Synthesis and characterization of cubic Ag/TiO2 nanocomposites for the photocatalytic degradation of methyl orange in aqueous solutions

Using a hydrothermal strategy combined with photoreduction process, Ag/TiO2 nanocomposites in which ultrasmall metallic Ag anchored on nano-TiO2 were synthesized. The SEM, TEM, EDS, XRD, as well as UV-Vis-NIR spectrum were used to characterize the Ag/TiO2 nanocomposites. It can be drawn the conclusion that the TiO2 exhibited irregular cube with a diameter of 20-30 nm, and metallic Ag anchored on the surface of nano-TiO2. The addition of metallic Ag successfully broaden the photoresponse range from UV region to visible light region. Photocatalytic activity of Ag/TiO2 was evaluated by degradation of methyl orange in aqueous solution. The results showed that the degradation rate of methyl orange by Ag/TiO2 reached 65.4% in 120 min, indicating a higher photocatalytic activity of Ag/TiO2 than that of pure TiO2 nanomaterials. The additional absorption of Ag/TiO2 in visible region was attributed to the plasmonic absorption of Ag. Moreover, the kinetic behavior could be described in terms of Langmuir-Hinshelwood pseudo-first-order kinetic equation.