Effect of the spherical silica surface on the photoluminescence of the loaded US nanoparticles

CdS nanoparticles were formed on the surface of silica microspheres by the improved layer-by-layer self-assembled technique. High-resolution electron microscope (HRTEM) image and energy dispersive x-ray analysis (EDX) confirmed formation of a quasi-continuous CdS nanoparticles film on the silica microspheres. The results of UV-vis and fluorescence spectra display that the spherical silica surface has a great effect on the photoluminescence of the loaded CdS nanoparticles. In contrast to the CdS nanoparticles powder, the composite can exhibit the emission ascribed to the band gap transition when the CdS nanoparticles film is relatively thick. This phenomenon is probably due to an enhancement of the crystallinity of CdS nanoparticles induced by the silica spheres.