Search results for "nanostructure"
showing 10 items of 792 documents
Structural and electronic properties of single-walled AlN nanotubes of different chiralities and sizes
2006
Four models of single-walled AlN nanotubes (NTs), which possess (i) two different chiralities (armchair or zigzag type) and (ii) two different uniform diameters for both types of NTs (1 or 6 nm) have been constructed, in order to analyse the dependence of their properties on both morphology and thickness. Periodic one-dimensional (1D) DFT calculations performed on these models have allowed us to analyse how the chirality and curvature of the NT change its properties as compared to both AlN bulk with either wurtzite or zinc-blende structures and their densely packed surfaces. We have found that the larger the diameter of the AlN NT, the smaller the width of its bandgap, the strengths of its …
Nanomaterials for use in immunosensing of carcinoembryonic antigen (CEA): Recent advances
2017
Abstract This review (with 86 refs.) covers the state of the art in electrochemical and optical immunoassay of carcinoembryonic antigen (CEA). The purpose of the review is to provide useful insights in terms of (a) choice of materials, (b) methods/techniques preferably applied, (c) immunological procedures, (d) immobilization procedures, and (d) other practical aspects. Following an introduction into the field, we give a short account on the principle and general types of immunoassay, and then treat immunoassay for CEA. The first section covers nanomaterial based electrochemical immunoassay, with subsections on using of nanoparticles, hyperbranched polymers, graphene and their derivatives f…
Structural characterization of one-dimensional ZnO-based nanostructures grown by MOCVD
2010
Various one-dimensional (1D) ZnO-based nanostructures, including ZnO nano-wires (NWs) grown using vapour-liquid-solid (VLS) process, ZnO/ZnSe core/shell, nitrogen-doped ZnO and ZnMgO NWs were grown by metalorganic chemical vapour deposition (MOCVD). Transmission electron microscopy (TEM) analysis is presented. For all the samples, a high crystalline quality is observed. Some features are emphasized such as the gold contamination of ZnO wires grown under the metal droplets in the VLS process. It is concluded that MOCVD is a suitable technique for the realization of original ZnO nanodevices.
Combustion Formation of Novel Nanomaterials: Synthesis and Cathodoluminescence of Silicon Carbide Nanowires
2009
This paper presents the combustion synthesis and characterization of one-dimensional silicon carbide nanostructures (nanowires of 3C-SiC polytype with zincblend structure) by means of cathodoluminescence technique. Cathodoluminescence spectra of nano-SiC samples and, as a reference, of a commercially available SiC micropowder are compared. It is shown that the emission band at 1.97 eV which is slightly evidenced in the spectrum of the commercial SiC under 10 keV electron beam irradiation becomes the prevailing band in CL of the purified silicon carbide nanowires.
Surface waves in plasmonic anisotropie media
2012
We investigate the spatial dispersion of hybrid-polarized surface waves excited at the boundary of a semi-infinite layered metal-dielectric nanostructure. We put emphasis in the case that the thickness of a metal layer becomes of the order of the metal skin depth. We demonstrate that the use of the so-called effective medium approximation (EMA) is not justified, in general. For that purpose, we compare the results using the EMA model and numerical simulations based on the finite-element method. We include an analysis of the influence of metallic losses.
Plasmon-assisted spin transition in gold nanostar@spin crossover heterostructures
2021
Aquí presentamos el diseño de nanopartículas core@shell formadas por un núcleo de nanoestrella de Au metálico y una capa cruzada de espín basada en el polímero de coordinación [Fe(Htrz)2(trz)](BF4). Este procedimiento es general y se ha extendido a otras morfologías metálicas (nanovarillas, nanotriángulos). Gracias al efecto fototérmico derivado de las propiedades plasmónicas de la nanoestrella de Au, el 60 % de los centros de hierro experimentan una transición de espín térmico dentro de la histéresis térmica provocada por una irradiación de baja intensidad con un láser de 808 nm. En comparación con otras morfologías de Au, la gran ventaja de la forma de nanoestrella surge de los puntos cal…
Self-templated synthesis of novel carbon nanoarchitectures for efficient electrocatalysis
2016
AbstractThe cost-efficient large-scale production of novel carbon nanostructure with high performance is still a challenge, restricting their applications in catalysis. Herein, we present a low-cost one-pot and one-step approach for the synthesis of both N-doped graphene (NG) and N-doped carbon nanotubes (NCNTs) from self-templated organic nanoplates. By varying the FeCl3 concentration in the precursor, we can control the formation of graphene or CNTs. To the best of our knowledge, this is the first example for the controllable synthesis of graphene or CNTs by varying the precursors’ compositions. This provides a simple and cost-effective route for the large-scale production of both NG and …
Improvement in photocatalytic activity of stable WO3 nanoplatelet globular clusters arranged in a tree-like fashion: Influence of rotation velocity d…
2016
This study investigates the influence of controlled hydrodynamic conditions during anodization of tungsten (W) on the morphological, electrochemical and photocatalytic properties of a novel WO3 nanostructure: globular clusters of nanoplatelets associated in a tree-like fashion. For this purpose different techniques such as Field-Emission Scanning Electronic Microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS) measurements, Mott-Schottky (M-S) analysis and photoelectrochemical water splitting tests have been carried out. Photoanodes obtained at 375 rpm showed the best photoresponse, much higher than that of conventional WO3 nanoplatelets, which can be ascribed to a noteworthy in…
Fourth‐generation glucose sensors composed of copper nanostructures for diabetes management: A critical review
2022
Abstract More than five decades have been invested in understanding glucose biosensors. Yet, this immensely versatile field has continued to gain attention from the scientific world to better understand and diagnose diabetes. However, such extensive work done to improve glucose sensing devices has still not yielded desirable results. Drawbacks like the necessity of the invasive finger‐pricking step and the lack of optimization of diagnostic interventions still need to be considered to improve the testing process of diabetic patients. To upgrade the glucose‐sensing devices and reduce the number of intermediary steps during glucose measurement, fourth‐generation glucose sensors (FGGS) have be…
Covalently Conjugated Gold-Porphyrin Nanostructures
2020
Gold nanoparticles show important electronic and optical properties, owing to their size, shape, and electronic structures. Indeed, gold nanoparticles containing no more than 30&ndash