Xiuwen Zheng

Formation of vesicle-templated CdSe hollow spheres in an ultrasound-induced anionic surfactant solution

Hollow sphere of CdSe with size of approximately 100-200 nm can be templated from anionic surfactant sodium dodecyl sulfate (SDS) vesicles induced by the ultrasonic irradiation. The successful vesicle templating indicated that the outer leaflet of the bilayer is the receptive surface in the controlled growth of CdSe nanoparticles, which provide the unique reactor for the nucleation and mineralization growth of CdSe nanoparticles. The products were characterized by XRD, TEM, and HRTEM techniques. UV-vis spectrum recorded the optical properties of CdSe hollow spheres (2.01 eV), which showed an obvious blue shift relative to the bulk cubic CdSe (1.73 eV). Surfactant molecules (SDS) passivated in the CdSe hollow spheres were completely extracted, as determined by thermal gravimetric analysis (TGA). Systematic studies found that the ultrasound irradiation and concentration of surfactant (SDS) in the system were important factors on the controlled synthesis desired hollow sphere morphologies, and also the temperance have an importance influence on the mineralization and crystallization of the CdSe hollow spheres. Based on the observation on morphological difference of CdSe in different systems, the possible mechanism for the formation of CdSe hollow spheres was discussed.

Ultrasound-assisted cracking process to prepare MoS2 nanorods.

A simple ultrasound-assisted cracking process was applied to prepare high-crystallinity MoS2 nanorods using MoS2 micron particles as raw materials. The products were characterized by various techniques, including XRD, SEM, TEM and HRTEM. Systematic studies showed that acid treatment and ultrasound irradiation are both prerequisites for the preparation of ideal MoS2 nanorods. TEM images indicate that these nanorods have uniform morphology, with an average diameter of approximately 150 nm and length up to several microm. Based on the controlled experiments and observation on morphological changes, it is proposed that the activated layered MoS2 first exfoliate into sheets and further crack into smaller nanorods due to the strong mechanical agitation, shear forces, and micro-jets created by the ultrasound irradiation.

Reduction of selenious acid induced by ultrasonic irradiation––formation of Se nanorods

Single crystalline Selenium nanorods are formed via the reduction of selenious acid induced by ultrasonic irradiation. The products were characterized by XRD, TEM and ED techniques. The possible mechanism for the formation of selenium nanorods was discussed.