Qianyu Liu

Effects of surface modification and SiO2 thickness on the optical and superparamagnetic properties of the water-soluble ZnS:Mn2+ nanowires/Fe3O4 quantum dots/SiO2 heterostructures

In this paper, one-dimensional ZnS:Mn2+ nanowires (NWs)/Fe3O4 quantum dots (QDs)/SiO2 heterostructures were successfully synthesized by the Stober method to form the water-soluble fluorescent/superparamagnetic nanocomposites. The average diameter of the ZnS:Mn2+ NWs, Fe3O4 QDs and ZnS:Mn2+ NWs/Fe3O4 QDs/SiO2 heterostructures was about 6–8 nm, 4–5 nm and 18 nm, respectively. The Fe3O4 QDs were covalently linked to the ZnS:Mn2+ NWs by the conjugation of the hydroxyl groups on the surface of the QDs and the carboxyl groups modified on the surface of the NWs. It was found that the covalent bonds between the NWs and QDs could effectively suppress the energy transfer from the ZnS:Mn2+ NWs to the Fe3O4 QDs. As the SiO2 shell thickness increased, the fluorescence intensity reached the highest value when the hydrolysis time of tetraethyl orthosilicate was 5 hours, which was comparable to that of the ZnS:Mn2+ NWs. The superparamagnetic properties of the heterostructures were observed at room temperature, which decreased as the SiO2 thickness increased.

One-step hydrothermal synthesis of shape-controlled ZnS–graphene oxide nanocomposites

Abstract Shape-controlled ZnS–graphene oxide (GO) nanocomposites were successfully synthesized via an easy one-step hydrothermal method by changing the solvents. The sample prepared in ethytleneglycol and water (1:1 in volume ratio) yielded ZnS nanoparticles (NPs)–GO nanocomposites. The sample prepared in ethylenediamine and water (1:1 in volume ratio) yielded ZnS nanowires (NWs)–GO nanocomposites. The sample prepared in ethytleneglycol, ethylenediamine and water (1:1:2 in volume ratio) yielded ZnS nanorods (NRs)–GO nanocomposites. The results showed that the GO in the composite were exfoliated and decorated with ZnS NPs, NWs and NRs. The photoluminescence intensity of the ZnS–GO nanocomposites exhibited a clearly quenching in comparison with that of ZnS.