High yield synthesis of matchstick-like PbS nanocrystals using mesoporous organosilica as template.

A simple hard template method has been developed to prepare uniform matchstick-like PbS nanocrystals. The approach combines functionalization of the mesoporous walls and channel surface with thioether groups, adsorption of Pb2+, and heating in an N2 atmosphere at high temperature. The structure, morphology and composition of the nanocrystals have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The optical properties of the matchstick-like PbS nanocrystals have been systematically investigated by Raman spectroscopy, UV-visible absorption spectroscopy (UV-vis), and photoluminescence spectroscopy (PL). These results demonstrate that these matchstick-like PbS nanocrystals are single crystals and possess novel optical properties, suggesting that they may have many potential applications. A large blue shift is observed in the photoluminescence spectrum, and this clearly shows the quantum size effects of the matchstick-like PbS . Furthermore, a growth mechanism of the PbS heteronanostructure is proposed.