Jump to main content
Jump to site search

Issue 69, 2016, Issue in Progress
Previous Article Next Article

Structural, physical and chemical properties of nanostructured nickel-substituted ceria oxides under reducing and oxidizing conditions

Author affiliations

Abstract

This work reports the synthesis of nanostructured Ce1−xNixO2−δ (x = 0.05, 0.1, 0.15 and 0.2) oxides prepared by a cation complexation route and with the main objective of studying their redox properties using a combination of electron microscopy, synchrotron radiation X-ray diffraction (SR-XRD) and X-ray absorption near-edge spectroscopy (XANES). The Ce1−xNixO2−δ series of nanopowders maintain the cubic crystal structure (Fm3m space group) of pure ceria, with an average crystallite size of 5–7 nm indicated by XRD patterns and confirmed by transmission electron microscopy. In situ SR-XRD and XANES carried out under reducing (5% H2/He; 5% CO/He) and oxidizing (21% O2/N2) atmospheres at temperatures up to 500 °C show a Ni solubility limit close to 15 at% in air at room temperature, decreasing to about 10 at% after exposure to 5% H2/He atmosphere at 500 °C. At room temperature in air, the effect of Ni on the lattice parameter of Ce1−xNixO2−δ is negligible, whereas a marked expansion of the lattice is observed at 500 °C in reducing conditions. This is shown by XANES to be correlated with the reduction of up to 25% of Ce4+ cations to the much larger Ce3+, possibly accompanied by the formation of oxygen vacancies. The redox ability of the Ce4+/Ce3+ couple in nanocrystalline Ni-substituted ceria is greatly enhanced in comparison to pure ceria or achieved by using other dopants (e.g. Gd, Tb or Pr), where it is limited to less than 5% of Ce cations.

Graphical abstract: Structural, physical and chemical properties of nanostructured nickel-substituted ceria oxides under reducing and oxidizing conditions

Back to tab navigation

Supplementary files

Publication details

The article was received on 08 Jun 2016, accepted on 02 Jul 2016 and first published on 04 Jul 2016


Article type: Paper
DOI: 10.1039/C6RA14853K
Author version
available:
Download author version (PDF)
Citation: RSC Adv., 2016,6, 64861-64870
  •   Request permissions

    Structural, physical and chemical properties of nanostructured nickel-substituted ceria oxides under reducing and oxidizing conditions

    R. O. Fuentes, L. M. Acuña, C. A. Albornoz, A. G. Leyva, N. Sousa and F. M. Figueiredo, RSC Adv., 2016, 6, 64861
    DOI: 10.1039/C6RA14853K

Search articles by author

Spotlight

Advertisements