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Redox properties of...
Redox properties of titanium oxides on Pt3Ti
- Artikel/kapitelEngelska1995
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2002-05-01
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American Chemical Society (ACS),1995
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LIBRIS-ID:oai:DiVA.org:ltu-6929
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https://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-6929URI
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https://doi.org/10.1021/j100034a030DOI
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https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-83031URI
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Språk:engelska
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Sammanfattning på:engelska
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Ämneskategori:ref swepub-contenttype
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Ämneskategori:art swepub-publicationtype
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Upprättat; 1995; 20080612 (ysko)
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Correspondence Address: Paul, J.; KTH/Royal Institute of Technology, Physics III, 100 44 Stockholm, Sweden NR 20140805
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The morphology and electronic structure of surface-segregated titanium oxides on Pt3Ti(111) are presented. Core level photoemission spectra at grazing emission reveal two states of oxidation: a dominant and reducible four-valent oxide together with a small amount of a three-valent oxide is produced by oxidation in 0 2 at and below 400°C; an irreducible three-valent oxide by oxidation in 02 at and above 450 °C. The ratio between the active four-valent and the inactive three-valent oxides decreases with increasing oxidation temperature. The probability for reduction by CO is almost unity for the Ti 4+ oxide, and the conclusion must be that the four-valent oxide plays an active role for catalytic reactions. Scanning tunneling measurements relate these observations to changes in the dispersion and nucleation of the oxide overlayer. The four-valent oxide grows as islands with remaining areas open for CO adsorption while the three-valent oxide spreads on and blocks the crystal surface. Photoemission spectra relate these dispersion effects to an electronic interaction between the Ti 3+ oxide and adjacent Pt atoms. The above observations are in accordance with the common picture of dispersion effects in titania-supported SMSI catalysts and prove that interfacial energies play a crucial role whether the dominant phase is metallic or an oxide.
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Cameron, S.
(författare)
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Göthelid, M.
(författare)
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Hammar, M.KTH,Fysik
(författare)
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Paul, Jan
(författare)
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KTHFysik
(creator_code:org_t)
Sammanhörande titlar
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Ingår i:Journal of Physical Chemistry: American Chemical Society (ACS)99:34, s. 12892-128950022-36541541-5740
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