Abstract: Monolithic mesoporous silica was prepared by sol-gel technique and the CdS/SiO₂ assembly systems with different CdS loading were obtained by
immersing followed by drying and thermal reaction. The effects of annealing temperature, ambiencent and loading on the optical absorption of
CdS/SiO₂ were investigated. It is found that the optical absorption edges of the CdS nanoparticles in mesoporous silica shift to the red
as CdS loading concentration increases. The optical absorption edges red-shift along with the increase of annealing temperature under nitrogen
and blue-shift under air were observed, which can be attributed to the quantum size effect.

Key words: CdS nanoparticles, mesoporous assembly, optical absorption