Progress made in the defect chemistry of TiO2 and its solid solutions with aliovalent ions forming donors and acceptors was reported. The relationship between the defect-related properties, such as electrical and photocatalytic properties, were outlined. It was shown that reactivity, photoreactivity, and the related charge transfer of photocatalysts based on TiO2 were determined by defect disorder and the related chemical potential of electrons. Therefore, defect chemistry may be used as a framework for the processing of well-defined TiO2-based photocatalysts. The photoreactivity of TiO2 with water and its solutes was considered in terms of the effect of both collective and local properties. The effect of noble metals attached to TiO2 as a separate phase, such as platinum, on photo-electrochemical properties and the related photocatalytic performance of TiO2 was discussed. The key functional properties, which were responsible for the efficient conversion of solar energy into chemical energy (required for water purification), were outlined. The effect of TiO2 doping with aliovalent ions on properties was considered in terms of the doping mechanisms and the related semiconducting properties. It was argued that comparison of the experimental data reported in the literature on the photocatalytic properties of TiO2 dictates the need to establish standards for photocatalysts, which were well-defined. This paper reports the processing conditions of well-defined TiO2. It was argued that knowledge of the mass transport kinetic data, such as chemical and self-diffusion coefficients, was needed for selecting the optimal processing conditions.

Defect Chemistry of Titanium Dioxide. Application of Defect Engineering in Processing of TiO2-Based Photocatalysts. Nowotny, M.K., Sheppard, L.R., Bak, T., Nowotny, J.: Journal of Physical Chemistry C, 2008, 112[14], 5275-300