scholarly journals Morphological analysis of cerium oxide stabilized nanoporous gold catalysts by soft X-ray ASAXS

RSC Advances ◽  
2017 ◽  
Vol 7 (72) ◽  
pp. 45344-45350 ◽  
Author(s):  
C. Rumancev ◽  
A. R. von Gundlach ◽  
S. Baier ◽  
A. Wittstock ◽  
J. Shi ◽  
...  
Keyword(s):  
Cerium Oxide ◽  
Morphological Analysis ◽  
Morphological Changes ◽  
Gold Catalyst ◽  
Gold Catalysts ◽  
Nanoporous Gold ◽  
Morphological Properties ◽  
X Ray ◽  
Stabilizing Effect

Soft X-ray SAXS and ASAXS reveal nanostructural properties and temperature induced morphological changes in catalyst materials. The stabilizing effect of cerium oxide deposits on the gold catalyst and the morphological properties of the cerium oxide were determined.

scholarly journals Correlative Multiscale 3D Imaging of a Hierarchical Nanoporous Gold Catalyst by Electron, Ion and X-ray Nanotomography

ChemCatChem ◽  
2018 ◽  
Vol 10 (13) ◽  
pp. 2858-2867 ◽  
Author(s):  
Yakub Fam ◽  
Thomas L. Sheppard ◽  
Ana Diaz ◽  
Torsten Scherer ◽  
Mirko Holler ◽  
...  
Keyword(s):  
3D Imaging ◽  
Gold Catalyst ◽  
Nanoporous Gold ◽  
X Ray

Preparation of Layered Double Hydroxide (LDHs)-Supported Gold Catalysts and its Activity and Stability for Low-Temperature CO Oxidation

2011 ◽  
Vol 396-398 ◽  
pp. 841-847
Author(s):  
Peng Wang ◽  
Lin Hua Zhu
Keyword(s):  
Thermal Treatment ◽  
Room Temperature ◽  
Ph Value ◽  
Gold Catalyst ◽  
Gold Catalysts ◽  
Oxidation Activity ◽  
Gold Colloids ◽  
Gold Particles ◽  
X Ray ◽  
Double Hydroxide

A new type of gold catalysts have been prepared by supporting gold colloids on layered double hydroxide (MgAl-LDHs) carrier at different pH values. CO oxidation reaction at room temperature was used as probe reaction to test the oxidation activity of the gold catalysts, and X-ray diffraction (XRD), X-ray fluorescence (XRF) and high resolution transmission election microscopy (HRTEM) techniques were used to characterize the physical phase, gold loading, morphology as well as mean diameter of gold particles and particle distribution of the represented gold catalyst samples. Influence of pH value during synthesis of the catalysts on the gold loading and oxidation activity of the gold catalysts was studied. Besides these, the stability of the gold catalysts was investigated by thermal treatment and exposure to air and natural light for a long time. The results indicated that gold colloids can be attached on the carrier easily when pH value was controlled between 6-7, and gold loading in the gold catalysts prepared in this condition was above 1.3wt.%. 100% conversion of CO at room temperature can be obtained when the fresh prepared catalysts had been calcined in the air for 2 h at 473 K. The HRTEM images of the gold catalyst showed that the gold particles were highly dispersed on the surface of the carrier, and the average size of the gold particles was 3.2 nm. After thermal treatment at 723 K or storage 4 weeks in air, gold particle size was still kept less than 5nm and the conversion of CO at room temperature over the aged catalysts achieved 100%.

scholarly journals Efficient Synthesis of Methyl Methacrylate by One Step Oxidative Esterification over Zn-Al-Mixed Oxides Supported Gold Nanocatalysts

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 162
Author(s):  
Huayin Li ◽  
Yuan Tan ◽  
Xingkun Chen ◽  
Wenshao Yang ◽  
Chuanqi Huang ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Mixed Oxides ◽  
Gold Catalyst ◽  
Co Adsorption ◽  
Gold Catalysts ◽  
Esterification Reaction ◽  
X Ray ◽  
Oxidative Esterification ◽  
One Step ◽  
Supported Gold

Methyl methacrylate (MMA) is an important monomer in fine chemicals. The synthesis of MMA by one-step oxidative esterification from methacrolein with methanol over a heterogeneous catalyst with high activity, selectivity and stability is highly desirable. Herein, Zn-Al-hydrotalcites (HTs)-supported atomically precise Au25 nanoclusters with different molar ratios of Zn2+/Al3+ were prepared and used as the precursors for this reaction. They exhibited good performances in comparison with the gold catalysts prepared by the deposition precipitation method. The structural and electronic properties were evaluated by various characterization technologies, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) of CO adsorption, X-ray photoelectron spectroscopy (XPS), and CO2 temperature-programmed desorption (TPD). The combined characterization results suggested that the adsorption property of gold and the basicity of the catalyst contributes to their high activities. Substrates extended experiments and stability tests implied the potential application of Zn-Al-mixed oxides supported gold catalysts, which paves a new way for supported gold catalyst in the one-step oxidation esterification reaction.

scholarly journals Thermal Stability of Oxide-Based Solar Selective Coatings for CSP Central Receivers

2015 ◽  
Author(s):  
Andrea Ambrosini ◽  
Timothy N. Lambert ◽  
Antoine Boubault ◽  
Andrew Hunt ◽  
Danae J. Davis ◽  
...  
Keyword(s):  
Optical Properties ◽  
Morphological Changes ◽  
Morphological Properties ◽  
Inconel 625 ◽  
X Ray Diffraction ◽  
Haynes 230 ◽  
X Ray ◽  
Ni Alloys ◽  
Sprayed Coating ◽  
Thermal Stability Of

Efforts at Sandia National Laboratories are addressing more efficient solar selective coatings for tower applications, based on oxide materials deposited by a variety of methods. Over the course of this investigation, several compositions with optical properties competitive to Pyromark have been identified. These promising coatings were deposited on Inconel 625 and Haynes 230 Ni alloys and isothermally aged in air at temperatures between 600–800 °C for up to 480 hours, concurrently with Pyromark®, which was used as a reference standard. At various heating times, the samples were removed from the furnace and their optical properties (solar-weighted absorptance and emittance) were measured. In addition, x-ray diffraction and scanning electron microscopy were utilized to investigate any structural or morphological changes that occurred over time with heating, in an attempt to correlate with changes in optical properties. At 600 and 700 °C, several of the coatings maintained an absorptivity > 90%. While the chemical makeup of the coating material greatly influences its optical properties, the morphology of the surface also plays in important part. A thermal sprayed coating modified using a novel laser treatment showed improved properties versus the untreated coating, on par with Pyromark™ at 600 °C, with little degradation after 480 hours. The results of aging on the optical, structural, and morphological properties of these novel coatings will be discussed.

scholarly journals γ-Rays Irradiation Induced Structural and Morphological Changes in Copper Nanowires

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
H. Shehla ◽  
F. T. Thema ◽  
A. Ishaq ◽  
Naveed Zafar Ali ◽  
I. Javed ◽  
...  
Keyword(s):  
Thin Film ◽  
Morphological Changes ◽  
High Energy ◽  
Morphological Properties ◽  
Copper Nanowires ◽  
X Ray Diffraction ◽  
Covalent Bonds ◽  
X Ray ◽  
Γ Rays ◽  
Cu Thin Film

This contribution reports on the effect ofγ-irradiations on the structural and morphological properties of copper nanowires (Cu-NWs) within theγdoses varying from 6 to 25 kGy. At 9 kGy, the Cu-NWs started welding, forming perfect X-, V-, II-, and Y-shaped molecular junctions. Further increasing theγdose up to 15 kGy caused the Cu-NWs to fuse and form larger diameter NWs. At the highest dose of 25 kGy, the nanowires converted into a continuous Cu thin film. However, X-ray diffraction (XRD) results showed that the structure of the Cu-NWs remained stable even after converting into a thin film. The formation of the Cuprite (Cu2O) phases was observed at higherγdose. The mechanism of forming welded networks of Cu-NWs and Cu thin films is explained via the short and high energyγ-ray wavelengths which act on Cu-Cu molecular covalent bonds isotropically.

Appraisal of innovative phytosynthetic CdO NPs from leaf extract of Ocimum Sanctum and their bactericidal activity against different strains

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Aarth R ◽  
Sudha A P ◽  
Sujatha B ◽  
Sowmya Lakshmi K
Keyword(s):  
Leaf Extract ◽  
Cadmium Oxide ◽  
Morphological Properties ◽  
Precipitation Method ◽  
Ocimum Sanctum ◽  
Oxide Nanoparticles ◽  
Average Crystalline Size ◽  
Face Centered Cubic ◽  
Bacterial Strains ◽  
X Ray

The phytosynthesis of n-type Cadmium Oxide Nanoparticles reduces the toxicity of the substance and makes it Eco-friendly. This Eco-friendly biosynthesis of CdO NPs was synthesized for the first time from the Queen of herbs, Ocimum Sanctum (holy basil).The biosynthesized Cadmium oxide was prepared using Ocimum leaf extract as a reductant and Cadmium Chloride and hydroxide as cadmium and oxide source materials by Co- Precipitation method. Thus obtained Cadmium Oxide Nanoparticles were characterized by different techniques such as X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM),Energy dispersive X-ray spectroscopy(EDS) to study the structural and morphological properties. XRD pattern exhibited the formation of face centered cubic structure of CdO NPs with an average crystalline size of 11.5nm .The chemical bond formation of CdO NPs were confirmed by FTIR spectrum in the range of (400-4000cm-1). The SEM micrographs revealed the predominant formation of Cauliflower shape with a particle size in the range of 61-142nm. The high purity of the biosynthesized nanoparticles were confirmed by EDS analysis. Further it was tested against gram positive and gram negative bacterial strains and showed significant antibacterial activity. This biosynthetic research study opens an innovative window to progress our understanding of how CdO NPs shows resistance to different bacterial strains.

scholarly journals Nano- scale X-ray Computed Tomography: Morphological Analysis of Fuel Cell Electrodes

2013 ◽  
Vol 19 (S2) ◽  
pp. 630-631
Author(s):  
P. Mandal ◽  
W.K. Epting ◽  
S. Litster
Keyword(s):  
Computed Tomography ◽  
Fuel Cell ◽  
Morphological Analysis ◽  
Fuel Cell Electrodes ◽  
X Ray ◽  
Nano Scale ◽  
X Ray Computed

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

scholarly journals Functional Attributes of Myco-Synthesized Silver Nanoparticles from Endophytic Fungi: A New Implication in Biomedical Applications

Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 473
Author(s):  
Prabu Kumar Seetharaman ◽  
Rajkuberan Chandrasekaran ◽  
Rajiv Periakaruppan ◽  
Sathishkumar Gnanasekar ◽  
Sivaramakrishnan Sivaperumal ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Culture Filtrate ◽  
Morphological Changes ◽  
Xrd Analysis ◽  
Penicillium Oxalicum ◽  
Breast Cancer Cell Lines ◽  
Face Centered Cubic ◽  
Tem Analysis ◽  
X Ray ◽  
Average Size

To develop a benign nanomaterial from biogenic sources, we have attempted to formulate and fabricate silver nanoparticles synthesized from the culture filtrate of an endophytic fungus Penicillium oxalicum strain LA-1 (PoAgNPs). The synthesized PoAgNPs were exclusively characterized through UV–vis absorption spectroscopy, Fourier Transform Infra-Red spectroscopy (FT-IR), X-ray powder diffraction (XRD), and Transmission Electron Microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX). The synthesized nanoparticles showed strong absorbance around 430 nm with surface plasmon resonance (SPR) and exhibited a face-centered cubic crystalline nature in XRD analysis. Proteins presented in the culture filtrate acted as reducing, capping, and stabilization agents to form PoAgNPs. TEM analysis revealed the generation of polydispersed spherical PoAgNPs with an average size of 52.26 nm. The PoAgNPs showed excellent antibacterial activity against bacterial pathogens. The PoAgNPs induced a dose-dependent cytotoxic activity against human adenocarcinoma breast cancer cell lines (MDA-MB-231), and apoptotic morphological changes were observed by dual staining. Additionally, PoAgNPs demonstrated better larvicidal activity against the larvae of Culex quinquefasciatus. Moreover, the hemolytic test indicated that the as-synthesized PoAgNPs are a safe and biocompatible nanomaterial with versatile bio-applications.

scholarly journals X-ray Shielding, Mechanical, Physical, and Water Absorption Properties of Wood/PVC Composites Containing Bismuth Oxide

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2212
Author(s):  
Worawat Poltabtim ◽  
Ekachai Wimolmala ◽  
Teerasak Markpin ◽  
Narongrit Sombatsompop ◽  
Vichai Rosarpitak ◽  
...  
Keyword(s):  
Impact Strength ◽  
Water Absorption ◽  
Attenuation Coefficient ◽  
Bismuth Oxide ◽  
Morphological Properties ◽  
Linear Attenuation Coefficient ◽  
X Rays ◽  
Equivalent Thickness ◽  
X Ray ◽  
The Impact

The potential utilization of wood/polyvinyl chloride (WPVC) composites containing an X-ray protective filler, namely bismuth oxide (Bi2O3) particles, was investigated as novel, safe, and environmentally friendly X-ray shielding materials. The wood and Bi2O3 contents used in this work varied from 20 to 40 parts per hundred parts of PVC by weight (pph) and from 0 to 25, 50, 75, and 100 pph, respectively. The study considered X-ray shielding, mechanical, density, water absorption, and morphological properties. The results showed that the overall X-ray shielding parameters, namely the linear attenuation coefficient (µ), mass attenuation coefficient (µm), and lead equivalent thickness (Pbeq), of the WPVC composites increased with increasing Bi2O3 contents but slightly decreased at higher wood contents (40 pph). Furthermore, comparative Pbeq values between the wood/PVC composites and similar commercial X-ray shielding boards indicated that the recommended Bi2O3 contents for the 20 pph (40 ph) wood/PVC composites were 35, 85, and 40 pph (40, 100, and 45 pph) for the attenuation of 60, 100, and 150-kV X-rays, respectively. In addition, the increased Bi2O3 contents in the WPVC composites enhanced the Izod impact strength, hardness (Shore D), and density, but reduced water absorption. On the other hand, the increased wood contents increased the impact strength, hardness (Shore D), and water absorption but lowered the density of the composites. The overall results suggested that the developed WPVC composites had great potential to be used as effective X-ray shielding materials with Bi2O3 acting as a suitable X-ray protective filler.

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