Synthesis And Reversible Phase Transfer Of Water-soluble CdS Nanoribbons

CdS is one of the most important II-VI semiconductor compound, of which thebandgap is2.4eV at room temperature （300K）. In recent years, the preparation andapplication of CdS nanoribbons （NRs） has become the focus of research. However,CdS NRs usually should be dispersed in different solvents before application. In thispaper, water-soluble CdS NRs with well-defined morphology and excellentfluorescence properties were directly synthetized in aqueous phase. HyperbranchedCdS nanobundles （NBs） could be obtained if CdS NRs were under UV irradiation inthe self-assembly progress. It is important that reversible phase transfer ofwater-soluble CdS NRs between water phase and organic phase could be achieved byusing d ifferent transfer agents. If CdS NRs were under UV irradiation in the phasetransfer progress, we could obtain nanospirals （NPs） with similar structure to DNA,which has a double helix structure.The study showed that: water-soluble CdS NRs were assembled from CdSnanoparticles obtained by the slow oxidation of Te^2-in the initial CdTe. If CdS NRswere under UV irradiation in the self-assembly progress, photooxidation and twistingof CdS NRs would happen, thus, forming hyperbranched CdS NBs. In the phasetransfer progress, CTAB moleculars would be absorbed onto the surface of CdS NRsdue to electrostatic interaction. CdS NRs with long alkyl chains stretched out wouldbe oil-soluble. The anionic CdS NRs were less hydrophobic per unit charge than thedecanoate anion. Hence, the hydrophobic （CTA）+D-partitioned into chloroform.Thenthe CdS NRs could be re-dispersed in water. Photooxidation and twisting of CdS NRswould happen if oil-soluble CdS NRs were under UV irradiation in the phase transferprogress, thus, forming NPs via reversible transfer to water. Photo-switch testsshowed that oil-soluble CdS NRs could be homogeneously mixed with P3HT, whichwas benefit to effective separation of excitons and rapid transfer of carriers. Thisresult suggested that oil-soluble CdS NRs could find potential applications inphotoelectric conversion devices.