3D Imaging of Nickel Oxidation States using Full Field X-ray Absorption Near Edge Structure Nanotomography

This research is aimed to examine oxidation state of Copper (Cu) in both as-synthesized and reduced T’-Pr2-xCexCuO4 (T’-PCCO) with x = 0, 0.10, and 0.15 using Cu K-edge x-ray absorption near edge structure (XANES). The T‘-PCCO nanopowders were successfully synthesized by the chemically dissolved method with HNO3 as a dissolving agent continued by calcination at 1000°C for 15 h. The reduced T’-PCCO nanopowders were obtained by reduction annealing process at 700°C for 5 h under Ar gas atmosphere. The analyses of XANES spectra show that oxidation states of the Cu ions in all of the T'-PCCO nanopowders have values between +1 and +2. This indicates the existence of electron doping in the CuO2 planes, even in the undoped T’-structure. It is found that the oxidation states of the Cu ions change after reduction annealing depending on the existence of apical oxygen in the T'-structure. Based on the XANES analyses, it is revealed that the change of oxidation state is influenced by the presence of both electron and hole carriers in the two-carrier model of T’-structure.

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Solution X-Ray Absorption Spectroscopy (XAS) for Analysis of Catalytically Active Species in Reactions with Ethylene by Homogeneous (Imido)vanadium(V) Complexes—Al Cocatalyst Systems

Catalysts ◽

10.3390/catal9121016 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1016 ◽

Cited By ~ 6

Author(s):

Kotohiro Nomura

Keyword(s):

Active Species ◽

Oxidation States ◽

Donor Ligands ◽

Ethylene Dimerization ◽

Edge Structure ◽

Donor Ligand ◽

X Ray ◽

Catalytically Active ◽

Type V ◽

X Ray Absorption

Solution V K-edge XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) analysis of vanadium(V) complexes containing both imido ligands and anionic ancillary donor ligands (L) of type, V(NR)(L)X2 (R = Ar, Ad (1-adamantyl); Ar = 2,6-Me2C6H3; X = Cl, Me, L = 2-(ArNCH2)C5H4N, OAr, WCA-NHC, and 2-(2’-benzimidazolyl)pyridine; WCA-NHC = anionic NHCs containing weak coordinating B(C6F5)3), which catalyze ethylene dimerization and/or polymerization in the presence of Al cocatalysts, has been explored. Different catalytically actives species with different oxidation states were formed depending upon the Al cocatalyst (MAO, Me2AlCl, AliBu3, etc.) and the anionic ancillary donor ligand employed. The method is useful for obtainment of the direct information of the active species (oxidation state, basic framework around the centered metal) in solution, and for better understanding in catalysis mechanism and organometallic as well as coordination chemistry.

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Application toward Confocal Full-Field Microscopic X-ray Absorption Near Edge Structure Spectroscopy

Analytical Chemistry ◽

10.1021/acs.analchem.6b04828 ◽

2017 ◽

Vol 89 (3) ◽

pp. 2123-2130 ◽

Cited By ~ 2

Author(s):

Pieter Tack ◽

Bart Vekemans ◽

Brecht Laforce ◽

Jennifer Rudloff-Grund ◽

Willinton Y. Hernández ◽

...

Keyword(s):

Edge Structure ◽

Full Field ◽

X Ray ◽

X Ray Absorption

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Full Field Imaging of Nickel Oxidation States in Solid Oxide Fuel Cell Anode Materials by Xanes Nanotomography

ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2011-54947 ◽

2011 ◽

Cited By ~ 1

Author(s):

William M. Harris ◽

George J. Nelson ◽

John R. Izzo ◽

Kyle N. Grew ◽

Wilson K. S. Chiu ◽

...

Keyword(s):

Nickel Oxide ◽

Tomographic Reconstruction ◽

Oxidation States ◽

Edge Structure ◽

Full Field ◽

X Ray ◽

Oxide Phases ◽

The Individual ◽

Cell Anode ◽

Fuel Cell Anode

A greater understanding of nickel reduction-oxidation cycling (redox) mechanisms at the microstructural level can enhance SOFC performance and reliability. Transmission x-ray microscopy (TXM) provides several techniques for exploring oxidation states within SOFC electrode microstructure. X-ray nanotomography and full field x-ray absorption near edge structure (XANES) spectroscopy are new TXM techniques that have been applied in tandem to study samples of varying nickel (Ni) and nickel oxide (NiO) compositions. The imaged samples are treated as mock SOFC anodes containing distinct Ni and NiO regions. XANES spectra for the individual materials provide a basis for the processing and analysis of these mixed samples. Images of composite samples obtained using x-ray nanotomography are treated using numerical image processing steps including: scaling, tomographic reconstruction, and image alignment and subtraction. The distinct nickel and nickel oxide phases have been uniquely identified using full field XANES nanotomography. Applications to SOFC anodes are discussed.

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Vanadium K-edge X-ray-absorption spectroscopy of the functioning and thionine-oxidized forms of the VFe-protein of the vanadium nitrogenase from Azotobacter chroococcum

Biochemical Journal ◽

10.1042/bj2580733 ◽

1989 ◽

Vol 258 (3) ◽

pp. 733-737 ◽

Cited By ~ 35

Author(s):

J M Arber ◽

B R Dobson ◽

R R Eady ◽

S S Hasnain ◽

C D Garner ◽

...

Keyword(s):

Absorption Spectra ◽

Absorption Spectroscopy ◽

Azotobacter Chroococcum ◽

Vanadium Atom ◽

Oxidation States ◽

Edge Structure ◽

X Ray ◽

Vanadium Nitrogenase ◽

Enzyme Turnover ◽

X Ray Absorption

Vanadium K-edge X-ray-absorption spectra were collected for samples of thionine-oxidized, super-reduced (during enzyme turnover) and dithionite-reduced VFe-protein of the vanadium nitrogenase of Azotobacter chroococcum (Acl*). Both the e.x.a.f.s and the x.a.n.e.s. (X-ray-absorption near-edge structure) are consistent with the vanadium being present as part of a VFeS cluster; the environment of the vanadium is not changed significantly in different oxidation states of the protein. The vanadium atom is bound to three oxygen (or nitrogen), three sulphur and three iron atoms at 0.215(3), 0.231(3) and 0.275(3) nm respectively.

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A compact furnace for in situ X-ray absorption spectroscopy: design, fabrication and study of cationic oxidation states in Pr6O11 and NiO

Journal of Synchrotron Radiation ◽

10.1107/s1600577520015696 ◽

2021 ◽

Vol 28 (2) ◽

pp. 455-460

Author(s):

Suchinda Sattayaporn ◽

Somboonsup Rodporn ◽

Pinit Kidkhunthod ◽

Narong Chanlek ◽

Chutarat Yonchai ◽

...

Keyword(s):

Oxidation State ◽

Absorption Spectroscopy ◽

Heating Temperature ◽

Reduction Process ◽

Oxidation States ◽

Quartz Tube ◽

Edge Structure ◽

X Ray ◽

X Ray Absorption

A well designed compact furnace has been designed for in situ X-ray absorption spectroscopy (XAS). It enables various heat ramps from 300 K to 1473 K. The furnace consists of heaters, a quartz tube, a circulated refrigerator and a power controller. It can generate ohmic heating via an induction process with tantalum filaments. The maximum heating rate exceeds 20 K min−1. A quartz tube with gas feedthroughs allows the mixing of gases and adjustment of the flow rate. The use of this compact furnace allows in situ XAS investigations to be carried out in transmission or fluorescence modes under controlled temperature and atmosphere. Moreover, the furnace is compact, light and well compatible to XAS. The furnace was used to study cationic oxidation states in Pr6O11 and NiO compounds under elevated temperature and reduced atmosphere using the in situ X-ray absorption near-edge structure (XANES) technique at beamline 5.2 SUT-NANOTEC-SLRI of the Synchrotron Light Research Institute, Thailand. At room temperature, Pr6O11 contains a mixture of Pr3+ and Pr4+ cations, resulting in an average oxidation state of +3.67. In situ XANES spectra of Pr (L 3-edge) show that the oxidation state of Pr4+ cations was totally reduced to +3.00 at 1273 K under H2 atmosphere. Considering NiO, Ni2+ species were present under ambient conditions. At 573 K, the reduction process of Ni2+ occurred. The Ni0/Ni2+ ratio increased linearly with respect to the heating temperature. Finally, the reduction process of Ni2+ was completely finished at 770 K.

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