Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates

Handle URI:
http://hdl.handle.net/10754/563206
Title:
Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates
Authors:
Naganuma, Tamaki; Traversa, Enrico ( 0000-0001-6336-941X )
Abstract:
Abundant oxygen vacancies coexisting with Ce3+ ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce3+ ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce3+ ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce3+ and Ce4+ ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce3+ ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce 3+ ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce3+ ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce 3+ to Ce4+ occurred at 350 °C in air. Highly concentrated Ce3+ ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce 3+ stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce3+ sites. This study also illuminates the potential interaction mechanisms of stable Ce3+ ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. © The Royal Society of Chemistry 2014.
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program; KAUST Solar Center (KSC); Materials for Energy Conversion and Storage (MECS) Lab
Publisher:
Royal Society of Chemistry (RSC)
Journal:
Nanoscale
Issue Date:
2014
DOI:
10.1039/c3nr06662b
Type:
Article
ISSN:
20403364
Sponsors:
This work was funded by The Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan under the frame of the WPI Program.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program; KAUST Solar Center (KSC)

Full metadata record

DC FieldValue Language
dc.contributor.authorNaganuma, Tamakien
dc.contributor.authorTraversa, Enricoen
dc.date.accessioned2015-08-03T11:38:08Zen
dc.date.available2015-08-03T11:38:08Zen
dc.date.issued2014en
dc.identifier.issn20403364en
dc.identifier.doi10.1039/c3nr06662ben
dc.identifier.urihttp://hdl.handle.net/10754/563206en
dc.description.abstractAbundant oxygen vacancies coexisting with Ce3+ ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce3+ ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce3+ ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce3+ and Ce4+ ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce3+ ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce 3+ ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce3+ ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce 3+ to Ce4+ occurred at 350 °C in air. Highly concentrated Ce3+ ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce 3+ stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce3+ sites. This study also illuminates the potential interaction mechanisms of stable Ce3+ ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. © The Royal Society of Chemistry 2014.en
dc.description.sponsorshipThis work was funded by The Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan under the frame of the WPI Program.en
dc.publisherRoyal Society of Chemistry (RSC)en
dc.titleAir, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substratesen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMaterials Science and Engineering Programen
dc.contributor.departmentKAUST Solar Center (KSC)en
dc.contributor.departmentMaterials for Energy Conversion and Storage (MECS) Laben
dc.identifier.journalNanoscaleen
dc.contributor.institutionInternational Center for Materials Nanoarchitectonics (MANA), Biomaterials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japanen
kaust.authorTraversa, Enricoen
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