Abstract
Nanocrystalline (4–5nm) Ce1−xRuxO2 mixed oxides (x=0.03–0.16) were synthesized using water in oil microemulsion method. Morphology, microstructure and a phase composition of the samples subjected to heat treatment in oxidizing and reducing atmosphere were investigated by TEM, SEM-EDS-EBSD, XRD and XPS. Oxide with x=0.11 was structurally stable in oxidizing atmosphere up to 550°C but above this temperature it decomposed into Ru deficient, nanosized Ce1−xRuxO2 and large (few μm) RuO2 crystals. No phase separation was observed for Ce0.97Ru0.03O2 even after heating at 800°C. Doping with Ru decreases the size of ceria particles and strongly hinders their sintering at high temperatures. In hydrogen atmosphere a segregation of small (∼1nm) Ru crystallites occurred at the surface of the Ce0.89Ru0.11O2 mixed oxide. Only small increase of the mean crystallite size of Ru (to 2nm) occurred after reduction at 1000°C. The unique resistance of Ru to sintering is assigned to a special epitaxial orientation Ru (002)∥CeO2 (111), which persisted up to the highest temperature of reduction, due to very strong surface bonding. Contrary to a situation in oxidizing atmosphere, doping with Ru had no significant effect on the sintering of ceria in hydrogen. Partial substitution of Ru for Ce strongly enhances the reducibility of ceria at low temperatures and its activity in catalytic combustion of CO and soot.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
