scholarly journals Hydrogenation of terminal and internal olefins using a biowaste-derived heterogeneous cobalt catalyst

2018 ◽  
Vol 4 (9) ◽  
pp. eaau1248 ◽  
Author(s):  
Florian Korbinian Scharnagl ◽  
Maximilian Franz Hertrich ◽  
Francesco Ferretti ◽  
Carsten Kreyenschulte ◽  
Henrik Lund ◽  
...  
Keyword(s):  
Magnetic Behavior ◽  
Magnetic Composite ◽  
Metal Composite ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Water As Solvent ◽  
Scanning Transmission ◽  
Product Separation ◽  
Electron Energy Loss

Hydrogenation of olefins is achieved using biowaste-derived cobalt chitosan catalysts. Characterization of the optimal Co@Chitosan-700 by STEM (scanning transmission electron microscopy), EELS (electron energy loss spectroscopy), PXRD (powder x-ray diffraction), and elemental analysis revealed the formation of a distinctive magnetic composite material with high metallic Co content. The general performance of this catalyst is demonstrated in the hydrogenation of 50 olefins including terminal, internal, and functionalized derivatives, as well as renewables. Using this nonnoble metal composite, hydrogenation of terminal C==C double bonds occurs under very mild and benign conditions (water or methanol, 40° to 60°C). The utility of Co@Chitosan-700 is showcased for efficient hydrogenation of the industrially relevant examples diisobutene, fatty acids, and their triglycerides. Because of the magnetic behavior of this material and water as solvent, product separation and recycling of the catalyst are straightforward.

Solvothermal synthesis and characterization of well-dispersed cerium-doped Y2SiO5 phosphor particles

2021 ◽  
Vol 112 (10) ◽  
pp. 812-816
Author(s):  
Xianxue Li
Keyword(s):  
Solvothermal Method ◽  
Luminescence Decay ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fluorescence Spectrophotometry ◽  
Decay Properties ◽  
Transmission Electron ◽  
Water As Solvent ◽  
Pure Phase

Abstract Well-dispersed cerium-doped Y2SiO5 (Ce:YSO) phosphor particles with spherical morphology and good luminescence intensity have been achieved by a solvothermal method with ethanol and water as solvent media. X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectrophotometry and transmission electron microscopy were employed to characterize the as-synthesized Ce:YSO precursor and powders. The results showed that pure-phase Ce:YSO powders with a mean particle size of about 162 nm were accurately available at 310°C and above. The fluorescence ability and persistent luminescence decay properties of the Ce:YSO powders were also studied, and the excellent fluorescence properties could be attributed to the homogeneous Ce:YSO particles obtained through the solvothermal method.

scholarly journals Growth and characterization of CNT–TiO2 heterostructures

2014 ◽  
Vol 5 ◽  
pp. 946-955 ◽  
Author(s):  
Yucheng Zhang ◽  
Ivo Utke ◽  
Johann Michler ◽  
Gabriele Ilari ◽  
Marta D Rossell ◽  
...  
Keyword(s):  
Good Control ◽  
Atomic Layer ◽  
Oxide Material ◽  
Electronic Information ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Metal Metal ◽  
Scanning Transmission ◽  
Electron Energy Loss

A thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking full advantages of unique properties of each component. In this context, combining TiO2 nanocrystals and carbon nanotubes (CNTs) offers enhanced photosensitivity and improved photocatalytic efficiency, which is key to achieving sustainable energy and preventing environmental pollution. Hence, it has aroused a tremendous research interest. This report surveys recent research on the topic of synthesis and characterization of the CNT–TiO2 interface. In particular, atomic layer deposition (ALD) offers a good control of the size, crystallinity and morphology of TiO2 on CNTs. Analytical transmission electron microscopy (TEM) techniques such as electron energy loss spectroscopy (EELS) in scanning transmission mode provides structural, chemical and electronic information with an unprecedented spatial resolution and increasingly superior energy resolution, and hence is a necessary tool to characterize the CNT–TiO2 interface, as well as other technologically relevant CNT–metal/metal oxide material systems.

scholarly journals Structural characterization of Fe–C coatings prepared by reactive triode-magnetron sputtering

2010 ◽  
Vol 25 (9) ◽  
pp. 1859-1869 ◽  
Author(s):  
Isabelle Jouanny ◽  
Valérie Demange ◽  
Jaafar Ghanbaja ◽  
Elisabeth Bauer-Grosse
Keyword(s):  
Magnetron Sputtering ◽  
Gas Flow ◽  
Carbon Matrix ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Electron Energy Loss

Fe1–xCx coatings were synthesized by triode magnetron sputtering of an iron target in a methane/argon atmosphere with a large range of composition (x = 0.3 to 0.6 ± 0.06). Film surfaces were characterized by grazing incidence x-ray diffraction, scanning and transmission electron microscopies, and electron energy loss spectroscopy, to study effects of the variation of the methane gas flow rate on their structural properties. The coatings were constituted of the ε-Fe3C carbide (x = 0.3 and 0.36), in which carbon atoms are in octahedral sites, and of nanocomposite structure constituted of disordered and crystalline carbide nanograins embedded in a carbon matrix made of an amorphous and poorly crystallized graphenelike material (x = 0.55 and 0.60). In situ annealing of the nanocomposite Fe0.45C0.55 coating led to the formation of carbides θ-Fe3C and Fe7C3 (with carbon atoms in prismatic sites) and C-rich cubic carbide possibly related to the τ2-Fe2C7 compound.

Characterization of Shell Material on Colloidal CdSe/ZnS Quantum Dots

2004 ◽  
Vol 818 ◽  
Author(s):  
Zhiheng Yu ◽  
Li Guo ◽  
Hui Du ◽  
Todd Krauss ◽  
John Silcox
Keyword(s):  
Quantum Dots ◽  
Surface Passivation ◽  
Core Shell ◽  
Shell Material ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Chemical Distribution ◽  
Electron Energy Loss

AbstractScanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) was used to determine the distribution of ZnS shell material on colloidal core-shell CdSe/ZnS quantum dots (QDs). A sub-nm electron probe was placed at various locations on core-shell QDs to ascertain the chemical distribution of the shell material. While a definite shell of ZnS was detected surrounding the CdSe core, the integrated EELS signals from positions around the QD suggest the distribution of the shell material may not be uniform. A non-uniform shell implies a reduced quality of the QD surface passivation.

scholarly journals Mechanical Characterization of Cryomilled Al Powder Consolidated by High-Frequency Induction Heat Sintering

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Ehab A. El-Danaf ◽  
Mahmoud S. Soliman ◽  
Abdulhakim A. Almajid ◽  
Khalil Abdelrazek Khalil
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
High Frequency ◽  
X Ray Diffraction ◽  
Induction Heat ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Thermal Stability Of ◽  
High Frequency Induction

In the present investigation, an aluminum powder of 99.7% purity with particle size of ~45 µm was cryomilled for 7 hours. The produced powder as characterized by scanning, transmission electron microscopy, and X-ray diffraction gave a particle size of ~1 µm and grain (crystallite) size of23±6 nm. This powder, after degassing process, was consolidated using high-frequency induction heat sintering (HFIHS) at various temperatures for short periods of time of 1 to 3 minutes. The present sintering conditions resulted in solid compact with nanoscale grain size (<100 nm) and high compact density. The mechanical properties of a sample sintered at 773 K for 3 minutes gave a compressive yield and ultimate strength of 270 and 390 MPa, respectively. The thermal stability of grain size nanostructured compacts is in agreement with the kinetics models based on the thermodynamics effects.

scholarly journals Sodium-Vanadium Bronze Na9V14O35: An Electrode Material for Na-Ion Batteries

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 86
Author(s):  
Maria A. Kirsanova ◽  
Alexey S. Akmaev ◽  
Mikhail V. Gorbunov ◽  
Daria Mikhailova ◽  
Artem M. Abakumov
Keyword(s):  
Negative Electrode ◽  
X Ray Diffraction ◽  
Conversion Reaction ◽  
X Ray ◽  
Electroactive Material ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electrochemical Capacity ◽  
Silica Ampoule ◽  
Electron Energy Loss

Na9V14O35 (η-NaxV2O5) has been synthesized via solid-state reaction in an evacuated sealed silica ampoule and tested as electroactive material for Na-ion batteries. According to powder X-ray diffraction, electron diffraction and atomic resolution scanning transmission electron microscopy, Na9V14O35 adopts a monoclinic structure consisting of layers of corner- and edge-sharing VO5 tetragonal pyramids and VO4 tetrahedra with Na cations positioned between the layers, and can be considered as sodium vanadium(IV,V) oxovanadate Na9V104.1+O19(V5+O4)4. Behavior of Na9V14O35 as a positive and negative electrode in Na half-cells was investigated by galvanostatic cycling against metallic Na, synchrotron powder X-ray diffraction and electron energy loss spectroscopy. Being charged to 4.6 V vs. Na+/Na, almost 3 Na can be extracted per Na9V14O35 formula, resulting in electrochemical capacity of ~60 mAh g−1. Upon discharge below 1 V, Na9V14O35 uptakes sodium up to Na:V = 1:1 ratio that is accompanied by drastic elongation of the separation between the layers of the VO4 tetrahedra and VO5 tetragonal pyramids and volume increase of about 31%. Below 0.25 V, the ordered layered Na9V14O35 structure transforms into a rock-salt type disordered structure and ultimately into amorphous products of a conversion reaction at 0.1 V. The discharge capacity of 490 mAh g−1 delivered at first cycle due to the conversion reaction fades with the number of charge-discharge cycles.

scholarly journals Obtaining and Characterization of TiO2-GO Composites for Photocatalytic Applications

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
D. K. Calvo Ramos ◽  
M. Vega González ◽  
R. A. Esparza Muñóz ◽  
J. Santos Cruz ◽  
F. J. De Moure-Flores ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Uv Radiation ◽  
Uv Light ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

Titanium dioxide (TD) and graphene oxide (GO) were synthesized by sol-gel and improved Hummers method, respectively. This study shows the results of the incorporation through four different conditions (sol-gel, sol-gel and ultrasonic, annealed, and UV radiation, C1 to C4, respectively). It was observed that a homogeneous incorporation of TD on sheets of GO was obtained satisfactorily. The composites of TiO2/GO were characterized using different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and infrared spectroscopy (IR). The photocatalytic activity of the composites was determined from the degradation of the dye azo tartrazine using UV and solar radiation. The best incorporation of TD nanoparticles on GO was obtained with condition C3 (thermal incorporation method) at a temperature of 65°C. This shows a uniformity in the size and shape of the TD as well as an excellent adherence to the sheet of GO. This addition is accomplished by ionic bonding in the presence of electrostatic Coulomb forces. The C3 composite degraded the tartrazine dye using UV radiation and sunlight. With the latter, the degradation time was three times faster than using UV light.

Sign in / Sign up

Export Citation Format

Share Document