Dernière modification: 2017-10-02
Résumé
Nanostructured materials may be defined as materials whose structural elements - clusters, crystallites or molecules- have dimensions in the 1 to 100 nm range. As compared to bulk materials, nanoscale materials exhibit large surface areas and size-dependent quantum confinement effects. They often have distinct electronic, optical, magnetic, chemical, and thermal properties
One of the important goals for nanoscale synthesis is the production of structures that achieved monodispersity, stability, and crystallinity with predictable morphology. Nowadays, the solution-phase approach has become a promising technique to prepare nanostructures. During the solution-phase synthesis of nanoparticles, the control of nucleation and successive growth, which is extremely sensitive to the synthetic parameters, has been believed to be the key to the size and shape-controlled synthesis of nanostructures.
In principle we can classify the wet chemical synthesis of nanomaterials into two broad groups:
The top down method: where single crystals are etched in an aqueous solution for producing nanomaterials.
The bottom up method: consisting of precipitation method, sol-gel etc. where materials containing the desired precursors are mixed in a controlled fashion to form a colloidal solution.
The current work is devoted to the synthesis of nanostructured CuO, Cu2O, ZnO and Silicon (nanoparticles and nanosheets) with high specific surface area using a fast, facile and inexpensive solution method which should be suitable for large-scale production.
Bottom up method was applied to prepare nanostructured CuO, Cu2O and ZnO powders at room temperature from metallic copper powder, zinc powder, and other precursors in the presence of directing agent such as ethylene glycol, sodium dodecyl Sulphate (SDS)...
Using top-down solution processes,one pot synthesis of silicon nanoparticule and silicon sheets in gram-scale quantities by Redox-Assisted Chemical Exfoliation (RACE) of calcium disilicide (CaSi2) from materials including a 2D sheet structure as a fundamental unit was reported. Among many Zintlsilicides, only calcium disilicide (CaSi2) has a structure that includes 2D silicon puckered sheets in which the Si6 rings are interconnected. The puckered (Si"’)npolyanion layers are separated from each other by planar monolayers of Ca2+.
All the prepared nanoparticles were characterized by X-ray diffraction measurements (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), scanning electronmicroscopy (SEM) and Nitrogen adsorption (BET).