Microwave-Hydrothermal Preparation and Visible-Light Photoactivity of Plasmonic Photocatalyst Ag-TiO2 Nanocomposite Hollow Spheres

Visible-light-driven plasmonic photocatalyst nanocomposite hollow spheres are prepared by a template-free chemically-induced self-transformation strategy under microwave-hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy. X-ray diffraction, N-2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy. UV/Vis and Raman spectroscopy. Production of center dot OH radicals on the surface of visible-light illuminated TiO2 was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as-prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible-light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO2 hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag-TiO2 nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible-light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO2 and commercial Degussa P25 (P25) powders. Especially, the as-prepared Ag-TiO2 nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium (R) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2.