In this paper we study of the local atomic and electronic structure of nanostructured condensed material for rechargeable current sources on the basis of 15mas.%V2O5/Fe/LiF nanocomposite within charge-discharge cycle. Principle component analysis (PCA) of the series of Fe K-edge spectra collected during 1 st charge showing the concentrations of the components Fe, FeF2 and V[FeV]O4. We found the changes in the V oxidation state from the analysis of the experimental Fe K- and V K- XANES spectra. Total and partial density of states of components are presented.
Keywords: nanostructured materials for rechargeable current sources, dynamics of local atomic and electronic structures, XANES, DFT
In the present work we report on the study of local atomic and electronic structure of gold nanoparticles funnctionalised by thiol and amine containing long-chain ligands. The study of nanoscale atomic structure is performed by means of X-ray absorption spectroscopy (XANES: X-ray Absorption Near-Edge Structure) and computer simulation. In consequence of the experimantally obtained data analysis and computer simulation it was obtained that strong bonding takes place when 11-mercaptoundecanoic acid is bound to the gold nanoparticles surface, forming a chemical bond Au-S 0.25 nm in length. Weaker bonding is observed when forming bond between dodecylamine and gold nanoparticles surface atom resulting in Au-N bond 0.23 nm in length. Supplementary XANES spectra analysis by means of density functional theory reveals the nature of formation of the investigated nanoscale structure.
Keywords: nanoscale structure of matter, X-ray absorption spectroscopy, XANES, density functional theory, nanoparticles functionalisation
The nano-catalyst ceria (CeO2), activated by Pt nanoparticles, is known for being prospective and efficient material widely used in catalysis, fuel elements, and sensors. One of the most up-to-date methods of catalysts' reasearch is X-ray absorption spectroscopy (XAS) that is sensitive to the chemical state of catalyst's active centers [1,2]. Using XAS in the fluorescense detection mode at CeL1 line with high precision we studied electronic structure of Pt-activated nanoparticles of ceria at various redox conditions. In order to detect partial X-ray fluorescence yield the emission line CeLγ3 was used, which allowed us to increase spectral resolution. We researched local atomic and electronic structure of the materials under study. Oxygen vacansies were found to appear on the nanoparticles surface of ceria at 5% CO He atmosphere. Theoretical modeling of the obtained spectra at CeL1-edge demonstrated good agreement with experiment.
Keywords: X-ray absorption spectroscopy, HERFD, XAS, Ce-based catalysts, oxygen vacansies
This paper describes an in-situ experimental technique to study of ceria nanocatalysts by using X-ray absorption near edge spectroscopy XANES. This technique allows us to determine Ce3+ concentration inside ceria nanoparticles in the course of catalytic reaction based on the comparison and divergence minimization of the Ce L3 XANES spectrum of the ceria nanoparticles under catalysts (atmosphere, temperature) with a linear combination of two independent components corresponding to spectra of Ce4+ ion of the CeO2 structure and Ce3+ ion of the theoretical Ce2O3 structure. The calculated weight ratio determines the Ce3 + concentration in the sample during the catalytic reactions.
Keywords: in-situ X-ray absorption spectroscopy, HERFD, XAS, ceria nanoparticles, Ce-based catalysts, Ce3+ concentration
In this paper we study the dynamics of the local atomic structure of new nanostructured condensed material for for rechargeable current sources on the basis of 15mas.%V2O5/Fe/LiF nanocomposite within charge-discharge cycle on the basis of X-ray diffraction (XRD), X-ray absorption spectroscopy (XANES) and of computer simulation. The analysis of the experimental data obtained during the first charge cycle reveals the transformation of iron to more than 50% of iron fluoride (II) , Li ions intercalate into the structure of amorphous V2O5 forming LiVO2 compound.
Keywords: diversification of management, production diversification, financial and economic purposes of a diversification, technological purposes of ensuring flexibility of production
Combined method which allows analyzing parameters of the nanoscale atomic and electronic structure of materials relying on three different methods (x-ray absorption spectroscopy (XAFS), x-ray diffraction (XRD) and Raman spectroscopy) was developed. The method was applied for the study of nickel oxide nanoparticles, which serve as an efficient catalyst for the artificial photosynthesis process.
Keywords: solar energy, artificial photosynthesis, NiO, Raman, x-ray diffraction, XAFS
We have carried out the analysis on the scientific and technological literature on methods of calculation and analysis of the x-ray diffraction, x-ray absorption and Raman spectra used to analyse the structure of the materials for hydrogen storage under realistic operating conditions. The simulations were carried out for the series of small palladium nanoclusters with embedded hydrogen. Multiscale computer modelling was used to simulate the dynamics of structure of the materials during charge/discharge phases.
Keywords: hydrogen storage, XANES, x-ray diffraction, Raman scattering, fuel cell