Preparation and characterization of CdS/ZnS core-shell nanoparticles

Abstract

Cadmium sulfide/zinc sulfide (CdS/ZnS) core-shell nanoparticles in polyacrylamide (PAM) colloid particle were prepared by the succession of inverse miniemulsion polymerization and absorption. The cadmium sulfate (CdSO₄)-PAM colloid was firstly prepared by inverse miniemulsion polymerization, the CdS nanoparticles were formed by reaction between CdSO₄ in PAM particles and excessive sodium sulfide in being-absorbed miniemulsion droplets; and then the ZnS nanoparticles were orientated-grew onto CdS nanoparticles by slowly absorbing zinc acetate in miniemulsion droplets. The effects of the Cd²⁺/Zn²⁺ molar ratios on CdS/ZnS-PAM particles preparation were investigated. When the Cd²⁺/Zn²⁺molar ratio was 1:1, the Z average diameter of the CdS/ZnS-PAM particles was 178 nm. The CdS/ZnS crystals showed a greater size with Zn²⁺ mole fraction increase. The core-shell structure of CdS/ZnS nanoparticles was confirmed successfully by transmission electron microscopy observation, X-ray diffraction analysis and so on. The ZnS shell layer played an important role in modification and reduced the surface defects of nanocrystals effectively. The succession method will provide a great advantage in core-shell structure CdS/ZnS preparation.

Graphical Abstract

Keywords:

• Inverse miniemulsion
• cadmium sulfide
• zinc sulfide
• core-shell
• polyacrylamide