Visible light active N doped GeO2 for the photodegradation of both anionic and cationic dyes

We report the photocatalytic activity of a visible light active N doped GeO2 (NG), which can degrade Rhodamine B (cationic) and Acid violet 7 (anionic) dyes efficiently from aqueous solutions. A considerable red-shift in the absorption edge is seen for NG compared to pure GeO2 due to N doping. Presence of bonded nitrogen in the doped sample is clearly seen from X-ray photoelectron spectroscopy. NG exhibits higher degradation rate for cationic, Rhodamine B as compared to anionic, Acid violet 7 dyes. Studies with quenchers indicate that superoxide radical is the main active species involved in photocatalytic degradation of Rhodamine B. (C) 2013 Elsevier B.V. All rights reserved.