Study of the local structure and oxidation state of iron in complex oxide catalysts for propylene ammoxidation

2014 ◽  
Vol 4 (8) ◽  
pp. 2512-2519 ◽  
Author(s):  
Li-bin Wu ◽  
Liang-hua Wu ◽  
Wei-min Yang ◽  
Anatoly I. Frenkel
Keyword(s):  
Oxidation State ◽  
Local Structure ◽  
Redox Reactions ◽  
Complex Oxide ◽  
Oxide Catalysts ◽  
Visible Spectroscopy ◽  
X Ray ◽  
Propylene Ammoxidation ◽  
Uv Visible ◽  
X Ray Absorption

A combination of X-ray absorption, Raman and UV-visible spectroscopy reveals the competing redox reactions during the deactivation of Fe-based complex catalysts.

Local structure and oxidation state of uranium in some ternary oxides: X-ray absorption analysis

2007 ◽  
Vol 180 (1) ◽  
pp. 54-61 ◽  
Author(s):  
A.V. Soldatov ◽  
D. Lamoen ◽  
M.J. Konstantinović ◽  
S. Van den Berghe ◽  
A.C. Scheinost ◽  
...  
Keyword(s):  
Oxidation State ◽  
Local Structure ◽  
Absorption Analysis ◽  
X Ray ◽  
X Ray Absorption ◽  
Ternary Oxides

scholarly journals Time-Resolved X-ray Absorption Spectroscopy in (Photo)Electrochemistry

Surfaces ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 138-150 ◽  
Author(s):  
Martina Fracchia ◽  
Paolo Ghigna ◽  
Alberto Vertova ◽  
Sandra Rondinini ◽  
Alessandro Minguzzi
Keyword(s):  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Time Resolution ◽  
Local Structure ◽  
Future Perspectives ◽  
Time Resolved ◽  
X Ray ◽  
Fixed Energy ◽  
Complete Survey ◽  
X Ray Absorption

This minireview aims at providing a complete survey concerning the use of X-ray absorption spectroscopy (XAS) for time-resolved studies of electrochemical and photoelectrochemical phenomena. We will see that time resolution can range from the femto-picosecond to the second (or more) scale and that this joins the valuable throughput typical of XAS, which allows for determining the oxidation state of the investigated element, together with its local structure. We will analyze four different techniques that use different approaches to exploit the in real time capabilities of XAS. These are quick-XAS, energy dispersive XAS, pump & probe XAS and fixed-energy X-ray absorption voltammetry. In the conclusions, we will analyze possible future perspectives for these techniques.

scholarly journals Local Structure and Magnetism of LiFeSi0.01P0.99O4/C as a Cathode Material on Lithium-Ion Battery

2021 ◽  
Vol 1 (1) ◽  
pp. 1-4
Author(s):  
Vera Laviara Maghfirohtuzzoimah ◽  
Sahara Hamas Intifadhah ◽  
Pelangi Az-zahra ◽  
Wantana Klysubun ◽  
Dita Puspita Sari ◽  
...  
Keyword(s):  
Lithium Ion Battery ◽  
Oxidation State ◽  
Local Structure ◽  
Lithium Ion ◽  
Antiferromagnetic Order ◽  
Main Peak ◽  
X Ray ◽  
State And Local ◽  
Silicon Doped ◽  
X Ray Absorption

The oxidation state and local structure of LiFeSi0.01P0.99O4/C composites as a cathode on lithium-ion battery were investigated by Fe K-edge X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). The LiFeSi0.01P0.99O4/C sample was prepared by solid-state reaction process. Based on the XANES analysis, the absorption of edge energy (E0) of the sample was 7124.92 eV. In addition, linear combination fitting (LCF) analysis of XANES confirmed the oxidation state of iron mixture of 2+ and 3+ as the effect of silicon doped in LiFePO4. The Fourier Transform (FT) of the Fe K-edge EXAFS fitting analysis showed that the nearest neighbors surrounding atom Fe were the main peak with high intensity that confirmed Fe-O bond; the second and third peak with lower intensity confirmed Fe-P and Fe-Fe bonds, respectively. In addition, the SQUID magnetometer result of LiFeSi0.01P0.99O4/C indicated the antiferromagnetic order temperature of LiFeSi0.01P0.99O4/C at ~51 K with the indication of the presence of impurity and structural distortion.

scholarly journals β-Cyclodextrin-Silica Hybrid: A Spatially Controllable Anchoring Strategy for Cu(II)/Cu(I) Complex Immobilization

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1118
Author(s):  
Federica Calsolaro ◽  
Katia Martina ◽  
Elisa Borfecchia ◽  
Fernando Chávez-Rivas ◽  
Giancarlo Cravotto ◽  
...  
Keyword(s):  
Local Structure ◽  
Redox Properties ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Exhaust Catalysts ◽  
Catalytic Sites ◽  
Hybrid Concept ◽  
Uv Visible ◽  
X Ray Absorption ◽  
New Strategies

The development of new strategies for spatially controllable immobilization has encouraged the preparation of novel catalysts based on the organic-inorganic hybrid concept. In the present paper, a Cu-based multi-structured silica catalyst has been prepared and fully characterized. The inclusion of Cu(II) in β-cyclodextrins has been exploited with the double aim to stabilize the metal and to act as a source of Cu(I) catalytic sites. Multi-technique characterization by infrared, UV-visible, electron microscopy and X-ray absorption spectroscopies of the fresh and exhaust catalysts provided information on the local structure, redox properties and stability of the investigated hybrid systems. The catalytic system showed that copper nanospecies were dispersed on the support and hardly affected by the catalytic tests, confirming the stabilizing effect of β-CD, and likely of the N1-(3-Trimethoxysilylpropyl) diethylenetriamine spacer, as deduced by X-ray absorption spectroscopy analysis. Overall, we demonstrate a feasible approach to efficiently anchor Cu(II) species and to obtain a reusable single-site hybrid catalyst well suited for Cu(I)-catalyzed alkyne-azide cycloaddition.

Biocompatibility of Silver Nano Bio-conjugates from Vitis vinifera Seeds and its Major Component Resveratrol

2016 ◽  
Vol 6 (3) ◽  
Author(s):  
R. Preethi ◽  
P. Padma
Keyword(s):  
Zeta Potential ◽  
Vitis Vinifera ◽  
Silver Ions ◽  
Seed Extract ◽  
Polydispersity Index ◽  
Potential Range ◽  
Visible Spectroscopy ◽  
Grape Seeds ◽  
X Ray ◽  
Uv Visible

The study focused on the green synthesis of silver nanobioconjugates (AgNPs) from phenolic-rich fruit source, Vitis vinifera seed extract and its major component phenolic, resveratrol respectively. Sunlight exposure for 20 minutes was the method of choice for the synthesis of AgNPs of the extract as well as the phenolic, resveratrol. The synthesized nanobioconjugates were characterized using UV-Visible spectroscopy, Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), Polydispersity index, Zeta potential and Fourier transform infrared spectroscopy (FTIR). The reduction of silver ions was confirmed by UV-visible spectroscopy with peaks at 440nm for both nanobioconjugates synthesized from seed extract and compound. The nanobioconjugates showed the spherical in shape with 14-35nm in size and crystalline in nature. The conjugates are well dispersed with 0.301 and 0.287 polydispersity index and the zeta potential range at -13.6 and -14.3mV for stability. The FTRI data proved that the components in grape seeds act as good reductants and stabilizers for the silver nanobioconjugate synthesis. All the synthesized nanobioconjugates exhibited steady and sustained release of the medicinal components conjugated, proving their druggability, and were biocompatible with human cells, demonstrating their safety. The findings of the study validate the anticancer properties of silver nanobioconjugates of Vitis vinifera and its active component resveratrol.

Application of In Situ X-ray Absorption Spectroscopy to Study Dilute Chromium Ions in a Molten Chloride Salt

2019 ◽  
Author(s):  
Jisue Moon ◽  
Carter Abney ◽  
Dmitriy Dolzhnikov ◽  
James M. Kurley ◽  
Kevin A. Beyer ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Local Structure ◽  
Chloride Salt ◽  
X Ray ◽  
Molten Chloride ◽  
Stable Species ◽  
Higher Temperature ◽  
Cr Concentration ◽  
X Ray Absorption

The local structure of dilute CrCl<sub>3</sub> in a molten MgCl<sub>2</sub>:KCl salt was investigated by <i>in situ</i> x-ray absorption spectroscopy (XAS) at temperatures from room temperature to 800<sup>o</sup>C. This constitutes the first experiment where dilute Cr speciation is explored in a molten chloride salt, ostensibly due to the compounding challenges arising from a low Cr concentration in a matrix of heavy absorbers at extreme temperatures. CrCl<sub>3</sub> was confirmed to be the stable species between 200 and 500<sup>o</sup>C, while mobility of metal ions at higher temperature (>700<sup>o</sup>C) prevented confirmation of the local structure.

Evaluation of Antibacterial and Antidiabetic Potential of Silver Nanoparticles using Eugenia Uniflora L. Seed Extract

2020 ◽  
Vol 13 (6) ◽  
pp. 5217-5225
Author(s):  
Guru Kumar Dugganaboyana ◽  
Chethankumar Mukunda ◽  
Suresh Darshini Inakanally
Keyword(s):  
Biomedical Applications ◽  
Pathogenic Bacteria ◽  
Seed Extract ◽  
Drug Formulation ◽  
Visible Spectroscopy ◽  
Plant Materials ◽  
X Ray ◽  
Eugenia Uniflora ◽  
Uv Visible

In recent years, green nanotechnology-based approaches using plant materials have been accepted as an environmentally friendly and cost-effective approach with various biomedical applications. In the current study, AgNPs were synthesized using the seed extract of the Eugenia uniflora L. (E.uniflora). Characterization was done using UV-Visible spectroscopy, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. The formation of AgNPs has confirmed through UV-Visible spectroscopy (at 466 nm) by the change of color owing to surface Plasmon resonance. Based on the XRD pattern, the crystalline property of AgNPs was established. The functional group existing in seed of E.uniflora extract accountable for the reduction of Ag+ ion and the stabilization of AgNPs was investigated. The morphological structures and elemental composition was determined by SEM and EDX analysis. With the growing application of AgNPs in biomedical perspectives, the biosynthesized AgNPs were evaluated for their antibacterial and along with their antidiabetic potential. The results showed that AgNPs are extremely effective with potent antidiabetic potential at a very low concentration. It also exhibited potential antibacterial activity against the three tested human pathogenic bacteria. Overall, the results highlight the effectiveness and potential applications of AgNPs in biomedical fields such as in the treatment of acute illnesses as well as in drug formulation for treating various diseases such as cancer and diabetes. It could be concluded that E. uniflora seed extract AgNPs can be used efficiently for in vitro evaluation of their antibacterial and antidiabetic effects with potent biomedical applications.

scholarly journals Soft x-ray absorption spectroscopy and magnetic circular dichroism as operando probes of complex oxide electrolyte gate transistors

2020 ◽  
Vol 116 (20) ◽  
pp. 201905
Author(s):  
Biqiong Yu ◽  
Guichuan Yu ◽  
Jeff Walter ◽  
Vipul Chaturvedi ◽  
Joseph Gotchnik ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absorption Spectroscopy ◽  
Magnetic Circular Dichroism ◽  
Complex Oxide ◽  
X Ray ◽  
X Ray Absorption ◽  
Circular Dichroïsm ◽  
Oxide Electrolyte

scholarly journals Green synthesis of silk sericin-embedded silver nanoparticles and their antibacterial application against multidrug-resistant pathogens

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Md. Abdullah Al Masud ◽  
Hamid Shaikh ◽  
Md. Shamsul Alam ◽  
M. Minnatul Karim ◽  
M. Abdul Momin ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Bombyx Mori ◽  
Multidrug Resistant ◽  
Visible Spectroscopy ◽  
Silk Sericin ◽  
X Ray ◽  
Synthesis Strategy ◽  
Uv Visible ◽  
Multidrug Resistant Pathogens

Abstract Background The green synthesis strategy of metallic nanoparticles (NPs) has become popular due to being environmentally friendly. Stable silver nanoparticles (AgNPs) have been synthesized by natural products such as starch, soy protein, various extract of leaves, barks, and roots functioning both as reducing and stabilizing agents. Likewise, silk sericin (SS) is a globular protein discarded in the silk factory might be used for NP synthesis. In this research, we focus on the green synthesis and stabilization of AgNPs by SS as well as assessment of their antibacterial activities against some drug-resistant pathogen. Results SS was extracted from Bombyx mori silkworm cocoons in an aqueous medium. 17 w/w% of dry sericin powder with respect to the cocoon’s weight was obtained by freeze-drying. Furthermore, AgNPs conjugated to sericin, i.e., SS-capped silver nanoparticles (SS-AgNPs) were synthesized by easy, cost-effective, and environment-friendly methods. The synthesized SS-AgNPs were characterized by UV-visible spectroscopy, Fourier-transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction measurement. It has been found from the absorbance of UV-visible spectroscopy that a higher percent of SS-AgNPs was obtained at a higher concentration of silver nitrate solution. FTIR-ATR spectra showed that the carboxylate groups obtained from silk sericin act as a reducing agent for the synthesis of silver nanoparticles, while NH2+ and COO− act as a stabilizer of AgNPs. The X-ray diffractogram of SS-AgNPs was quite different from AgNO3 and sericin due to a change in the crystal structure. The diameter of AgNPs was around 20–70 nm observed using TEM. The synthesized SS-AgNPs exhibited strong antibacterial activity against multidrug-resistant pathogens, Escherichia coli and Pseudomonas aeruginosa. Minimal inhibitory/bactericidal concentrations against E. coli and P. aeruginosa were 20μg/mL. Conclusions This study encourages the use of Bombyx mori for the ecofriendly synthesis of SS-AgNPs to control multidrug-resistant microorganisms.

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