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

Abstract

Visible‐light‐driven plasmonic photocatalyst Ag‐TiO 2 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 ⋅OH radicals on the surface of visible‐light illuminated TiO 2 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 TiO 2 hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO 2 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 TiO 2 and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO 2 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.