Visible-light responsive dye-modified TiO2 photocatalyst

A series of dye-modified TiO2 photocatalysts were synthesized using dye Chrysoidine G (CG), tolylene-2,4-diisocyanate (TDI), and commercial TiO2 (Degussa P25) as starting materials. TDI was used as a bridging molecule whose two -NCO groups reacted with Ti-OH of TiO2 and -NH2 groups of CG, respectively. As a result, special organic complexes were formed on the TiO2 surface via stable pi-conjugated chemical bonds between TiO2 and dye molecules, confirmed by FT-IR, XPS, and UV-vis spectra. Due to the existence of pi-conjugated surface organic complexes, the as-synthesized photocatalysts showed a great improvement in visible absorption (400-550 nm). Methylene blue, as a photodegradation target, was used to evaluate the photocatalytic performance, and the dye-modified TiO2 exhibited much better activity under the visible light irradiation than bare TiO2. (C) 2008 Elsevier Inc. All rights reserved.