Search

Multicomponent nanocomposite colloidal spheres were synthesized with NaYF 4 :Yb,Er upconversion nanoparticle and CdSe quantum dots for tailoring visible emission. The CdSe/NaYF 4 :Yb,Er colloidal spheres were synthesized by improved emulsion-based self-assembly approach. They are well-dispersed in the colloidal sphere by electron diffraction X-ray mapping patterns. The colloidal spheres exhibited near-infrared photoresponse property. The intensity of short-wavelength emission at 408 nm was drastically weakened, and a red emission at 655 nm is substantially increased. Both the mechanism and multi-photon process of upconversion photoresponse was determined. It offers facile strategy to assemble multicomponent nanocomposite colloidal spheres for tuning visible emission. The multicomponent nanocomposite CdSe/NaYF 4 :Yb,Er colloidal spheres were constructed and its visible emission was tuned under near-infrared excitation. Unlabelled Image [ABSTRACT FROM AUTHOR]

Highly monodispersed core-shell structured NaGdF 4 :Yb,Er@SiO 2 @Eu(TTA) 3 Phen(2-Thenoyltrifluoroacetone (TTA), 1,10-Phenanthroline monohydrate (Phen)) nanospheres were synthesized via two-step process. These nanospheres with diameter of 13 nm were encapsulated in SiO 2 shell via micro-emulsion preparation. The ligand-sensitized Eu complexes attached to the outer surface of SiO 2 . The green (542 nm) and red (610 nm) light were excited by NIR and UV illumination, respectively. Thus, tunable photoresponse was possible in the core-shell structured hybrid nanocomposites. Under upconversion process, 5-fold increase at 542 nm and a 14-fold increase at 660 nm could be achieved under 980 nm laser, respectively. [ABSTRACT FROM AUTHOR]

Inorganic-organic nanocomposites are synthesized and applied in polymer solar cells (PSCs) for improving power conversion efficiency (PEC). The hexagonal NaYbF 4 :Tb/Eu nanocrystals are synthesized, and then two organic molecules, phenanthroline (Phen) and thenoyltrifluroacetone (TTA), are introduced to modify the surface of the NaYbF 4 :Tb/Eu. As organic antennas, Phen and TTA can absorb UV and then transfer energy to inorganic nanocrystals. The prepared nanocomposites combine upconversion (UC) and downshift (DS) process under excitation, which can convert them into visible light. Thus, the inorganic-organic nanocomposites display photoresponse both in UV and NIR region. Two organic ligands and Tb 3+ play an indispensable role during the energy transfer process. The enhanced UC and tunable DS emission match well with absorption of active layer of PSC, which can enhance the performance of PSC. The open-circuit voltage (V oc ) and short-circuit current density (J sc ) of the devices are about 0.77 V and 16.48 mA cm −2 , respectively. And the PEC of PSC can be increased 7.85%, which is about 10.2% higher than that of the reference device without UC and DS. [ABSTRACT FROM AUTHOR]

The well-defined lanthanide co-doped upconversion nanoparticles(UCNPs) had been synthesized using a simple solvothermal route at 150 °C, which was lower than previous reports. The shuttle-like and spherical UCNPs co-doped by Yb 3+ /Tm 3+ had been prepared, respectively. The morphology, crystal phase and size distribution of various UCNPs could be easily controlled. The growth mechanism and morphology transition of UCNPs had been deduced by schematic diagram. UC luminescence could be tuned by employing different host lattices (GdF 3 , YF 3 , NaGdF 4 and NaYF 4 ). NaGdF 4 :Yb 3+ /Tm 3+ displayed the strongest UC luminescence at 475 nm among four kinds of UCNPs, and its emission intensity was almost 10 times higher than that of NaYF 4 :Yb 3+ /Tm 3+ . UC mechanism had been determined by energy level diagrams. It’s revealed that the accumulation and energy transfer of Gd 3+ could be demonstrated in polycrystalline structure. The work provided a simple method for preparation of UCNPs with tunable UC luminescence. [ABSTRACT FROM AUTHOR]

The structure of biomimetic approach to converting sunlight was applied for design of composite materials. Here, hierarchical tree-like heterostructure Ag/ZnO (Ag wt%: 8.9%) arrays were fabricated by two-step electrodeposition, and it exhibited improved activity during photoelectrochemical water oxidation. The wurtzite-structured ZnO arrays prepared are the "trunk". Ag nanoclusters were selectively deposited on the top of arrays as the "leaf", which can strongly interact with visible light due to surface plasmon resonance. The inducted electromagnetic fields around Ag would efficiently propagate energy to composites by hot electrons injection. Based on morphology and crystal structure analysis, the linear sweep voltammagrams display that photocurrent increase to 0.17mA/cm2 at 1.23 VRHE, and the photo-to-hydrogen generation is 0.23%. Additionally, the amperometric I-t curves collected without voltage displayed better photocurrent response under sunlight. The kinetics of PEC process at the electrode surface was investigated by electrochemical impedance spectroscopy (EIS). The mechanism was deduced based on the energy level of ZnO and Ag. The designed plasmonic crystal system exhibited that tree-like heterostructure is favorable for improving sunlight absorption and photoeletrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract: Compared to conventional methods, a simple route is offered for synthesis of BaCO3 with CO2 and least energy consumption. And the morphology of BaCO3 was tuned by controlling reaction conditions. The X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) were employed to characterize the products, the results showed that the products with various morphologies had the same crystal phase and growth direction. However, the distinct difference of the prepared products were determined by Raman and UV–vis spectra, showing shape-dependent optical properties. The results provide a useful model system for investigating the shape-dependent optical properties of carbonate nanocrystals. [Copyright &y& Elsevier]

Abstract: The nanostructured ZnS of cubic nanocorals and open-benzene ring has been synthesized by the biomolecule-assisted method in mixture of supercritical carbon dioxide and water as reaction medium at 150°C and 28MPa. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence spectrum of sample were characterized. The sodium tripoly phosphate and CO2 as well as high-pressure condition might be the key factors for formation of the particular morphologies and nanostructures of ZnS. This synthesis method could be employed for preparation of other semiconductor nanomaterials. [Copyright &y& Elsevier]

Abstract: The cubic PbS nanoflowers were successfully synthesized by the biomolecule-assisted method in the presence of supercritical carbon dioxide. This is an effective, simple and green synthetic method for the preparation of nanomaterials. It is noteworthy that the dosage of cetyltrimethylammonium bromide (CTAB) and chitosan as well as appropriate reaction time and pressure of system are crucial to form the unusual nanoflower structured PbS. The unique nanoflowers have numerous petals, which grow along the 〈100〉 direction as a single crystal. Especially, the nanoflower PbS indicates better sensitivity to the laser power via Raman spectra. Although the product size of PbS obtained is larger than the Bohr radius, its UV–vis absorption spectrum shows a remarkable blue-shift from that of bulk PbS due to quantum-confinement effects. [Copyright &y& Elsevier]

Abstract: Sn4+-doped FeS2 cubes with high yield thin films have been successfully synthesized on FTO glass through a simple hydrothermal process. The Sn4+-doped FeS2 cubes are single crystalline in cubic structure with (200) facet as the main exposed surface. The formation process was investigated. Sn2+ was found to play an important role during the formation process of FeS2 growing on FTO glass. The direct optical band gap value can be estimated to be 1.71eV which is much larger than that of bulk FeS2 due to the Sn4+ doping. The photoelectrochemical properties of the Sn4+-doped FeS2 films were studied as well. There is a significant increase in photocurrent of Sn4+-doped FeS2 electrode compared to that of undoped sample. [Copyright &y& Elsevier]