Synthesis and photoluminescent properties of ZnS:Cd nanoparticles and their phase-transferred nanocomposite with polyvinylpyrrolidone

Abstract

ZnS:Cd nanoparticles were synthesized in a reverse micelle system by controlling reaction factors with mercaptoacetic acid (MPA) as a surfactant and N,N-dimethylformamide as an oil phase. X-ray diffraction pattern shows that the ZnS:Cd nanoparticles exhibit a cubic structure and its mean size is calculated around 4 nm. With different molar ratios of Zn²⁺/S²⁻, the relative intensity of the emission peaks at 400 and 556 nm changes dramatically due to the more sulfur vacancies which resulted from the imbalance of Zn²⁺ and S²⁺ ions. Furthermore, hydrophobic phase-transferred ZnS:Cd nanoparticles were obtained using octylamine, and a highly luminescent phase-transferred ZnS:Cd/polyvinylpyrrolidone (PVP) nanocomposite was prepared by blending the phase-transferred ZnS:Cd with PVP. Infrared absorption suggests that octylamine has been successfully connected with the MPA-coated ZnS:Cd nanoparticles. Unlike the MPA-coated ZnS:Cd which has a very strong emission at 556 nm, the phase-transferred ZnS:Cd has a strong emission at 435 nm, which is ascribed to surface passivation and electron redistribution. In addition, luminescent intensity enhancement was observed for the phase-transferred ZnS:Cd/PVP nanocomposites with various Cd²⁺ doping concentrations.

Keywords:

• ZnS:Cd
• PVP
• nanocomposite
• phase transfer
• luminescence

Acknowledgments

The authors greatly acknowledge the financial support by the National Science Foundation of China (No. 21073012, 20773012).

Additional information

Funding

The financial support by the National Science Foundation of China [grant number 21073012], [grant number 20773012].