Effects of Annealing on the Optical Absorption of CdS/SiO_2 Assembly

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.