Preparation of PW12O403−/Cr-TiO2 nanotubes photocatalysts with the high visible light activity

The development of photocatalysts with high visible light photocatalytic activity is of significance. In this study, PW12O403− and Cr3+ modified TiO2 nanotubes, a new type photocatalysts, were prepared with anodization and impregnation methods to increase the visible light catalytic activity of TiO2. The Cr3+ doping narrowed the band gap of TiO2 to enhance the visible light response. Moreover, the Cr3+ doping increased the standard reduction potential of the conduction band electrons of TiO2 enhancing the electron transfer between conduction band electrons from TiO2 (electron donor) and PW12O403− (electron acceptor), so electrons and holes were efficiently separated. The reaction rate constant of PW12O403−/Cr-TiO2 was significantly higher than that of Cr-TiO2 or PW12O403−/TiO2, which was attributed to the synergetic effect between Cr3+ and PW12O403− modification. The synergetic fact of PW12O403− and Cr3+ in PW12O403−/Cr-TiO2(2.36 at%) reached 1.42.