Nanoweb Formation: 2D Self‐Assembly of Semiconductor Gallium Oxide Nanowires/Nanotubes

This paper reports a method to produce networks of crystalline gallium oxide comprised of one‐dimensional (1D) nanostructures. Because of the unique arrangement of wires, these crystalline networks are termed as ‘nanowebs’. Nanowebs are of great technological interest since they contain wire densities of the order of 10⁹ cm^–2. A possible mechanism for the fast self‐assembly of crystalline metal oxide nanowires involves multiple nucleation and coalescence via oxidation–reduction reactions at the molecular level. The preferential growth of nanowires parallel to the substrate enabled them to coalesce into regular polygonal networks. The individual segments of the polygonal network consist of both nanowires and nanotubules of β‐gallium oxide. Individual wire properties contribute to a nanoweb’s overall capacity and the implications for devices based on nanowebs are expected to be enormous.     

Self-assembly of highly oriented palladium-based nanowires on mica surface

The self-assembly of various nanostructures is recently attracting a great deal of research attention. In this paper, we demonstrate that a palladium chloride aqueous solution, mixed with a proper ammonia solution, can produce Tetra-amminepalladous chloride (Pd(NH₃)₄Cl₂·H₂O) nanowires. These nanowires can spontaneously form the two-dimensional hexagon-oriented Pd(NH₃)₄Cl₂·H₂O arrays on mica surfaces. We can control the length and height of these nanowires by adjusting their deposit time on the mica substrate. This method can be potentially used in making sensors or in making templates to wire and position nanodevices.     

Effect of SiCnws on flexural strength of SiCf/HfC-SiC composites after impact and ablation

SiC nanowires (SiC_nws) modified SiC_f/HfC-SiC composites were prepared by precursor infiltration and pyrolysis (PIP) and chemical vapor infiltration (CVI) methods. The microstructure, flexural strengths, impact and impact-ablation tests of the composites with and without SiC_nws were investigated. The results showed that after introducing SiC_nws, not only the retention rate of HfC ceramic produced by PIP was increased obviously, but also the fracture displacement of the modified composites was reduced due to the enhancement effect of SiC_nws at interface between SiC fiber and matrix. After impact and impact-ablation, the strength retention of SiC_nws modified composites was 91.6 % and 69.1 % respectively, higher than that of the composites without SiC_nws (85.2 % and 54.8 %). As the impact resistance of the modified composites was improved by the pull-out and bridging of SiC_nws, the ablation resistance of the impacted composites was enhanced as well.     

Multiwalled carbon nanotubes grafted chitosan nanobiocomposite: A prosperous functional nanomaterials for glucose biosensor application

Multiwalled carbon nanotubes (MWNTs) grafted chitosan (CS) nanowire (NW) was prepared by phase separation method. Glucose oxidase (GOx) was sequentially immobilized into MWNT-CS-NW to obtain MWNT-CS-NW/GOx biosensor. Field emission scanning electron microscopy (FESEM) images of MWNT-CS-NW/GOx reveals the existence of MWNT and CS. Cyclic voltammetry and amperometry were used to evaluate the electrochemical determination of glucose. The MWNT-CS-NW/GOx biosensor shows an excellent performance for glucose at +0.34 V with a high sensitivity (5.03 μA/mM) and lower response time (3 s) in a wide concentration range of 1-10 mM (correlation coefficient of 0.9988). In addition, MWNT-CS-NW/GOx biosensor possesses better reproducibility, storage stability and there is negligible interference from other electroactive components.     

Adsorption of polymers at nanowires

Low-energy structures of a hybrid system consisting of a polymer and an attractive nanowire substrate as well as the thermodynamics of the adsorption transition are studied by means of Monte Carlo computer simulations. Depending on structural and energetic properties of the substrate, we find different adsorbed polymer conformations, amongst which are spherical droplets attached to the wire and monolayer tubes surrounding it. We identify adsorption temperatures and the type of the transition between adsorbed and desorbed structures depending on the substrate attraction strength.     

Simple and cost-effective fabrication of two-dimensional plastic nanochannels from silica nanowire templates

Nanofluidic systems are attracting a great deal of interest due to their fundamental significance and potential applications in chemistry, biology and physics. However, high fabrication cost, expensive equipments and complicated fabrication process of most current fabrication techniques prevent lots of researchers from entering the nanofluidic field. Here we present a quick, simple and cost-effective method for fabricating two-dimensional (2D) nanochannel in polycarbonate (PC) substrates. Silica nanowires, taper-drawn from commercially available single-mode fiber were used as templates and embedded in the PC substrate by hot embossing. The nanochannels were created after removing the nanowires by hydrofluoric acid (HF) etching. Poly(dimethylsiloxane) (PDMS) was used to seal the nanochannel reversibly. Nanochannels with widths range from 100 to 900 nm and lengths up to several millimeters were obtained. Various nanostructures including integrated micro and nanochannels, nanochannel array, bent nanochannel and cross-shaped nanochannel were fabricated and characterized by fluorescent microscope, scanning electron microscope (SEM) and atomic force microscope (AFM).     

PtIr alloy nanowire assembly on carbon cloth as advanced anode catalysts for methanol oxidation

The interconnecred PtIr alloy nanowires were uniformly deposited on carbon cloth via One-step wet chemistry method, which diameter is averaged to be 5 nm with a length of 50–200 nm. The carbon cloth supported PtIr nanowire assembly (PtIr NA/CC) shows a larger electrochemical active surface area (ECSA) due to its 3D nanostructure and a high CO-resistance as a result from the synergistic effect of PtIr alloy. The PtIr NA/CC exhibits an extremely high mass activity and a reliable long-term stability toward methanol oxidation reaction (MOR). The superior catalytic performance on MOR can match and even surpass those best Pt-based nanowires reported recently in the literature.     

In-situ deposition of zinc oxide nanowires onto UV-cured chitin derivatives and their antibacterial properties

ZnO nanowires were synthesized on UV-cured chitin film by using a hydrothermal method. Structural and optical characterization showed that one dimensional nanowires can be produced on the UV-cured chitin film. The morphological analysis indicated that nanowires structures can be obtained at about 30 nm radius and 10 µm length. Surface morphology of the ZnO coated UV-cured chitin film was also investigated and a three-dimensional surface profile and high surface roughness were obtained. X-ray diffraction analysis of the film showed large and pure crystals of ZnO nanowires with wurtzite structure and UV–visible absorbance spectrum indicated that ZnO nanowires have 3.39 eV band-gap energy and nanostructures have very good transparency of about 80% in blue region. Also ZnO coated film was tested for its biocidal action against Gram positive Staphylococcus aureus using an agar plate method. This newly developed nano-biomaterial exhibited a strong antibacterial effect.