A sonochemical approach to the surface synthesis of cadmium sulfide nanoparticles on submicron silica

Abstract

A sonochemical procedure for the preparation of cadmium sulfide (CdS) nanoparticles coated on submicron spherical silica particles has been described. Ultrasonic irradiation of a slurry of silica microspheres, cadmium sulfate, and thiourea in an aqueous medium for 3 h under ambient air yields cadmium sulfide–silica (CSS) composite. Heating the initial amorphous CSS nanocomposite at 150 °C for 1 h under a N2 atmosphere yields diffraction peaks assignable to the CdS phase. The transmission electron microscopy image of CSS shows that the CdS nanoparticles homogeneously coated on the silica (SiO2) carrier. The infrared spectroscopy illustrated the structural changes that occur when the amorphous SiO2 is coated with CdS nanoparticles ultrasonically. The photoluminescence spectrum of the CdS and CSS shows a broadband with a maximum centered around 560 nm, which is similar to that of quantum CdS particles. The sharp onset of a CSS emission band compared to that of the CdS emission band in the red region indicates that the SiO2 carrier provides a medium for controlling the aggregation of CdS nanoparticles.