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Shu-Hong Yu

Publications and source records attributed to Shu-Hong Yu.

At least 19 recordsLinked to original sources
PubMed2007

Recrystallization and shape control of crystals of the organic dye acid green 27 in a mixed solvent.

Recrystallization of the unstructured dye acid green 27 (AG27) in a mixed solvent of alcohol (ethanol or methanol) and water was systematically studied. The results demonstrated that AG27 crystals with uniform sizes and controllable shapes can be produced by simply changing the volume ratio of ethanol (or methanol) and deionized water (DIW). Rodlike and shuttlelike AG27 crystals can be selectively synthesized. The XRD analyses revealed the periodic structures of the organic crystals. Furthermore, crystallization in another mixed solvent of N,N-dimethylformamide (DMF) and DIW results in the formation of longer fibers with high aspect ratio, which further validates the remarkable effects of mixed solvent on the shape of the AG27 crystals. This method of recrystallization in a mixed solvent is expected to facilitate the synthesis of other functional organic crystals with unusual shapes.

Journal Article↗
PubMed2007

3D architectures of iron molybdate: phase selective synthesis, growth mechanism, and magnetic properties.

Monoclinic and orthorhombic Fe(2)(MoO(4))(3) microsized particles with complex 3D architectures have been selectively prepared by a template-free hydrothermal process. The pH value, reaction time, temperature, and molybdenian source have crucial influence on the phase formation, shape evolution, and microstructures. Monoclinic Fe(2)(MoO(4))(3) particles obtained at pH 1 and pH 1.65 display ferromagnetic ordering at 10.4 K and 10.5 K, respectively, and the ferromagnetic component is determined to be 0.0458 mu(B) and 0.0349 mu(B) per Fe-ion at 10 K, respectively. For orthorhombic beta-Fe(2)(MoO(4))(3), antiferromagnetic ordering was observed about 12 K. At higher temperatures, beta-Fe(2)(MoO(4))(3) began to follow the Curie-Weiss law with theta=-70 K. Such 3D architectures of monoclinic and orthorhombic beta-Fe(2)(MoO(4))(3) microparticles with unique shapes and structural characteristics may find applications as catalysts and as well as in other fields.

Crystallization↗
PubMed2006

Crystallization and shape evolution of single crystalline selenium nanorods at liquid-liquid interface: from monodisperse amorphous Se nanospheres toward Se nanorods.

The reduction of selenious acid solution with hydrazine hydrate in the presence of poly(vinylpyrrolidone) (PVP) can produce a stable dispersion of uniform and amorphous selenium particles capped with PVP with a size of 100 nm. Further addition of a solvent with low polarity such as n-butyl alcohol into this aqueous solution and mild stirring result in the transportation of amorphous selenium particles onto a liquid-liquid interface between water and n-butyl alcohol. Subsequent crystallization and shape evolution on this interface occurred and finally resulted in the formation of single crystalline selenium nanorods. The results demonstrated that the enrichment of nanoparticles with amphiphilic property at a liquid-liquid interface between a polar solvent and another solvent of low polarity can result in crystallization and phase transformation for the formation of nanostructures.

Journal Article↗
PubMed2006

Double hydrophilic block copolymer controlled growth and self-assembly of CaCO3 multilayered structures at the air/water interface.

Double hydrophilic block copolymers PEG-b-PEI-linear with different PEI block lengths have been examined for CaCO3 mineralization at the air/water interface. The results demonstrated that either PEI length or the solution acidity had a significant influence on the morphogenesis of vaterite crystals at the air/water interface. A possible mechanism for the stratification of CaCO3 vaterite crystals has been proposed. Increasing either PEI length or the initial pH value of the solution will decrease the density of the PEG block anchored on the binding interface and result in exposing more space as binding interface to solution and favoring the subnucleation and stratification growth on the polymer-CaCO3 interface. In contrast, higher density of PEG blocks will stabilize the growing crystals more efficiently and inhibit subnucleation on the polymer-CaCO3 interface, and thus prevent the formation of stratified structures. This study provides an example that it is possible to access morphogenesis of calcium carbonate structures by a combination of a block copolymer with the air/water interface.

Calcium Carbonate↗
PubMed2006

Architectural control syntheses of CdS and CdSe nanoflowers, branched nanowires, and nanotrees via a solvothermal approach in a mixed solution and their photocatalytic property.

Wurtzite CdS and CdSe nanostructures with complex morphologies such as urchin-like CdS nanoflowers, branched nanowires, and fractal nanotrees can be produced via a facile solvothermal approach in a mixed solution made of diethylenetriamine (DETA) and deionized water (DIW). The morphologies of CdS and CdSe nanocrystals can be easily controlled via tuning the volume ratio of DETA and DIW. Urchin-like CdS nanoflowers made of CdS nanorods are in a form of highly ordered hierarchical structures, while the nanowires are branched nanowires, and the fractal CdS nanotrees are a buildup of branched nanopines. The results demonstrated that solvothermal reaction in a mixed amine/water can access a variety of complex morphologies of semiconductor materials. The photocatalytic activity of CdS particles with different morphologies has been tested by the degradation of acid fuchsine under both UV and visible light, showing that the as-prepared branched CdS nanowires exhibit high photocatalytic activity for degradation of acid fuchsine.

Cadmium Compounds↗
PubMed2006

Biomimetic assembly of polypeptide-stabilized CaCO(3) nanoparticles.

In this paper, we report a simple polypeptide-directed strategy for fabricating large spherical assembly of CaCO(3) nanoparticles. Stepwise growth and assembly of a large number of nanoparticles have been observed, from the formation of an amorphous liquidlike CaCO(3)-polypeptide precursor, to the crystallization and stabilization of polypeptide-capped nanoparticles, and eventually, the spherical assembly of nanoparticles. The "soft" poly(aspartate)-capping layer binding on a nanoparticle surface resulted in the unusual soft nature of nanoparticle assembly, providing a reservoir of primary nanoparticles with a moderate mobility, which is the basis of a new strategy for reconstructing nanoparticle assembly into complex nanoparticle architectures. Moreover, the findings of the secondary assembly of nanoparticle microspheres and the morphology transformation of nanoparticle assembly demonstrate a flexible and controllable pathway for manipulating the shapes and structures of nanoparticle assembly. In addition, the combination of the polypeptide with a double hydrophilic block copolymer (DHBC) allows it to possibly further control the shape and complexity of the nanoparticle assembly. A clear perspective is shown here that more complex nanoparticle materials could be created by using "soft" biological proteins or peptides as a mediating template at the organic-inorganic interface.

Biomimetic Materials↗
PubMed2006

Large-scale synthesis of flexible gold/cross-linked-PVA sub-microcables and cross-linked-PVA tubes/fibers by using templating approaches based on silver/cross-linked-PVA sub-microcables.

Well-defined silver/cross-linked-poly(vinyl alcohol) (PVA) sub-microcables, which were synthesized from a hydrothermal reaction using AgCl and PVA as precursors, have been used as sacrificial templates to fabricate gold/cross-linked-PVA sub-microcables by etching the silver/cross-linked-PVA sub-microcables with tetrachloroaurate(III). In addition, well-defined cross-linked-PVA sub-microtubes/sub-microfibers can also be produced by the removal of the silver cores of such sub-microcables at ambient temperature. The channel diameter and the shell thickness could be tuned by controlling the diameter of the core sub-microfibers and the shell thickness of the precursor sub-microcables. These cross-linked-PVA-based cables, tubes, and fibers have the potential to be used in future applications such as nanodevices.

Journal Article↗
PubMed2006

High-quality luminescent tellurium nanowires of several nanometers in diameter and high aspect ratio synthesized by a poly (vinyl pyrrolidone)-assisted hydrothermal process.

Large-scale selective synthesis of uniform single crystalline tellurium nanowires with a diameter of 4-9 nm, and microbelts with a width of 250-800 nm and tens of micrometers in length, can be realized by a poly (vinyl pyrrolidone) (PVP)-assisted hydrothermal process. The formation of tellurium nanowires and nanobelts in the presence of PVP is strongly dependent on the reaction conditions such as temperature, the amount of PVP, and reaction time. The results demonstrated that the keys for selective synthesis of Te nanobelts and nanowires are to modulate the growth rates of (100), (101), and (110) planes in the presence of PVP and to precisely control the reaction kinetics. High-quality luminescent ultrathin t-Te nanowires with a diameter of 4-9 nm display strong luminescent emission in the blue-violet region. This approach provides a facile route for the production of high-quality tellurium nanostructures with an interesting optical property. Furthermore, the synthesized ultrathin nanowires with deep blue color and nanobelts in gray color by this approach can be well dispersed in water or ethanol, making it possible for further engineering of their surfaces to prepare other hybrid core-shell nanostructures.

Journal Article↗
PubMed2006

Block-copolymer-controlled growth of CaCO3 microrings.

A novel way for directed solution growth of hollow superstructures of CaCO3 has been successfully developed on the basis of controlled self-assembly and polymer concentration gradients using a double-hydrophilic block copolymer with a hydrophobic modification as a directing agent. A formation mechanism of such rings is proposed on the basis of the formation of CaCO3 nanoparticles in unstructured block copolymer assemblies with subsequent aggregation of these primary nanoparticles. This leads to the formation of a polymer concentration gradient from the inside to the outside of the particle. As the polymer contains multiple chelating units, this leads to a selective dissolution of the center of the particle.

Calcium Carbonate↗
PubMed2006

Hexamethylenetetramine directed synthesis and properties of a new family of alpha-nickel hydroxide organic-inorganic hybrid materials with high chemical stability.

A new family of organic-inorganic hybrid material of alpha-nickel hydroxide formulated as Ni(OH)2-x(An-)x/n-(C6H12N4)y.zH2O (A=Cl-, CH3COO-, SO4(2-), NO3-; x=0.05-0.18, y=0.09-0.11, z=0.36-0.43) with high stability and adjustable interlayer spacing ranging from 7.21 to 15.12 A has been successfully prepared by a simple hydrothermal method. The effects of various anions and hexamethylenetetramine (HMT) on the d values of alpha-nickel hydroxide have been systematically investigated. This family of hybrid materials is of such high stability that they can stand more than 40 days in 6 M KOH. The product with a formula Ni(OH)1.95(C6H12N4)0.11(Cl-)0.05(H2O)0.36 has a high surface area of about 299.26 m2/g and an average pore diameter of about 45.1 A. The coercivity (Hc) value is ca. 2000 Oe for the sample with a d spacing of 13.14 A. Moreover, the prepared alpha-Ni(OH)2 in our experiment is of high stability in strong alkali solution. Such high stability could be derived from strong chelating interactions between the Ni ions and HMT molecules with the interlayers. This high chemical stability could make this material more suitable for the applications.

Journal Article↗
PubMed2006

Complex wurtzite ZnSe microspheres with high hierarchy and their optical properties.

Complex wurtzite ZnSe microspheres with hierarchical fractal structure and showing strong quantum-size effects can be prepared easily by a mild solvothermal reaction in a diethylenetriamine (DETA)-deionized water (DIW) binary solution. The ZnSe microspheres are made up of nanosheets, each formed by the face-to-face pairing of two individual nanosheets. In addition, high-order, flowerlike hierarchical structures are formed by the attachment of flexible, uniform nanofibers to the exposed faces of each nanosheet pair. The surface morphology of the nanosheets changed as reaction time increased and the detailed phase-transformation and shape-evolution processes were studied. This approach could provide an effective strategy for tuning the electronic and optical properties of semiconductors, with special advantages over the traditional high-temperature approach, and could be extended to access other semiconductor materials with unusual morphologies and structures.

Journal Article↗
PubMed2006

Large scale synthesis of uniform silver@carbon rich composite (carbon and cross-linked PVA) sub-microcables by a facile green chemistry carbonization approach.

A facile green chemistry carbonization method has been discovered for the synthesis of uniform silver@carbon rich composite (carbon and cross-linked polyvinyl alcohol) core-shell sub-microcables in large quantities, where the carbon sources such as glucose-based saccharides have played important roles in the formation of these novel sub-microcables.

Journal Article↗
PubMed2005

Large scale synthesis of tellurium nanoribbons in tetraethylene pentamine aqueous solution and the stability of tellurium nanoribbons in ethanol and water.

Superlong single crystal tellurium nanoribbons with a width of 200-300 nm and length up to several hundred micrometers have been synthesized in tetraethylene pentamine aqueous solution at 80 degrees C. The stability of as prepared tellurium nanoribbons in solvents such as pure ethanol and deionized water has been studied. The poor crystallinity of the initial single crystalline Te nanoribbons with prolonged storing time demonstrated that the initial single crystalline nanobelts tend to be destroyed and to dissolve in the solvent. In meantime, the supersaturation of the solvable Te species in such solvents will result in the formation of amorphous Te, and the formation of amorphous TeO2 due to partial oxidation of the Te nanostructures and the newly formed amorphous Te. The detailed corrosion process, crystallinity, and shape evolution process have been carefully examined by the XRD, TEM, HRTEM, and XPS techniques. This erosion phenomenon attacked by solvents has been not identified previously, suggesting that tellurium nanoribbons synthesized by other chemical methods could be also not stable in solution system and their storage after laboratory synthesis requires special attention.

Journal Article↗
PubMed2005

Complex PbTe hopper (skeletal) crystals with high hierarchy.

A facile and mild solution method has been discovered for the synthesis of complex PbTe hopper crystals in large quantities, which are highly similar to the cubic halite skeletal crystals formed from extreme supersaturation in salt lakes existing in nature. This route may provide a new approach to growing other complex semiconductor structures of high hierarchy.

Journal Article↗
PubMed2005

Formation of uniform CuO nanorods by spontaneous aggregation: Selective synthesis of CuO, Cu2O, and Cu nanoparticles by a solid-liquid phase arc discharge process.

Uniform and monodisperse CuO nanorods have been synthesized by directional aggregation and crystallization of tiny CuO nanoparticles generated from a solid-liquid arc discharge process under ambient conditions in the absence of any surfactants. Uniform CuO nanorods with sharp ends are formed from tiny nanoparticles via a process that involves the rapid oxidation of Cu nanoclusters, the spontaneous aggregation of CuO nanoparticles, and the Ostawald ripening process. The spontaneous aggregation and oriented attachment of tiny CuO nanoparticles contributed obviously to the formation of these kinds of nanostructures. By choice of suitable reducing agent to prevent the oxidation of Cu nanoclusters, Cu and Cu2O nanoparticles can be selectively synthesized.

Journal Article↗