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

  Stability of sensors on the basis of inorganic oxide materials is one of the primary goals by working out of atmospheric air control devices. In this work long-term stability of a sensor response on the basis of the SiO2SnOxCuOy material to carbon oxide (II) exposure in a range of concentration 1-100 ppm is studied. It is shown that the sensor response differs high stability and reproducibility. Continuous heating within 21 days to working temperature (350°С) influence its value negligibly.

Keywords: stability of a response, sensor, carbon oxide, material of structure of SiO2SnOxCuOy.