TiO2-based photosensitive oxide semiconductors for solar hydrogen

Titanium dioxide is a promising candidate for high-performance photocatalysts. Defect engineering may be applied for the modification of its properties, including the functional-related properties, in a controlled manner in order to achieve the desired/optimized performance. The present work reports the application of defect engineering for the modification of semiconducting properties of undoped TiO2. The defect disorder is considered in terms of the predominant defect reactions. The related equilibrium constants are used to derive the defect disorder diagram for undoped TiO2 in equilibrium (1273 K) in the gas phase of controlled oxygen activity (10−13 Pa < p(O2) < 105 Pa). The obtaind data on the concentration of electronic charge carriers have been used for the determination of the effect of p(O2) on the change of Fermi energy within the band gap. The determined diagram may be applied for the selection of processing conditions of undoped TiO2 with controlled semiconducting properties and the ability to donate or accept electrons.