Photocatalytic reduction of nitrite and nitrate ions over doped TiO<inf>2</inf> catalysts

Doping of TiO2 with altervalent cations, Fe3+, Cr3+, Co2+ and Mg2+ leads to a red shift in the onset of absorption. The role of the dopant ions is primarily to improve the charge separation by means of a permanent electric field. Doping of TiO2 also influences the adsorption of reagent species and the resulting photoactivity is a consequence of these two factors. An optimum level of dopant ions is beneficial for the photocatalytic activity of TiO2. © 1997 Elsevier Science S.A.