Titanium Dioxide Nanoparticles and Nanostructures

Titanium dioxide (TiO2) is the most intensely investigated photocatalyst and until today the only one that has already been commercialized and that is involved in many applications such as self-cleaning materials, dye-sensitized solar cells, as well as water and air purification. Consequently, an exponential growth of research activities concerning the nanoscience and nanotechnology of TiO2 has been observed during the last decades. These raising research activities have recently lead to the synthesis of nanosized TiO2 single crystals with well-defined shapes and with specific exposed surfaces. Thus, the present review will focus mainly on the synthesis of these nanomaterials. The thermodynamic stability, the transition between different TiO2 polymorphs, and the surface properties of these polymorphs are presented with the aim to utilize these informations for a better understanding of the mechanism of the formation of shape-defined TiO2 nanomaterials and their various applications in photocatalysis.