Titanium dioxide: Structure, properties and applications

Since its commercial production in the early twentieth century, titanium dioxide (TiO₂) has been widely used as a pigment and in sunscreens, ointments, paints, toothpaste, etc. about 100 years. The morphology and nanostructure of TiO₂, which are very important to their applications, are significantly influenced by the preparative conditions and methods. In 1972, Fujishima and Honda discovered the phenomenon of photocatalytic splitting of water on a TiO₂ electrode under ultraviolet (UV) light. Since then, enormous efforts have been devoted to the research of TiO₂ material, which has led to many promising applications in areas ranging from photovoltaics and photocatalysis to photo-/electrochromics and sensors. These applications can be roughly divided into "energy" and "environmental" categories, many of which depend not only on the properties of the TiO₂ material itself but also on the modifications of the TiO₂ material host (e.g., with inorganic and organic dyes) and on the interactions of TiO₂ materials with the environment.