CdS@SiO2 nanoparticles synthesized from polyoxyethylene (10) tertoctylphenyl ether based reverse microemulsion

CdS–Silica core–shell (assigned as CdS@SiO2) nanoparticles have been synthesized by directly covering silica on the CdS nanocrystalline surface in the same reverse microemulsion composed of polyoxyethylene (10) tertoctylphenyl ether (Triton X-100)/1-hexanol/cyclohexane/H2O. The influencing factors, such as the volume ratio of CdCl2 aqueous solution, ethanol solution containing thioacetamide (TAA), ammonia and tetraethyl orthosilicate (TEOS) were investigated in detail. The transmission electron microscopy (TEM) images showed CdS nanocrystalline aggregated in the silica interior, and the spherical uniformity and regularity of CdS@SiO2 nanoparticles varied along with the variation of reactants. The X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) proved both uncovered CdS nanocrystallines and CdS@SiO2 nanoparticles have zinc blend structures. The UV–vis absorption and photoluminescence (PL) spectra demonstrated the quantum confinement effect and the spectral change of the CdS nanocrystalline after covered by silica. A mechanism of the formation of CdS@SiO2 nanoparticle was proposed based on the analysis of low- and high-resolution electron microscopy (HR-TEM) results.