Microwave-assisted Synthesis Of Lead Sulfide Nanomaterials And Their Applications

Because of their excellent performance in optics, electronic or thermoelectric field, a great deal of attention has been attracted to PbS nanomaterials. However, how to control the dimension and morphology of lead sulfide micro-nano structures is still one of the key challenges the current materials and nano technology are facing. In this paper, we created a new route to synthesize self-assembled macro rod of PbS, and also synthesized Te doped PbS heterogeneous nanomaterials by using microwave heating and ultrasonic assisted liquid phase reaction. Raman spectrum of the self-assembled PbS rod and applications of Te doped PbS heterostructures in the thermoelectric field were investigated. More specific contributions are listed as follows:1. A microwave- ultrasonic method of decomposing Pb(DMDC)2 in liquid phase was developed. It leads to the formation of high quality self-assembled Pb(DMDC)2/PbS QDs macro rod, which then transformed into others microstructures such as hexapod-like PbS. By studying the influence of reaction temperature on the morphology, size and product structures of Pb S products, it was observed that the formation of Pb(DMDC) 2 / Pb S QDs self-assembled microns rods dominants at low temperature, whereas at high temperature hexapod-like PbS nanocrystals are the major products.2. Raman spectra of the PbS products were investigated at room temperature and results show that the products are sensitive to the laser illumination and can be photodegraded easily. Over a broad temperature range, the intensity of the Raman spectrum decreases with the increase of the measuring temperature. For example, Raman spectrum decreases and the linewidth gradually broadens from 1000cm-1 to 1600cm-1 and2600cm-1to 3000cm-1. The PbS rod products were studied for possible SERS applications, the results show that the sample exhibits large3. enhancement for 4-Mercaptopyridine signal. Comparing with4-Mercaptopyridine power、Au nanoparticles and PbS QDs,the results show that signal at the rod is much higher than that on the powder and PbS QDs, and nearly the same as using Au nanoparticle substrates.4. High quality Te doped Pb S heterogeneous nanomaterials with a novel dumb-bell appearance were synthesized with the same microwave heating ultrasonic assisted reflux method using glycol as the solvent.Thermal electric properties of the dumb-bell shaped Te-PbS products were investigated, which shows the highly improved Seebeck coefficient,indicating that the products have attractive thermoelectric properties.