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An, Kwangjin
Advanced Nanocatalysis Lab (An Lab)
Research Interests
  • Nanoparticle catalytsts, catalytic activity, selectivity, and stability, strong metal-support interactions, CO2 utilization, biomass conversion, Plastic Up-cycling

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Pt-mediated Reversible Reduction and Expansion of CeO2 in Pt Nanoparticle/mesoporous CeO2 Catalyst: In situ X-ray Spectroscopy and Diffraction Studies under Redox (H2 and O2) Atmospheres

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Title
Pt-mediated Reversible Reduction and Expansion of CeO2 in Pt Nanoparticle/mesoporous CeO2 Catalyst: In situ X-ray Spectroscopy and Diffraction Studies under Redox (H2 and O2) Atmospheres
Author
Alayoglu, SelimAn, KwangjinMelaet, GeromeChen, ShiyouBernardi, FabianoWang, Lin WangLindeman, Avery E.Musselwhite, NathanGuo, JinghuaLiu, ZhiMarcus, Matthew A.Somorjai, Gabor A.
Keywords
Activation barriers; Fluorescence spectra; Hydrogen spill overs; Identical conditions; Near surface regions; Reversible expansion; Reversible reduction; Total electron yield
Issue Date
2013-12
Publisher
AMER CHEMICAL SOC
Citation
JOURNAL OF PHYSICAL CHEMISTRY C, v.117, no.50, pp.26608 - 26616
Abstract
Here, we report the Pt nanoparticle mediated reduction (oxidation) and lattice expansion (contraction) of mesoporous CeO2 under H 2 (O2) atmospheres and in the temperature range of 50-350 C. We found that CeO2 in the Pt/CeO2 catalyst was partially reduced in H2 (and fully oxidized back in O2) as demonstrated by several in situ techniques: APXPS spectra (4d core levels) for the topmost surface, NEXAFS total electron yield spectra (at the M5,4 edges) in the near surface regions, and (N)EXAFS fluorescence spectra (at the L3 edge) in the bulk. Moreover, XRD and EXAFS showed the reversible expansion and contraction of the CeO2 unit cell in H2 and O2 environments, respectively. The expansion of the CeO2 cell was mainly associated with the formation of oxygen vacancies as a result of the Pt-mediated reduction of Ce4+ to Ce3+. We also found that pure mesoporous CeO2 can not be reduced in H2 under identical conditions but can be partially reduced at above 450 C as revealed by APXPS. The role of Pt in H2 was identified as a catalytic one that reduces the activation barrier for the reduction of CeO2 via hydrogen spillover. © 2013 American Chemical Society.
URI
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DOI
10.1021/jp407280e
ISSN
1932-7447
Appears in Collections:
ECHE_Journal Papers
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JPCC 2013,117,26608, Pt-Mediated Reversible Reduction and Expansion of CeO2 in Pt NP m-CeO2 Catalyst.pdf Download

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