Fabrication of titanium dioxide and tungstophosphate nanocomposite films and their photocatalytic degradation for methyl orange.

Photocatalytic multilayer films with different numbers of bilayers were prepared via an electrostatic layer-by-layer (LbL) self-assembly method. These LbL films were characterized by UV-vis spectroscopy, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Our results indicate that TiO(2) and tungstophosphate (H(3)PW(12)O(40), abbreviated as PW(12)) are successfully incorporated into the thin films. The as-prepared (TiO(2)/PW(12))(n) films show good photocatalytic performance toward methyl orange (MO) solution at pH 2.0, which is attributed to the synergistic effect between TiO(2) and PW(12). The effect of experimental parameters including number of bilayers, initial concentration, and pH value of dye solution were also studied. The multilayer films can be easily recovered and reused several times with little change of degradation, indicating that they are stable under the ultraviolet (UV) irradiation. The detection of active species displays that active holes (h(+)) play a dominant role for MO photodegradation in the TiO(2)/PW(12) system. Taking advantage of immobilization of catalysts on glass slides, the problem of recovery is solved. It is expected that photocatalytic multilayer films have substantial applications in industry.