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

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.