Theoretical study of the modification of the oxide-reducing capacity of titania from selected dopant elements

Abstract

The positions of the upper edge of the valence band and the lower edge of the conduction band of semiconducting materials such as TiO2 are closely related to the values of the respective oxidation or reduction potentials. The modifcations sufered by a material of this type impact on the displacements of the aforementioned bands and thus on the redox potentials. In the present work, anatase and rutile bulk systems are analyzed for how diferent metallic and nonmetallic dopants located substitutionally where the “@” symbol indicates that the preceding element replaces the element after it or interstitially this position in the network is indicated with the letter “i” afect these potentials. From the analysis of the modifcations, consequence of the doping, it can be noted that substitutional doping of nitrogen (N) at the oxygen site (N@O) improves the reduction potential of anatase and doped with interstitial (Ni) that of rutile. On the other hand, for both polymorphs, interstitial iron (Fei) doping has the best oxidant properties, followed by doping with Fe in titanium (Ti) site (Fe@Ti). The latter also has interesting magnetic properties to facilitate the extraction of the titania from the reaction media. The other doping elements studied, vanadium, platinum, silver, carbon and fuorine only improve the oxidation potential but all to a lesser extent than iron.