Ag/TiO2 and Ag/SiO2 composite spheres: synthesis, characterization and antibacterial properties

Abstract

Ag/TiO₂ and Ag/SiO₂ composite spheres with core–shell structures were synthesized via an ion-exchange method. Thin layers of TiO₂ or SiO₂ are deposited onto CaMg(CO₃)₂ templates using tetrabutyl titanate or tetraethoxysilane, respectively, and the CaMg(CO₃)₂ cores are subsequently replaced by Ag₂CO₃ based on the solubility product constant gap, followed by calcination of the intermediates, resulting in Ag/TiO₂ and Ag/SiO₂ composite particles. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX). The amount of Ag nanoparticles in the composites can be adjusted using the relative concentration of the AgNO₃ solution. Both the Ag/TiO₂ and Ag/SiO₂ composites exhibit excellent antibacterial activities using E. coli and S. aureus as test bacterial spawn.