Synthesis of silver nanoparticles supported on silica aerogel using gamma radiolysis

Silver clusters on SiO2 support have been synthesized using 60Co gamma radiation. The irradiation of Ag+ in aqueous suspension of SiO2 in the presence of 0.2 mol dm−3 isopropanol resulted in the formation of yellow suspension. The absorption spectrum showed a band at 408 nm corresponding to typical characteristic surface plasmon resonance of Ag nanoparticles. The effect of Ag+ concentration on the formation of Ag cluster indicated that the size of Ag clusters vary with Ag+ concentration, which was varied from 4×10−4 to 5×10−3 mol dm−3. The results showed that Ag clusters are stable in the pH range of 2–9 and start agglomerating in the alkaline region at pH above 9. The effect of radiation dose rate and ratio of Ag+/SiO2 on the formation of Ag clusters have also been investigated. The prepared clusters have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which showed the particle size of Ag clusters to be in the range of 10–20 nm.