Synthesis and photoactivity of the highly efficient Ag species/TiO2 nanoflakes photocatalysts

Ag species/TiO2 nanoflakes photocatalysts with different relative contents (Ag+, Ag2+, Ag-0) have been successfully synthesized by a simple template-free synthetic strategy. X-ray photoelectron spectroscopy, X-ray diffraction, and UV-vis diffuse reflectance spectra indicated that the dopant ions (Ag+ or Ag2+) were partly incorporated into the titanium dioxide nanoflakes. Meanwhile, part of the silver ions migrated to the surface after the subsequent calcination and aggregated into ultra-small metallic Ag nanoclusters (NCs) (1-2 nm), which are well dispersed on the surface of TiO2 nanoflakes. The photocatalytic activities of the Ag species/TiO2 materials obtained were evaluated by testing the photodegradation of the azo dye reactive brilliant X-3B (X-3B) under near UV irradiation. Interestingly, it was found that the maximum photocatalytic efficiency was observed when Ag species coexisted in three valence states (Ag+, Ag2+, Ag-0 NCs), which was higher than that of Degussa P25. The high photocatalytic activity of the Ag species/TiO2 can be attributed to the synergy effect of the three Ag species. (C) 2011 Elsevier B.V. All rights reserved.