Search results for " Transmission Electron Microscopy"
showing 10 items of 143 documents
Anatase photocatalyst with supported low crystalline TiO2: The influence of amorphous phase on the activity
2018
Abstract In a previous study on commercial TiO2 nanoparticles (J. Soria et al.) we had shown that the superficial disordered layers influence their textural and reactivity features. In the present work we used well crystallized anatase particles (commercial TiO2, BDH) as support of different amounts of titania powders, prepared by TiCl4 hydrolysis and constituted by nanocrystals diluted into an amorphous matrix. The reactivity of these photocatalysts has been tested for the selective oxidation of 4-methoxybenzyl alcohol to aldehyde in aqueous suspension. The catalyst characteristics have been studied using adsorption-desorption isotherms, TEM, HRTEM, TGA, PL, DRIFT-IR, and 1H MAS-NMR spectr…
Hydrogen peroxide sensors for cellular imaging based on horse radish peroxidase reconstituted on polymer-functionalized TiO2 nanorods
2011
We describe the reconstitution of apo-horse radish peroxidase (apo-HRP) onto TiO2 nanorods functionalized with a multifunctional polymer. After functionalization, the horse radish peroxidase (HRP) functionalized TiO2 nanorods were well dispersible in aqueous solution, catalytically active and biocompatible, and they could be used to quantify and image H2O2 which is a harmful secondary product of cellular metabolism. The shape, size and structure of TiO2 nanorods (anatase) were analyzed by transmission electron microscopy (TEM), high resolution TEM (HRTEM), electron diffraction (ED) and X-ray diffraction (XRD). The surface functionalization, HRP reconstitution and catalytic activity were con…
Multifunctional polymer-derivatized γ-Fe2O3 nanocrystals as a methodology for the biomagnetic separation of recombinant His-tagged proteins
2008
Abstract Multifunctional polymer-derivatized superparamagnetic iron oxide (γ-Fe2O3) nanoparticles were prepared for biomagnetic separation of histidine-tagged recombinant proteins building up a faster and efficient method for protein separation by making use of their intrinsic magnetic properties. Using polymer bound γ-Fe2O3 nanocrystals, a 6× histidine-tagged recombinant protein (silicatein) with a molecular weight of 24 kDa has been isolated and purified. The supermagnetic iron oxide nanocrystals were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), SQUID and Mossbauer and the polymer functionalization of the γ-Fe2O3 nanocrystals was monitored by UV–vi…
Growth of fibrous aggregates of silica nanoparticles: Fibre growth by mimicking the biogenic silica patterning processes
2009
We describe the self-assembly of discrete SiO2 nanofibers via grafting of silicatein side chains to a polymer backbone. The covalent binding of silicatein to the backbone of the polymer is based on the affinity of the nitrilotriacetic acid (NTA) side chain, which serves as a ligand for the immobilization of His-tagged silicatein. The surface charge and the bulkiness of the protein moieties prevent the entropically favoured coil formation of the polymer and force it to adopt an open chain structure after hydrolysis of the silica precursors. The probes were characterized by scanning force microscopy (SFM) and optical light microscopy. Surface complexation of the resulting silica nanoparticles…
Use of transmission electron microscopy to obtain quantitative information about polymers
2005
In the polymer field the electron microscope is frequently used as a tool for obtaining purely qualitative data, but only rarely to obtain quantitative information. In order to discuss the potential of this instrument for the latter purpose it is convenient to separate the discussion into the following sub-sections.
Investigation of Activities for Pt-M Bimetallic Nanoparticles Catalysts on the Oxygen Reduction Reaction
2015
Bi-metallic Pt3Ni/C and Pt3Co/C electrocatalysts were successfully synthesized by a solvent free chemical vapour deposition method with a narrow particle size distribution. The results showed that the electrochemical surface area was increased by adding the additional Ni or Co to a pure Pt catalyst. Pt3Ni/C catalyst exhibited a significant enhancement of oxygen reduction reaction activity. The catalysts were characterized by EDS, XRD, HRTEM and electrochemical activity was determined using cyclic voltammetry.
From Single Molecules to Nanoscopically Structured Materials: Self-Assembly of Metal Chalcogenide/Metal Oxide Nanostructures Based on the Degree of P…
2011
A chemically specific and facile method for the immobilization of metal oxide nanoparticles onto the surface of IF-MoS2 nested fullerenes is reported. The modification strategy is based on the chalcophilic affinity of transition metals such as Fe2+/Fe3+, Fe3+, or Zn2+ as described by the Pearson HSAB concept. The binding capabilities of the 3d metals are dictated by their Pearson hardness. Pearson hard cations such as Fe3+ (Fe2O3) do not bind to the chalcogenide surfaces; borderline metals such as Fe2+ (Fe3O4) or Zn2+ (ZnO) bind reversibly. Pearson-soft metals like Au bind irreversibly. The immobilization of metal oxide nanoparticle colloids was monitored by transmission electron microscopy…
Eco-friendly cavity-containing iron oxides prepared by mild routes as very efficient catalysts for the total oxidation of VOCs
2018
Iron oxides (FeOx) are non-toxic, non-expensive and environmentally friendly compounds, which makes them good candidates for many industrial applications, among them catalysis. In the present article five catalysts based on FeOx were synthesized by mild routes: hydrothermal in subcritical and supercritical conditions (Fe-HT, Few200, Few450) and solvothermal (Fe-ST1 and Fe-ST2). The catalytic activity of these catalysts was studied for the total oxidation of toluene using very demanding conditions with high space velocities and including water and CO2 in the feed. The samples were characterized by X-ray diffraction (XRD), scanning and high-resolution transmission electron microscopy (SEM and…
Chemically Selective Imaging of Individual Bonds through Scanning Electron Energy-Loss Spectroscopy : Disulfide Bridges Linking Gold Nanoclusters
2020
As proof-of-principle of chemically selective, spatially resolved imaging of individual bonds, we carry out electron energy-loss spectroscopy in a scanning transmission electron microscopy instrument on atomically precise, thiolate-coated gold nanoclusters linked with 5,5′-bis(mercaptomethyl)-2,2′-bipyridine dithiol ligands. The images allow the identification of bridging disulfide bonds (R–S–S–R) between clusters, and X-ray photoelectron spectra support the finding. peerReviewed
Investigation on the stability of dispersion of zirconia nanoparticles prepared by microwave- hydrothermal synthesis
2005
Difficulties in reproducing the performances of nanoparticles dispersions are obstructive for the progress of the nanotechnology. A plausible reason for this variability is the lack of the control of the stability as well as the dimensions of the nanoparticles in the dispersions. In this work we report results of investigations on the stability of zirconia nanoparticles in aqueous medium, monitoring nanoparticles sizes by means of Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS). Nanocrystalline zirconia powders, prepared by microwave-hydrothermal synthesis, were determined to be 6-8 nm in size by TEM observations. By using DLS technique the as-prepared dispersions wit…