Silica–silver nanostructured spheres prepared by spray pyrolysis of sol containing silver precursor

Silver–silica nanostructured composites were prepared by spray pyrolysis of aqueous sols of silica nanoparticles containing silver nitrate. The physical and chemical characteristics of the composites prepared at different Ag/Si atomic ratio in the sols and temperatures of pyrolysis were examined by TEM, SEM, XRD, FT-IR and UV-visible spectra. For the low silver ratios up to 0.2, well-dispersed silver particles were produced in the pore of the silica agglomerates with their size and surface plasmon resonance depending on the pore size and silver mobility, in addition to the loading and temperature. The formation of silver silicate and new-phase silica as well as crystallinity of the silver prepared was discussed. There was also explained how the temperature of preparation affected the morphologies of the composites produced with higher Ag/Si ratios greater than 1. Mechanism on the formation of silver–silica composites was proposed for the wide range of the ratios from 0.01 to 3.