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Tunable Morphologies (tunable + morphology)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Tetraethylenepentamine-Directed Controllable Synthesis of Wurtzite ZnSe Nanostructures with Tunable Morphology

CHEMISTRY - A EUROPEAN JOURNAL, Issue 31 2008
Baojuan Xi Dr.
Abstract A novel tetraethylenepentamine (TEPA)-directed method has been successfully developed for the controlled synthesis of ZnSe particles with distinctive morphologies, including nanobelts, nanowires, and hierarchically solid/hollow spheres. These structures, self-assembled from nanobelts and nanorods, have been synthesized by adjusting the reaction parameters, such as the solvent composition, reaction temperature, and the aging time. Results reveal that the volume ratio of H2O and TEPA plays a crucial role in the final morphology of ZnSe products. The mechanisms of phase formation and morphology control of ZnSe particles are proposed and discussed in detail. The products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), selected area electron diffraction, high-resolution TEM, Raman spectra and luminescence spectroscopy. The as-prepared ZnSe nanoparticles display shape- and size-dependent photoluminescent optical properties. This is the first time to report preparation of complex hollow structures of ZnSe crystals with hierarchy through a simple solution-based route. This synthetic route is designed to exploit a new H2O/TEPA/N2H4,H2O system possibly for the preparation of other semiconductor nanomaterials. [source]

Microstructured Arrays of TiO2 Nanotubes for Improved Photo-Electrocatalysis and Mechanical Stability

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009
Daoai Wang
Abstract The preparation of micropatterned TiO2 nanotubes (NTs) with tunable morphologies by combining laser micromachining technology and an anodization method is reported. The micropatterned structure can be easily designed and fabricated by laser micromachining a titanium substrate, further anodization of which gives nanotube arrays perpendicularly oriented to the titanium surface. The patterned TiO2 NTs show dramatically improved photocurrent and photocatalytic performances because of their enhanced surface area and light-harvesting capability. The photocurrent density and incident-photon-to-current efficiency at the peak absorption increases by 48 and 39%, respectively, compared to a TiO2 NT array without a patterned structure. It was also found that micropatterning dramatically improves the mechanical stability of the TiO2 NTs on the substrate, which otherwise were liable to peel off from the substrate surface. The strategy will reasonably expand the application of TiO2 NTs in a variety of fields that require enhanced photo-electrocatalysis and mechanical stability. [source]

Nanolayered Carbon/Silica Superstructures via Organosilane Assembly

ADVANCED MATERIALS, Issue 6 2008
Huisheng Peng
Nanolayered carbon/silica superstructures with tunable morphologies (tubes, fibers, or spheres) and sizes (micro-sized or macroscopic) were synthesized by self-assembly of perylenedidimide-bridged silsesquioxane through an easy sol-gel process followed by carbonization. The derived nanocomposite materials show interesting electrical properties, i.e., the conductivity increases exponentially with temperature. [source]

General Strategy for a Large-Scale Fabric with Branched Nanofiber,Nanorod Hierarchical Heterostructure: Controllable Synthesis and Applications

CHEMISTRY - A EUROPEAN JOURNAL, Issue 37 2010
Meng Shang
Abstract The preparation and characterization of a branched nanofiber,nanorod hierarchical heterostructure fabric (TiO2/NiO, TiO2/ZnO, and TiO2/SnO2) are described. The nanomaterial was synthesized on a large scale by an inexpensive, generalizable, facile, and controllable approach by combining the electrospinning technique with a hydrothermal method. The controllable formation process and factors (assistance by hexamethylenetetramine and metal oxide nuclei) influencing the morphology of the branched hierarchical heterostructure are discussed. In addition, photocurrent and photocatalytic studies suggest that the branched hierarchical heterostructure fabric shows higher mobility of charge carriers and enhanced photocatalytic activity relative to a bare TiO2 nanofibrous mat and other heterostructures under irradiation by light. This work demonstrates the possibility of growing branched heterostructure fabrics of various uniform, one-dimensional, functional metal oxide nanorods on a TiO2 nanofibrous mat, which has a tunable morphology by changing the precursor. The study may open a new channel for building hierarchical heterostructure device fabrics with optical and catalytic properties, and allow the realization of a new class of nano-heterostructure devices. [source]