Shiyun Lou

Synthesis and assembly of monodisperse spherical Cu2S nanocrystals.

High-quality monodisperse Cu(2)S nanocrystals (sizes from 2 nm to 20 nm) have been successfully synthesized by the reaction of copper stearate (CuSt(2)) and dodecanethiol (DDT) in 1-octadecene (ODE). The nanocrystals were characterized using X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), and transmission electron microscopy (TEM). These as-prepared Cu(2)S nanocrystals with certain sizes have been found with good self-assembly behaviors, and they were easily to assemble into two-dimensional and three-dimensional superlattice structures. DDT served as both sulfur source and capping ligand, and was found a key factor to affect the growth and the self-assembly behaviors of the Cu(2)S nanocrystals.

Controlled synthesis of different types iron oxides nanocrystals in paraffin oil

Monodisperse Fe3O4 and FeO nanocrystals (NCs) with different sizes (from 10 nm to 50 nm) and different shapes (cube, sphere, and ellipsoid) were synthesized by simply adjusting reaction temperature or molar ratio of Fe/oleic acid (OA) during the decomposition of FeO(OH) in noncoordinating solvent. The concentration of OA affected the nucleation and growth of NCs by improving the chemical reaction driving force during the syntheses of different types of iron oxide NCs. It has been found that the reaction temperature influenced the reaction activity between FeO(OH) and OA. The structure of Fe oleate complexes was studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM) were used for structural and chemical characterization of as-prepared iron oxide NCs.

Controlled synthesis of monodisperse manganese oxide nanocrystals

Monodisperse manganese oxide nanocrystals (NCs) have been successfully synthesized through the decomposition of Mn(acac)2 in nonpolar solvent. By simply adjusting the nucleation temperature, NCs with Mn3O4 or MnO structures were synthesized in sizes ranging from 5 to 25 nm. To obtain monodisperse NCs, the growth temperature was set at 30 °C lower than the nucleation temperature by injecting paraffin oil. It has been demonstrated that every ligand (including oleic acid, oleylamine, and dodecanol) played an important role during the synthesis process. The structure and shape properties of manganese oxide NCs synthesized with different ligands have been studied and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and transmission electron microscopy (TEM).

Controlled synthesis of high quality type-II/type-I CdS/ZnSe/ZnS core/shell1/shell2 nanocrystals.

Using phosphine-free and green chalcogen precursors, controlled synthesis of high quality CdS/ZnSe/ZnS core/shell1/shell2 nanocrystals has been successfully carried out using different sized CdS nanocrystals as cores. The properties and structures of the synthesized nanocrystals were characterized by absorption spectroscopy, photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and inductively coupled plasma mass spectroscopy (ICP-MS). By changing CdS core sizes and/or ZnSe shell thicknesses, the PL range of CdS/ZnSe core/shell nanocrystals could be adjusted from 500 nm to 630 nm with type-II optical characteristics. The PL quantum yields (QYs) of these nanocrystals were 50-60% after the growth of thick ZnS shells, their full width at half maximum (FWHM) was kept below 50 nm during the entire growth process, and the total Cd content was reduced to about 1% in atomic ratio. TEM images showed narrow size distributions and XRD results demonstrated the zinc blende structure of CdS was retained following subsequent growth of ZnSe and ZnS shells. More than 2 g of high quality CdS/ZnSe/ZnS nanocrystals were successfully prepared in a large scale synthesis with the use of only low-cost, green, and environmentally friendly reagents.

Investigation on the phosphine-free synthesis of CdSe nanocrystals by cadmium precursor injection

A green route for the synthesis of high quality zinc blende CdSe nanocrystals has been successfully established by using phosphine-free Se precursors combined with a cadmium precursor injection method. The effects of using different Se precursors, and adjustment of the molar ratios between the Cd and Se precursors have been investigated in detail to optimize the synthesis conditions. Absorption and photoluminescence (PL) spectra, X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used for the characterization of synthesized CdSe nanocrystals. High brightness with the photoluminescence quantum yields up to 50% and narrow size-distribution with the full width at half-maximum (FWHM) below 24 nm were obtained under the optimized conditions. More than 5 g of high quality CdSe nanocrystals have been synthesized in one large scale reaction.