A white light-emitting diode (0.33, 0.33) is fabricated using perovskite quantum dot/silica composites. It is shown to have greatly improved stability.

Efficient and Stable White LEDs with Silica-Coated Inorganic Perovskite Quantum Dots

Microwave-assisted preparation of inorganic nanostructures in liquid phase.

Colloidal heterostructured nanocrystals: Synthesis and growth mechanisms

A new, highly sensitive and uniform three-dimensional (3D) hybrid surface-enhanced Raman scattering (SERS) substrate has been achieved via simultaneously assembling small Ag nanoparticles (Ag-NPs) and large Ag spheres onto the side surface and the top ends of large-scale vertically aligned cone-shaped ZnO nanorods (ZnO-NRs), respectively. This 3D hybrid substrate manifests high SERS sensitivity to rhodamine and a detection limit as low as 10−11 M to polychlorinated biphenyl (PCB) 77—a kind of persistent organic pollutants as global environmental hazard. Three kinds of inter-Ag-NP gaps in 3D geometry create a huge number of SERS “hot spots” that mainly contribute to the high SERS sensitivity. Moreover, the supporting chemical enhancement effect of ZnO-NRs and the better enrichment effect ascribed to the large surface area of the substrate also help to achieve a lower detection limit. The arrays of cone-shaped ZnO-NRs decorated with Ag-NPs on their side surface and large Ag spheres on the top ends have potentials in SERS-based rapid detection of trace PCBs.

Arrays of Cone‐Shaped ZnO Nanorods Decorated with Ag Nanoparticles as 3D Surface‐Enhanced Raman Scattering Substrates for Rapid Detection of Trace Polychlorinated Biphenyls

Semiconductor quantum dots (QDs) exhibit unique optical and photophysical properties that offer significant advantages over organic dyes as optical labels for chemo/bio-sensing. This review addresses the methods for metal ion detection with QDs, including photoluminescent, electrochemiluminescent, photoelectrochemical, and electrochemical approaches. The main mechanisms of direct interaction between QDs and metal ions which lead to photoluminescence being either off or on, are discussed in detail. These direct interactions provide great opportunities for developing simple yet effect metal ion probes. Different methods to design the chemically-modified QD hybrid structures through anchoring metal ion-specific groups onto the surface of QDs are summarized. Due to the spatial separation of the luminescence center and analyte recognition sites, these chemically-modified QDs offer greatly improved sensitivity and selectivity for metal ions. Several interesting applications of QD-based metal ion probes are presented, with specific emphasis on cellular probes, coding probes and sensing with logic gate operations.

Semicondutor quantum dots-based metal ion probes

This manuscript describes the low-temperature, solution-based doping of Mn2+ ions into colloidal ZnO nanorods, and the yield of the products is in a gram scale. The structures and chemical compositions of the products were characterized by XRD, XPS, EDS, and FT-IR spectroscopy. The results demonstrate that Mn2+ ions were successfully incorporated into the lattice position of Zn2+ ions in ZnO. The concentration of Mn2+ ions (in molar %) in the products can be controlled in the range of 1.25∼5%. The surfaces of Mn-doped ZnO nanocrystals have very rich hydroxyl groups, which enhance their solubility in many polar and nonpolar solvents. TEM and FESEM were used to characterize the morphology of ZnO and Mn-doped ZnO nanocrystals, and they revealed that both the undoped and doped ZnO nanocrystals are composed of uniform nanorods with a diameter of 8 nm and a length of 95 nm. The doping of Mn2+ ions has significant influences on the optical properties of ZnO nanorods. UV−vis absorption spectroscopy measurements r...

http://www.dstuns.iitm.ac.in/grouppresentations/2009/Solution-Based%20Doping%20of%20Manganese%20into%20Colloidal%20ZnO%20Nanorods.pdf

Solution-Based Doping of Manganese into Colloidal ZnO Nanorods

In this paper, we demonstrated the encapsulation of CdTe quantum dots (QDs) and ZnO nanorods (NRs) with a layer of mesoporous SiO2 shell (pore size: 4.1 nm) for the purpose of integrating dual-emission property into one common nanostructure. Within the core−shell CdTe/ZnO@SiO2 nanocomposites, CdTe QDs and ZnO NRs provide visible emission and UV emission, respectively. The fluorescence intensity ratio of the dual emission can be tuned by altering the hydrolysis time of tetraethyl orthosilicate (TEOS). The core−shell CdTe/ZnO@SiO2 nanocomposites exhibit very interesting photoluminescent behaviors after interactions with heavy-metal ions such as Hg2+, Pb2+, and Cu2+. The visible emission contributed by CdTe QDs was abnormally enhanced in a range of 20−90% at the concentration of Hg2+ < 10−8 M, Pb2+ < 10−5 M, and Cu2+ < 10−6 M, whereas the intensity of UV emission by ZnO NRs was kept constant in all cases. Consequently, the UV emission may serve as a reference. The mechanism of the fluorescence enhancement is...

Fabrication of Mesoporous CdTe/ZnO@SiO2 Core/Shell Nanostructures with Tunable Dual Emission and Ultrasensitive Fluorescence Response to Metal Ions

Facile synthesis of highly uniform ZnO multipods as the supports of Au and Ag nanoparticles

A strategy of co-reaction of Fe and TiO2 with concentrated NaOH was designed to prepare Na2Ti3O7 nanosheets grown epitaxially by Fe3O4 crystallites, for the purpose of modifying interlayer structures and ion exchange properties of the layered compound Na2Ti3O7 TiO2 could react with NaOH to form lamellar intermediates while Fe could be converted into Fe3O4 to deposit on the surface of the intermediates Eventually, free-standing Fe3O4@Na2Ti3O7 nanosheets were successfully synthesized in an extremely high yield (∼95% efficiency) Fluorescein and its derivatives utilized as probes to study the ion exchange property of Fe3O4@Na2Ti3O7 nanosheets, which could provide visual observations of the degree of ion exchange The results indicate that the as-prepared Fe3O4@Na2Ti3O7 nanosheets possess much more sensitive Na+ exchange performance than isolated Na2Ti3O7 nanostructures, and hence they should have potential application in the extraction of trace active components, such as cationic amino acid and peptides in biology Furthermore, the present strategy is also helpful in the design synthesis of other layered compounds grown epitaxially by magnetic clusters to achieve enhanced physicochemical properties

Yingying Song

Papers

Solution-Based Doping of Manganese into Colloidal ZnO Nanorods

Fabrication of Mesoporous CdTe/ZnO@SiO2 Core/Shell Nanostructures with Tunable Dual Emission and Ultrasensitive Fluorescence Response to Metal Ions

Facile synthesis of highly uniform ZnO multipods as the supports of Au and Ag nanoparticles

Ultrasensitive Na+ exchanging performance of free-standing Fe3O4@Na2Ti3O7 nanosheets indicated by fluorescein

One-pot, high-yield synthesis of titanate nanotube bundles decorated by Pd (Au) clusters for stable electrooxidation of methanol