets allows its use without the potential health hazards associated to TiO2 nanoparticles. TiO2 may contribute to prevent nosocomial infections because, similarly to the phagocytic cells of the human immune system, it uses the cytotoxic effects of Reactive Oxygen Species (ROS) to inactivate microorganisms. These ROS are known to be highly reactive with biological molecules and thus they are effective for the inactivation of various types of microorganisms. The photocatalysis fundamentals and the preparation of more efficient TiO2 photocatalysts suitable for indoor applications are reviewed aiming their application for the photoinactivation of microorganisms. Additionally, a comparison of the effectiveness of photoinactivation with traditionally used disinfection methods is also made. Finally, gaps in the knowledge on the long-term effect of the utilization of TiO2 based materials are identified.

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