Facile synthesis of heterostructured Ag-deposited SiO2@TiO2 composite spheres with enhanced catalytic activity towards the photodegradation of AB 1 dye

Ternary Ag-SiO2@TiO2 heterostructured composite spheres were synthesized and investigated as a catalyst for the photodegradation of Acid Black 1 (AB 1) in an aqueous solution. The SiO2 spheres (310 nm) and SiO2@TiO2 composite spheres (320 nm) were prepared without aggregation by the sol-gel method using tetraethyl orthosilicate (TEOS) and Ti(iBuO)(4) as precursors. Different concentrations of Ag nanoparticles were photodeposited on SiO2@TiO2 spheres with particle sizes of about 10 nm. The Ag nanoparticles on the SiO2@TiO2 composite spheres (Ag-SiO2@TiO2) were extensively characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning microscopy (FE-SEM), transmission electron microscopy (TEM), UV-diffuse reflectance spectroscopy, and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the Ag-SiO2@TiO2 photocatalyst towards AB 1 under UV irradiation was studied. The effects of the operational parameters such as the different Ag contents on the SiO2@TiO2 composite spheres, as well as the effect of the initial concentration of the dye solution on photomineralization were analyzed. The results showed the Ag-SiO2@TiO2 photocatalyst to be efficient and reusable. (C) 2014 Elsevier B.V. All rights reserved.