Yuliang Zhang

Ultrafast synthesis of highly luminescent green- to near infrared-emitting CdTe nanocrystals in aqueous phase

It is commonly observed that the “traditional” aqueous solution route to prepare CdTe nanocrystals (NCs) using thiol ligands as capping reagents is usually very time-consuming and the luminescent properties are poor in the deep red to near infrared (NIR) emission window. Herein, we present an ultrafast and facile aqueous phase route under atmospheric pressure to prepare high-quality green- to NIR-emitting CdTe NCs with mercaptopropionic acid as capping reagent. In contrast to previous reports, red- to NIR-emitting CdTe NCs with emission efficiency up to 50% can be obtained within 1 h reflux time under the optimized experimental conditions. The growth rate is about 100 times faster than those reported previously. The influences of various experimental variables, including Te-to-Cd ratio, ligand-to-Cd ratio, pH value as well as the precursor concentration, on the growth rate and luminescent properties of the obtained CdTe NCs have been systematically investigated. Experimental results indicate that the combination of high pH value and low Te-to-Cd molar ratio plays a crucial role in determining the fast growth rate and the high-quality optical properties of the obtained CdTe NCs. The mechanism for the fast growth rate and the resulting high-quality optical properties is also elucidated.

Preparation of highly luminescent CdTe/CdS core/shell quantum dots.

An effective shell-coating route is developed for covering oil-soluble CdTe quantum dots (QDs), which usually tend to aggregate during the heating-up process involved in shell formation. The new route is based on balancing the coordinating capacity and the activation effect of selected surfactants. The thus obtained highly luminescent CdTe/CdS core/shell QDs exhibit photoluminescence quantum yields as high as 92%--among the best results obtained so far for luminescent semiconductor nanocrystals. By changing the size of the CdTe core, or the thickness of the CdS shell, the emission colors of the obtained core/shell nanocrystals can be tuned between the visible and near-infrared regions of the spectrum following an identical procedure.

Alcoholysis route to monodisperse CoO nanotetrapods with tunable size

Monodisperse tetrapod-shaped CoO nanocrystals were prepared via the alcoholysis of cobalt (III) oleate in dodecanol at high temperature. The coordinating solvent dodecanol also acts as a reducing and morphology controller reagent. The size of the obtained CoO nanotetrapods can be well tuned by variation of the amount of dodecanol used. The chemical composition, structure and morphology of the obtained nanocrystals were characterized by using energy-dispersive x-ray analysis, powder x-ray diffraction, and transmission electron microscopy.

Structural evolution from CuS nanoflowers to Cu9S5 nanosheets and their applications in environmental pollution removal and photothermal conversion

Three-dimensional (3D) CuS nanoflowers and 2D single crystalline Cu9S5 nanosheets with irregular hexagonal holes have been successfully synthesized by easily hydrothermally treating a solution of copper dichloride dihydrates and thiourea at 180 °C for several hours without any surfactants and morphology-controlling agents. Irregular hexagonal holes were widely distributed over the Cu9S5 nanosheets, which could efficiently enlarge the surface area. The UV-vis-NIR absorption spectroscopy showed an obvious increase of the near-IR absorbance. The influence of the reaction time, morphology, and crystal phase on the photocatalysis and photothermal conversion was discussed. The results revealed that CuS nanoflowers displayed the maximum removal value of rhodamine B of 67%. The Cu9S5 nanosheets obtained with the increase reaction time displayed an adsorption and photo-degradation decrease for RhB. The exposure of the aqueous dispersion of the Cu9S5 nanosheets prepared with 6 h (2.0 g L−1) under the irradiation of a 980 nm laser can increase its temperature by 25.1 °C in 600 s, exhibiting a good photothermal conversion performance. The photothermal efficacy increases with the samples obtained from 1 h to 18 h.

Mn-doped ZnO nanonails and their magnetic properties.

Mn-doped ZnO nanonails composed of hexagonal caps and shafts with large doping concentrations from 11.7 to 35.1 at.% were synthesized via a simple and straightforward non-aqueous solution-based route. The chemical composition, morphology and structure of the obtained nanocrystals were characterized by energy-dispersive x-ray analysis, powder x-ray diffraction and transmission electron microscopy. The results show that the nanonails possess a single-crystal wurtzite structure. Electron paramagnetic resonance results indicate that Mn(2+) ions substitute for the zinc sites in the ZnO matrix, which is also confirmed by high-resolution electron microscopy. Thermal tolerance experiments show that the Mn-doped nanonails can maintain their crystalline structure up to 700 degrees C. The influence of reaction conditions on the size and shape of the ZnO-based samples has been investigated in detail, and the possible growth mechanism of the nanonails has also been discussed.

Copper Sulfide-Based Plasmonic Photothermal Membrane for High-Efficiency Solar Vapor Generation

Solar vapor generation has attracted tremendous attention as one of the most efficient ways of utilizing solar energy. It is highly desirable to develop low-cost, eco-friendly, and high-efficiency solar absorbers for practical applications of solar vapor generation. Herein, a three-dimensional plasmonic covellite CuS hierarchical nanostructure has been synthesized as the light-absorbing material via a facile one-pot hydrothermal method for structurally integrated solar absorbers with microporous poly(vinylidene fluoride) membrane (PVDFM) as the supporting material. A broadband and highly efficient light absorption has been achieved in the wavelength of 300-2500 nm, along with high water evaporation efficiencies of 90.4 ± 1.1 and 93.3 ± 2.0% under 1 and 4 sun irradiation, respectively. Meanwhile, stable performance has been demonstrated for over 20 consecutive runs without much performance degradation. To the best of our knowledge, this is the highest performance among the copper sulfide-based solar absorbers. With the additional features of low-cost and convenient fabrication, this plasmonic solar absorber exhibits a tremendous potential for practical solar vapor generation.

A ring-like coordination structure constructed by Cu(II) and bis(2-(pyridin-2-ylthio)ethyl)ether ligand

The reaction of bis(2-(pyridin-2-ylthio)ethyl)ether (L) with CuCl2 in CH3OH/CHCl3 solution gives a novel 24-membered ring-like coordination structure which has been characterized by elemental analysis, IR, and X-ray single-crystal diffraction. The X-ray diffraction analysis reveals that [Cu2L2Cl4] crystallizes in the triclinic, space group

Structural Evolution of Manganese Oxides via Surfactant-Free Solvothermal Routes

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Fabrication of the Nanoparticles of the Cu (II), Zn (II) Complexes with Pyrithione Derivative and their Marine Biological Activities

. The ring-like structure is consisted of two ligands with two copper ions coordinated to the pyridyl nitrogen atoms from two ligands respectively. The largest diameters of the planarshaped dinuclear ring are about 12.7 Å. The adjacent ring-like units are linked via C-H…O hydrogen bonds to generate an infinite linear chain, which are further linked by C-H…Cl hydrogen bonds and weak intermolecular interactions to form a three-dimensional network.

Containing Manganese DMSs Nanostructures via a Nonaqueous Route

The preparation of γ-MnOOH nanorod and Mn3O4 nanooctahedra have been achieved via hydrothermal reaction between KMnO4 and DMF in water without the use of any surfactant or template. Various measurements were used to characterize the structure, morphology and electrochemical behavior of the resultant products. A possible growth mechanism has been proposed, the reaction temperature and the concentration of DMF plays a crucial role in the formation of the products. Their electrochemical properties have also been discussed.