The influence of transition metal doping on the physical and photocatalytic properties of titania

Titanium dioxide is one of the most efficient photocatalysts for the detoxi fication of organically charged waste water. However, this material suffers from the drawback of poor absorption properties because of a band gap of 3 .2 eV. Thus, wavelengths shorter than 400 nm are needed for light induced g eneration of electron-hole pairs. Therefore, doping with transition metal i ons is interesting for inducing a bathe-chromic shift of the band gap. Howe ver, this doping changes other physical properties such as lifetime of elec tron-hole pairs and adsorption characteristics. This paper deals with dopin g titania by Cr3+ and Mo5+ ions. We want to show the complex interactions b etween variations in lifetime of charge carriers, adsorption properties and photocatalytic behaviour. (C) 1999 Elsevier Science S.A. All rights reserv ed.