Catalytic performance of TiO2@Ag composites prepared by modified photodeposition method

• We have successfully synthesized monodispersed TiO2 spherical colloids.
• We developed modified photo-deposition route to prepare TiO2@Ag composites.
• The method is an effective means to enable uniform distribution of Ag NPs over TiO2.
• The TiO2@Ag composites show higher catalytic activity for 4-nitrophenol reduction.

In this work, monodispersed TiO2 spheres with diameter of about 360 nm were prepared by an acetic acid assisted sol–gel method. Core–shell structure TiO2@Ag composites, constructed by the anatase TiO2 sphere cores and Ag nanoparticles (NPs) shell, were obtained via Ag nanoseed mediated photochemical reduction (modified photo-deposition) and characterized using transmission electron microscopy, XRD, X-ray photoelectron spectroscope and UV–vis spectroscopy. The characterization results indicate that Ag NPs with an average size of about 10 nm are uniformly distributed on the surface of the Ag nanoseed modified TiO2 spheres under UV radiation. For the purpose of comparison, the TiO2/Ag composites were also prepared by conventional photodeposition method and characterized. The catalytic performance of the as-prepared composites through different photo-deposited methods was evaluated by catalysis reduction of 4-nitrophenol. The results indicated that the catalytic efficiency of TiO2@Ag core–shell structures is higher than that of TiO2/Ag composites. This could be because TiO2@Ag composites have a more homogeneous distribution of Ag NPs on the TiO2 surface as well as a better contact between the Ag NPs and TiO2 than TiO2/Ag composites.

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