Characterisation and preparation of sonochemically synthesised silver–silica nanocomposites

Properties of nanoparticles differ from those of bulk phase or individual molecules. The metal form of these particles shows chemical and physical properties that can be used in fields such as optics, opto-electronics and catalysis. Silver nanoparticles can be used as an antimicrobial agent in wound dressings and as surface coatings, e.g., catheters. In this work, silver nanoparticles were deposited on silica submi-crospheres using ultrasounds. A mixture of silver nitrate solution with silica submicrospheres was sonifi-cated under an atmosphere of argon gas in order to eliminate oxygen and decrease both the cavitational threshold as well as the intensity of the ultrasounds. Duration of irradiation was varied between 90 and 180 min at a the frequency of 24 kHz.The resulting silver–silica nanocomposites were characterized with Fourier transform infrared (FTIR), high resolution transmission electron microscopy (HR-TEM), scan-ning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and X-ray florescence (XRF). The results of SEM micrographs show submicrospheres of silver-silica nanocomposites, with the 16–64 nm size distribution. Furthermore, HR-TEM micrographs show that the particle size distribution does not depend on time of irradiation. The particle size distribution of silver nanocomposite in all sam-ples was approximately 4–30 nm. EDAX and FTIR measurements show that, with increasing AgNO3 concentration, the percentage of deposited silver on silica increases. XRF patterns show that the amount of silver deposited on silica can be increased by increasing the ultrasound power. Key words: energy dispersive X-ray analysis; high resolution transmission electron microscopy (HR-TEM); scanning electron microscopy; silver nanocomposite; sonochemical treatment 1