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

• Ag-deposited SiO2 core/TiO2 shell composite sphere with uniform shape and size.
• Ag–SiO2@TiO2 sphere exhibits much enhanced photocatalytic activity than SiO2@TiO2.
• The reported SiO2@TiO2 has been a nanocomposite with aggregated nanoparticles.
• Ag–SiO2/TiO2 sphere with a submicrometer size successfully degraded the AB 1 dye.
• Ag–SiO2/TiO2 composite sphere photocatalyst is stable and reusable.

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.

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