Chitosan bionanocomposites prepared in the self-organized regime

2015 ◽  
Vol 87 (8) ◽  
pp. 793-803 ◽  
Author(s):  
Irina Postnova ◽  
Sergei Sarin ◽  
Vladimir Silant’ev ◽  
Chang-Sik Ha ◽  
Yury Shchipunov
Keyword(s):  
Three Dimensional ◽  
Multiwall Carbon Nanotubes ◽  
The Self ◽  
Clay Nanoparticles ◽  
Self Organized ◽  
X Ray Scattering ◽  
Novel Approach ◽  
Transmission Electron ◽  
Dimensional Network ◽  
Multiwall Carbon

AbstractBionanocomposites in the self-organized regime are prepared when chitosan is gradually charged in the course of progressive change of pH by hydrolyzing D-glucono-δ-lactone in solutions of nanoparticles bearing negative charges on their surface. This novel approach is applicable to the formation of monolithic hydrogels and films. Here bionanocomposites of chitosan with clay nanoparticles of saponite and sepiolite having various geometry and with oxidized multiwall carbon nanotubes are considered. Structural organization of hydrogels and films is studied by scanning and transmission electron microscopy as well as small angle X-ray scattering. Jellification is caused by generation of three-dimensional network from fibrils, whereas films have pronounced stratified layer (nacre-like) structure from stacked nanoparticles and aligned chitosan macromolecules. Special attention is paid to mechanical properties of films that are improved drastically with introducing nanoparticles.

Studies of Compositional Variations in Germanium Quantum Dots Grown on Silicon

2000 ◽  
Vol 638 ◽  
Author(s):  
Alan D.F. Dunbar ◽  
Matthew P. Halsall ◽  
Uschi Bangert ◽  
Alan Harvey ◽  
Philip Dawson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
The Self ◽  
Asymmetric Distribution ◽  
Scanning Transmission Electron ◽  
Self Organized ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Uk

AbstractWe report optical and scanning transmission electron microscopy studies of germanium dots grown on silicon. In an attempt to control the self-organized growth process and promote dot size uniformity the dot layers were grown on a 4.5nm Si0.6Ge0.4 alloy template layer. Photoluminescence results indicate the formation of carrier confining Ge rich islands, whilst Raman scattering results indicate the presence of an alloy throughout the structures formed. The samples were studied in the UK high resolution scanning transmission electron microscopy facility at Liverpool, UK. Energy dispersive analysis of individual line scans through the sample show that the structures are composed of an alloy throughout with an asymmetric distribution of Germanium in the dots and in the wetting layer close to the dots. We discuss the results in the light of the proposed growth mode for these dots and conclude that attempts to manipulate the composition of these dots during growth may be problematic due to the self-organized nature of their formation.

Self-Organized Composition Modulation In Omvpe Ga1−xInxAsySb1−y/GaSb Epitaxial Heterostructures

1999 ◽  
Vol 583 ◽  
Author(s):  
Y-C. Chen ◽  
V. Bucklen ◽  
K. Rajan ◽  
C. A. Wang ◽  
G. W. Charache ◽  
...  
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Component Composition ◽  
Organometallic Vapor Phase Epitaxy ◽  
Composition Modulation ◽  
Self Organized ◽  
Transmission Electron ◽  
Epitaxial Heterostructures ◽  
20 Nm ◽  
Lattice Matched

AbstractMicrostructures of lattice-matched Ga1−xInxAsySb1−y grown by organometallic vapor phase epitaxy (OMVPE) on (100) 6°→ (111)B GaSb substrates have been examined in detail by transmission electron microscopy. A three-dimensional self-organized composition modulation (SOCM) microstructure was found with an orientation inclined 10 degrees to the surface orientation when viewed in (011) cross-section. The periodicity of the SOCM increased from ˜13 nm to 20 nm, as x increased from 0.1 to 0.2 while the orientation of the SOCM remained the same. The fact that the orientation was not sensitive to the component composition indicated that substrate misorientation plays a major role in deciding this SOCM orientation. This may open fabrication opportunities for three-dimensional natural superlattices by engineering on the substrate misorientation.

Stacking Faults in SiC Nanowires

2008 ◽  
Vol 8 (7) ◽  
pp. 3504-3510 ◽  
Author(s):  
K. L. Wallis ◽  
M. Wieligor ◽  
T. W. Zerda ◽  
S. Stelmakh ◽  
S. Gierlotka ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Stacking Faults ◽  
Multiwall Carbon Nanotubes ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
Ir Spectrometry ◽  
X Ray ◽  
Sic Nanowires ◽  
Transmission Electron ◽  
Multiwall Carbon

SiC nanowires were obtained by a reaction between vapor silicon and multiwall carbon nanotubes, CNT, in vacuum at 1200 °C. Raman and IR spectrometry, X-ray diffraction and high resolution transmission electron microscopy, HRTEM, were used to characterize properties of SiC nanowires. Morphology and chemical composition of the nanowires was similar for all samples, but concentration of structural defects varied and depended on the origin of CNT. Stacking faults were characterized by HRTEM and Raman spectroscopy, and both techniques provided complementary results. Raman microscopy allowed studying structural defects inside individual nanowires. A thin layer of amorphous silicon carbide was detected on the surface of nanowires.

Comparison of Cobalt Based Catalysts Supported on MWCNT and SBA-15 Supporters for Fischer-Tropsch Synthesis by Using Autoclave Type Reactor

2011 ◽  
Vol 364 ◽  
pp. 70-75 ◽  
Author(s):  
Adkham Yakubov ◽  
M.G. Kutty ◽  
Pei Lee Siew ◽  
Maizatul S. Shaharun ◽  
S.B. Abd Hamid ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Multiwall Carbon Nanotubes ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Santa Barbara ◽  
X Ray ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Multiwall Carbon ◽  
Autoclave Reactor

10 and 40 wt% Co/Multiwall Carbon Nanotubes (MWCNT) and 10 and 40 wt% Co/Santa Barbara Amorphous-15 (SBA-15) catalysts were prepared via incipient wetness impregnation method. It was characterized by Scanning Electron Microscopy, BET, X-ray Diffractometry (XRD), Transmission Electron Microscopy (TEM), Temperature-Programmed Reduction and H2Desorption. A 200 ml hastelloy autoclave reactor was implemented to see the performance of the catalysts. It was observed that the performance of 40 wt% Co/SBA-15 was higher that other catalysts in terms of production of longer chain paraffins.

Self-organized in-plane ordering of nanostructures at epitaxial ferroelectric–ferromagnetic interfaces

2016 ◽  
Vol 49 (5) ◽  
pp. 1693-1703 ◽  
Author(s):  
Rasmus Flaschmann ◽  
Jingfan Ye ◽  
Neelima Paul ◽  
Francis Bern ◽  
Pablo Esquinazi ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Repeated Sequence ◽  
Grazing Incidence ◽  
Columnar Structure ◽  
Self Organized ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Self Assembled ◽  
Electron Energy Loss

The formation of self-assembled structures is of great interest in the field of ferroelectric (FE)–ferromagnetic (FM) oxide interfaces with novel functionalities driven by the combination of strain relaxation and diffusion/segregation processes occurring during epitaxial growth of Mn-based heterostructures. In epitaxial bilayers and multilayers of La0.67Sr0.33MnO3 (LSMO)/BaTiO3 (BTO) on (001) SrTiO3, using the grazing-incidence small-angle X-ray scattering technique, self-assembled in-plane structural ordering with a repeated sequence of the bilayers has been found. This ordering has important magnetic consequences, as the materials show characteristics of a superparamagnetic type of behavior even with an increased number of bilayers. Transmission electron microscopy images reveal strain due to lattice mismatch between BTO and LSMO. This strain is greatly enhanced with the number of BTO and LSMO repetitions in a multilayer as an interdiffused columnar structure is formed. Electron energy loss spectra indicate a variation in oxygen environment from one monolayer to another within one LSMO layer. Reflectivity measurements with polarized neutrons prove that the LSMO layers are grown with sufficient periodicity but have a strongly reduced magnetic moment. This reduction is plausibly associated with interfacial strain and varying oxygen deficiencies within the layers or symmetry breaking effects which can turn the LSMO layer almost antiferromagnetic.

scholarly journals Effect of Carboxylic Functional Group Functionalized on Carbon Nanotubes Surface on the Removal of Lead from Water

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Muataz Ali Atieh ◽  
Omer Yehya Bakather ◽  
Bassam Al-Tawbini ◽  
Alaadin A. Bukhari ◽  
Faraj Ahmad Abuilaiwi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Functional Group ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Properties ◽  
Average Diameter ◽  
Transmission Electron ◽  
Physical And Chemical ◽  
Multiwall Carbon ◽  
Carboxylic Functional Group

The adsorption mechanism of the removal of lead from water by using carboxylic functional group (COOH) functionalized on the surface of carbon nanotubes was investigated. Four independent variables including pH, CNTs dosage, contact time, and agitation speed were carried out to determine the influence of these parameters on the adsorption capacity of the lead from water. The morphology of the synthesized multiwall carbon nanotubes (MWCNTs) was characterized by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) in order to measure the diameter and the length of the CNTs. The diameters of the carbon nanotubes were varied from 20 to 40 nm with average diameter at 24 nm and 10 micrometer in length. Results of the study showed that 100% of lead was removed by using COOH-MCNTs at pH 7, 150 rpm, and 2 hours. These high removal efficiencies were likely attributed to the strong affinity of lead to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data.

scholarly journals Effects of Crystallinity on the Photocatalytic Polymerization of 3,4-Ethylenedioxythiophene over CsPbBr3 Inverse Opals

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1331
Author(s):  
Siwei Zhao ◽  
Shaohua Jin ◽  
Huanmin Liu ◽  
Shengfu Li ◽  
Kun Chen
Keyword(s):  
Colloidal Crystal ◽  
Three Dimensional ◽  
Inverse Opal ◽  
Porous Structures ◽  
Novel Approach ◽  
Transmission Electron ◽  
Hierarchical Porous ◽  
Antisolvent Crystallization ◽  
Colloidal Crystal Templating ◽  
High Absorption Coefficient

Due to their high absorption coefficient and long carrier lifetime, halide perovskites are promising candidates for photocatalysts. For this study, the antisolvent crystallization protocol and the colloidal crystal templating approach were combined to fabricate the highly crystalline cesium lead bromide perovskite with inverse opal morphology (IO-CsPbBr3). Scanning electron microscopy and transmission electron microscope images demonstrate the three-dimensional well-ordered porous structures of the IO-CsPbBr3 and their single-crystalline features. The presented approach not only provides hierarchical porous structures but also enhances overall crystallinity. When used as catalysts to promote the polymerization of 2,2′,5′,2″-ter-3,4-ethylenedioxythiophene, the highly crystalline IO-CsPbBr3 exhibits a superior photocatalytic performance compared to its polycrystalline counterpart. Furthermore, the morphology and the crystalline structure of the highly crystalline IO-CsPbBr3 are well preserved under photocatalytic conditions. This novel approach enables the preparation of a halide perovskite inverse opal with high crystallinity.

Facile Synthesis of Bi2S3/MoS2/g-C3N4 Ternary Photocatalysts and Photocatalytic Properties

NANO ◽  
2021 ◽  
pp. 2150085
Author(s):  
Dongen Zhang ◽  
Youxiang Jiang
Keyword(s):  
Rhodamine B ◽  
Diffuse Reflectance Spectroscopy ◽  
Three Dimensional ◽  
Nitrogen Atmosphere ◽  
Photoelectron Spectra ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
X Ray ◽  
Transmission Electron ◽  
Dimensional Network

Bi2S3/MoS2/g-C3N4 nanocomposite was synthesized using a solid-state method for the first time. Thiourea and bulk Bi2MoO6 were used as the precursors and were reacted under a nitrogen atmosphere. Bi2S3/MoS2/g-C3N4 was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microcopy, X-ray photoelectron spectra and ultraviolet–visible diffuse reflectance spectroscopy. The structure of Bi2S3/MoS2/g-C3N4 is a three-dimensional network structure formed by uniform loading of g-C3N4 and MoS2 around the rod-like Bi2S3 framework. The photodegradation performance was evaluated by the degradation of rhodamine B during irradiation by a 350 W Xe lamp. The degradation rate of Bi2S3/MoS2/g-C3N4 towards rhodamine B reached 95.1% after irradiation for 150[Formula: see text]min. This study will provide new insights into the design of efficient and stable heterostructures for photocatalytic applications.

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