Preparation of AgI sensitized amorphous TiO₂ as novel high-performance photocatalyst for environmental applications

A novel visible-light-active material was prepared by dispersion of AgI on amorphous TiO2 through simple one-pot process (AgI/Am-TiO2-S). For comparison, AgI sensitized TiO2 (amorphous, anatase and P25) were also prepared via traditional deposition-precipitation method. The samples were characterized by XRD, XPS, TGA-DSC, UV-Vis-DRS, BET, and etc. Larger specific surface area, negative shift of flat band potential, as well as greatly reduced charge transfer resistance were observed for AgI/Am-TiO2-S comparing to other samples. Moreover, with the same molar of initial Ti and Ag, the weight of AgI/Am-TiO2-S obtained was the heaviest, due to large amount of surface titania hydrate. The photocatalytic activity of the as-prepared AgI/titania samples were evaluated by the reduction of Cr(VI) in the absence or presence of organic pollutants (dyes, phenol). AgI/Am-TiO2-S always presented the highest photocatalytic activity. The estimated k(Cr(VI)) on AgI/Am-TiO2-S was about 2 times that on AgI/P25-TiO2 in the absence/presence of RhB. Superior stability was also observed in the cyclic runs indicating that the as-prepared AgI/Am-TiO2-S is highly desirable for the remediation of Cr(VI)-organic co-contaminated wastewaters.