Optical Properties of Zinc Sulfide Nanopowders and ZnS/Ag2S Heteronanostructures

Abstract

Nanopowders of zinc sulfide (ZnS) and ZnS/Ag2S heteronanostructures were synthesized by chemical deposition from aqueous solutions. A change in the ratio between the concentrations of reagents allowed us to obtain ZnS nanopowders with a particle mean size from 2 to 10 nm. The Ag2S nanoparticle size in the resulting heteronanostructures was 9–30 nm and the ZnS surface layer thickness was equal to 4–5 nm. The diffuse reflectance spectra for nanostructured ZnS and ZnS/Ag2S heteronanostructures were measured. Based on the analysis of the obtained spectra, the bandgap energy Eg in the studied sulfide nanostructures was estimated. Upon a decrease in the nanoparticle size from 10 to 2 nm, the Eg value in ZnS nanopowders increased in a range of 3.17–3.36 eV. An increase in the content of Ag2S in the ZnS/Ag2S heteronanostructures led to a decrease in the bandgap energy and a decrease in the luminescence intensity.