Dramatic visible photocatalytic degradation performances due to synergetic effect of TiO2 with PANI.

The dramatic visible light photocatalytic activity was obtained for the degradation of Methylene Blue (MB) and Rhodamine B (RhB) under visible light irradiation (lambda > 450 nm) after TiO2 photocatalysts were modified with monolayer dispersed polyaniline (PANI) via a facile chemisorption approach. Under visible light irradiation, PANI generated pi-pi* transition, delivering the excited electrons into the conduction band of TiO2, and then the electrons transferred to an adsorbed electron acceptor to yield oxygenous radicals to degrade pollutants. Also, the ultraviolet photocatalytic performance was enhanced to about two times compared with that of P-25 TiO2 photocatalyst. The high photocatalytic activity came from the synergetic effect between PANI and TiO2, which promoted the migration efficiency of photogenerated carriers on the interface of PANI and TiO2. Under ultraviolet light irradiation, photoinduced holes in TiO2 valence band could transfer into HOMO orbital of PANI and then emigrate to the photocatalyst surface and oxidize the adsorbed contaminants directly. The optimum synergetic effect was found at a weight ratio of 3.0 wt % (PANI/ TiO2).