A series of Ag-doped titania nanocrystallites were prepared by the microwave treatment. It was found that the microwave-treated Ag-doped plays synergistic effect on the phase transformation and the photocatalytic activity of titania nanocrystallite. The pure titania nanocrystallites and the silver-doped titania nanocrystallites were analyzed by X-ray diffraction (XRD), transmission eletron microscope (TEM), X-ray photoelectron spectrophotometer (XPS), Raman spectroscopy and diffuse reflectance spectrophotometer (DRS) to determine their physicochemical characteristics. The results showed that the Ag-doped titania nanocrystallite with an average diameter of 10 nm contained anatase as the main phase and rutile phase. Itwas found that the Ag dopant promoted the formation of the rutile phase, reduction the size crystallite of titania nanocrystallite, and the photoresponse of titania nanocrystallite was red-shifted about 6 nm to the visible region. For the doped Ag, the species of Ag0/Ag+ were found on the surface of titania nanocrystallite in a highly dispersed state, within a relative low concentration range. The Ag-doped titania nanocrystallites can effectively capture the photoinduced elctrons and holes, resulting in drastic enhancement of the photocatalytic activity, which was evaluated by measuring the decomposition rates of Rhodamine B exposed to the near ultraviolet-visible light radiation. For the Ag-doped titania nanocrystallite, the highest degradation ratio was observbed with the Ag content of 0.05 mol %.

Key words: nano-titania, Ag dopant, microwave, phase transformation, photocatalytic activity