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Kettner M, Duchoň T, Wolf MJ, Kullgren J, Senanayake SD, Hermansson K, Veltruská K, Nehasil V. Anion-mediated electronic effects in reducible oxides: Tuning the valence band of ceria via fluorine doping. J Chem Phys 2019; 151:044701. [PMID: 31370552 DOI: 10.1063/1.5109955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Combining experimental spectroscopy and hybrid density functional theory calculations, we show that the incorporation of fluoride ions into a prototypical reducible oxide surface, namely, ceria(111), can induce a variety of nontrivial changes to the local electronic structure, beyond the expected increase in the number of Ce3+ ions. Our resonant photoemission spectroscopy results reveal new states above, within, and below the valence band, which are unique to the presence of fluoride ions at the surface. With the help of hybrid density functional calculations, we show that the different states arise from fluoride ions in different atomic layers in the near surface region. In particular, we identify a structure in which a fluoride ion substitutes for an oxygen ion at the surface, with a second fluoride ion on top of a surface Ce4+ ion giving rise to F 2p states which overlap the top of the O 2p band. The nature of this adsorbate F--Ce4+ resonant enhancement feature suggests that this bond is at least partially covalent. Our results demonstrate the versatility of anion doping as a potential means of tuning the valence band electronic structure of ceria.
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Affiliation(s)
- Miroslav Kettner
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Tomáš Duchoň
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Matthew J Wolf
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Jolla Kullgren
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Sanjaya D Senanayake
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Kersti Hermansson
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Kateřina Veltruská
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Václav Nehasil
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
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You R, Zhang X, Luo L, Pan Y, Pan H, Yang J, Wu L, Zheng X, Jin Y, Huang W. NbO x /CeO 2 -rods catalysts for oxidative dehydrogenation of propane: Nb–CeO 2 interaction and reaction mechanism. J Catal 2017. [DOI: 10.1016/j.jcat.2016.12.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ostroverkh A, Johánek V, Kúš P, Šedivá R, Matolín V. Efficient Ceria-Platinum Inverse Catalyst for Partial Oxidation of Methanol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:6297-6309. [PMID: 27254727 DOI: 10.1021/acs.langmuir.6b01316] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ceria-platinum-based bilayered thin films deposited by magnetron sputtering were developed and tested in regard to their catalytic activity for methanol oxidation by employing a temperature-programmed reaction (TPR) technique. The composition and structure of the samples were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Both conventional (oxide-supported metal nanoparticles [NPs]) and inverse configurations (metal with oxide overlayer) were analyzed to uncover the structural dependence of activity and selectivity of these catalysts with respect to different pathways of methanol oxidation. We clearly demonstrate that the amount of cerium oxide (ceria) loading has a profound influence on methanol oxidation reaction characteristics. Adding a noncontinuous adlayer of ceria greatly enhances the catalytic performance of platinum (Pt) in favor of partial oxidation of methanol (POM), gaining an order of magnitude in the absolute yield of hydrogen. Moreover, the undesired by-production of carbon monoxide (CO) is strongly suppressed, making the ceria-platinum inverse catalyst a great candidate for clean hydrogen production. It is suggested that the methanol oxidation process is facilitated by the synergistic effect between both components of the inverse catalyst (involving oxygen from ceria and providing a reaction site on the adjacent Pt surface) as well as by the fact that the ability of ceria to exchange oxygen (i.e., to alter the oxidation state of Ce between 3+ and 4+) during the reaction is inversely proportional to its thickness. The increased redox capability of the discontinuous ceria adlayer shifts the preferred reaction pathway from dehydrogenation of hydroxymethyl intermediate to CO in favor of its oxidation to formate.
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Affiliation(s)
- Anna Ostroverkh
- Department of Surface and Plasma Science, Charles University in Prague , V Holesovickach 2, 180 00 Prague 8, Czech Republic
| | - Viktor Johánek
- Department of Surface and Plasma Science, Charles University in Prague , V Holesovickach 2, 180 00 Prague 8, Czech Republic
| | - Peter Kúš
- Department of Surface and Plasma Science, Charles University in Prague , V Holesovickach 2, 180 00 Prague 8, Czech Republic
| | - Romana Šedivá
- Department of Surface and Plasma Science, Charles University in Prague , V Holesovickach 2, 180 00 Prague 8, Czech Republic
| | - Vladimír Matolín
- Department of Surface and Plasma Science, Charles University in Prague , V Holesovickach 2, 180 00 Prague 8, Czech Republic
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Lykhach Y, Kozlov SM, Skála T, Tovt A, Stetsovych V, Tsud N, Dvořák F, Johánek V, Neitzel A, Mysliveček J, Fabris S, Matolín V, Neyman KM, Libuda J. Counting electrons on supported nanoparticles. NATURE MATERIALS 2016; 15:284-8. [PMID: 26657332 DOI: 10.1038/nmat4500] [Citation(s) in RCA: 268] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 11/03/2015] [Indexed: 05/03/2023]
Abstract
Electronic interactions between metal nanoparticles and oxide supports control the functionality of nanomaterials, for example, the stability, the activity and the selectivity of catalysts. Such interactions involve electron transfer across the metal/support interface. In this work we quantify this charge transfer on a well-defined platinum/ceria catalyst at particle sizes relevant for heterogeneous catalysis. Combining synchrotron-radiation photoelectron spectroscopy, scanning tunnelling microscopy and density functional calculations we show that the charge transfer per Pt atom is largest for Pt particles of around 50 atoms. Here, approximately one electron is transferred per ten Pt atoms from the nanoparticle to the support. For larger particles, the charge transfer reaches its intrinsic limit set by the support. For smaller particles, charge transfer is partially suppressed by nucleation at defects. These mechanistic and quantitative insights into charge transfer will help to make better use of particle size effects and electronic metal-support interactions in metal/oxide nanomaterials.
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Affiliation(s)
- Yaroslava Lykhach
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany
| | - Sergey M Kozlov
- Departament de Química Física and Institut de Quimica Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona, Spain
| | - Tomáš Skála
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Andrii Tovt
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Vitalii Stetsovych
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Nataliya Tsud
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Filip Dvořák
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Viktor Johánek
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Armin Neitzel
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany
| | - Josef Mysliveček
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Stefano Fabris
- CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche and SISSA, Via Bonomea 265, I-34136 Trieste, Italy
| | - Vladimír Matolín
- Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Konstantin M Neyman
- Departament de Química Física and Institut de Quimica Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, 08028 Barcelona, Spain
- Institucio Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - Jörg Libuda
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany
- Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany
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Mysliveček J, Matolín V, Matolínová I. Heteroepitaxy of Cerium Oxide Thin Films on Cu(111). MATERIALS 2015; 8:6346-6359. [PMID: 28793567 PMCID: PMC5512914 DOI: 10.3390/ma8095307] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/12/2015] [Accepted: 09/14/2015] [Indexed: 01/09/2023]
Abstract
An important part of fundamental research in catalysis is based on theoretical and modeling foundations which are closely connected with studies of single-crystalline catalyst surfaces. These so-called model catalysts are often prepared in the form of epitaxial thin films, and characterized using advanced material characterization techniques. This concept provides the fundamental understanding and the knowledge base needed to tailor the design of new heterogeneous catalysts with improved catalytic properties. The present contribution is devoted to development of a model catalyst system of CeO2 (ceria) on the Cu(111) substrate. We propose ways to experimentally characterize and control important parameters of the model catalyst—the coverage of the ceria layer, the influence of the Cu substrate, and the density of surface defects on ceria, particularly the density of step edges and the density and the ordering of the oxygen vacancies. The large spectrum of controlled parameters makes ceria on Cu(111) an interesting alternative to a more common model system ceria on Ru(0001) that has served numerous catalysis studies, mainly as a support for metal clusters.
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Affiliation(s)
- Josef Mysliveček
- Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 18000 Prague 8, Czech Republic.
| | - Vladimir Matolín
- Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 18000 Prague 8, Czech Republic.
| | - Iva Matolínová
- Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 18000 Prague 8, Czech Republic.
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Photoemission Study of Methanol Adsorption and Decomposition on Pd/CeO2(111)/Cu(111) Thin Film Model Catalyst. Catal Letters 2015. [DOI: 10.1007/s10562-015-1557-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Stetsovych V, Pagliuca F, Dvořák F, Duchoň T, Vorokhta M, Aulická M, Lachnitt J, Schernich S, Matolínová I, Veltruská K, Skála T, Mazur D, Mysliveček J, Libuda J, Matolín V. Epitaxial Cubic Ce2O3 Films via Ce-CeO2 Interfacial Reaction. J Phys Chem Lett 2013; 4:866-871. [PMID: 26291348 DOI: 10.1021/jz400187j] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Thin films of reduced ceria supported on metals are often applied as substrates in model studies of the chemical reactivity of ceria based catalysts. Of special interest are the properties of oxygen vacancies in ceria. However, thin films of ceria prepared by established methods become increasingly disordered as the concentration of vacancies increases. Here, we propose an alternative method for preparing ordered reduced ceria films based on the physical vapor deposition and interfacial reaction of Ce with CeO2 films. The method yields bulk-truncated layers of cubic c-Ce2O3. Compared to CeO2 these layers contain 25% of perfectly ordered vacancies in the surface and subsurface allowing well-defined measurements of the properties of ceria in the limit of extreme reduction. Experimentally, c-Ce2O3(111) layers are easily identified by a characteristic 4 × 4 surface reconstruction with respect to CeO2(111). In addition, c-Ce2O3 layers represent an experimental realization of a normally unstable polymorph of Ce2O3. During interfacial reaction, c-Ce2O3 nucleates on the interface between CeO2 buffer and Ce overlayer and is further stabilized most likely by the tetragonal distortion of the ceria layers on Cu. The characteristic kinetics of the metal-oxide interfacial reactions may represent a vehicle for making other metastable oxide structures experimentally available.
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Affiliation(s)
- Vitalii Stetsovych
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Federico Pagliuca
- ‡Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia and S3, Istituto Nanoscienze - CNR, Via G. Campi 213/a, 41125 Modena, Italy
| | - Filip Dvořák
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Tomáš Duchoň
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Mykhailo Vorokhta
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Marie Aulická
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Jan Lachnitt
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Stefan Schernich
- §Lehrstuhl für Physikalische Chemie II and Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Iva Matolínová
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Kateřina Veltruská
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Tomáš Skála
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Daniel Mazur
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Josef Mysliveček
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
| | - Jörg Libuda
- §Lehrstuhl für Physikalische Chemie II and Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Vladimír Matolín
- †Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, Czech Republic
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Schernich S, Laurin M, Lykhach Y, Steinrück HP, Tsud N, Skála T, Prince KC, Taccardi N, Matolín V, Wasserscheid P, Libuda J. Functionalization of Oxide Surfaces through Reaction with 1,3-Dialkylimidazolium Ionic Liquids. J Phys Chem Lett 2013; 4:30-35. [PMID: 26291207 DOI: 10.1021/jz301856a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Practical applications of ionic liquids (ILs) often involve IL/oxide interfaces, but little is known regarding their interfacial chemistry. The unusual physicochemical properties of ILs, including their exceptionally low vapor pressure, provide access to such interfaces using a surface science approach in ultrahigh vacuum (UHV). We have applied synchrotron radiation photoelectron spectroscopy (SR-PES) to the study of a thin film of the ionic liquid [C6C1Im][Tf2N] prepared in situ in UHV on ordered stoichiometric CeO2(111) and partially reduced CeO2-x. On the partially reduced surface, we mostly observe decomposition of the anion. On the stoichiometric CeO2(111) surface, however, a layer of surface-anchored organic products with high thermal stability is formed upon reaction of the cation. The suggested acid-base reaction pathway may provide well-defined functionalized IL/solid interfaces on basic oxides.
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Affiliation(s)
| | | | | | | | - Nataliya Tsud
- ‡Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Tomáš Skála
- ‡Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Kevin C Prince
- §Sincrotrone Trieste SCpA, Strada Statale 14, km163.5,34149 Basovizza-Trieste, Italy
| | | | - Vladimír Matolín
- ‡Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
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Kong DD, Pan YH, Wang GD, Pan HB, Zhu JF. Growth and Electronic Properties of Ag Nanoparticles on Reduced CeO2−x(111) Films. CHINESE J CHEM PHYS 2012. [DOI: 10.1088/1674-0068/25/06/713-718] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Matolín V, Matolínová I, Dvořák F, Johánek V, Mysliveček J, Prince K, Skála T, Stetsovych O, Tsud N, Václavů M, Šmíd B. Water interaction with CeO2(111)/Cu(111) model catalyst surface. Catal Today 2012. [DOI: 10.1016/j.cattod.2011.05.032] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Vayssilov GN, Lykhach Y, Migani A, Staudt T, Petrova GP, Tsud N, Skála T, Bruix A, Illas F, Prince KC, Matolín V, Neyman KM, Libuda J. Support nanostructure boosts oxygen transfer to catalytically active platinum nanoparticles. NATURE MATERIALS 2011; 10:310-315. [PMID: 21423188 DOI: 10.1038/nmat2976] [Citation(s) in RCA: 456] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 01/27/2011] [Indexed: 05/30/2023]
Abstract
Interactions of metal particles with oxide supports can radically enhance the performance of supported catalysts. At the microscopic level, the details of such metal-oxide interactions usually remain obscure. This study identifies two types of oxidative metal-oxide interaction on well-defined models of technologically important Pt-ceria catalysts: (1) electron transfer from the Pt nanoparticle to the support, and (2) oxygen transfer from ceria to Pt. The electron transfer is favourable on ceria supports, irrespective of their morphology. Remarkably, the oxygen transfer is shown to require the presence of nanostructured ceria in close contact with Pt and, thus, is inherently a nanoscale effect. Our findings enable us to detail the formation mechanism of the catalytically indispensable Pt-O species on ceria and to elucidate the extraordinary structure-activity dependence of ceria-based catalysts in general.
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Zhao YX, Wu XN, Ma JB, He SG, Ding XL. Characterization and reactivity of oxygen-centred radicals over transition metal oxide clusters. Phys Chem Chem Phys 2011; 13:1925-38. [DOI: 10.1039/c0cp01171a] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Electronic Conductivity of CeO[sub 2]: Its Dependence on Oxygen Partial Pressure and Temperature. ACTA ACUST UNITED AC 2010. [DOI: 10.1149/1.3276731] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Wu XN, Zhao YX, Xue W, Wang ZC, He SG, Ding XL. Active sites of stoichiometric cerium oxide cations (CemO2m+) probed by reactions with carbon monoxide and small hydrocarbon molecules. Phys Chem Chem Phys 2010; 12:3984-97. [DOI: 10.1039/b925294k] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Matolín V, Matolínová I, Sedlácek L, Prince KC, Skála T. A resonant photoemission applied to cerium oxide based nanocrystals. NANOTECHNOLOGY 2009; 20:215706. [PMID: 19423945 DOI: 10.1088/0957-4484/20/21/215706] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cerium 4f level occupation determines the properties of cerium oxide based catalysts in a significant way. The Ce 4f level of nanosized cerium oxide particles was investigated with the use of resonant photoelectron spectroscopy in the Ce 4d-4f photoabsorption region. A strong interaction of ceria with different additives, e.g. Pd and Sn, led to a partial Ce4+-->Ce3+ transition that was observed as a significant resonance enhancement of 4f photoemission intensity. Increases of the CO oxidation catalytic activity were observed simultaneously. The ratio of resonance enhancement of Ce photoemission intensity DCe(3+)/DCe(4+) was used to monitor Ce(3+) and Ce(4+) state occupation. The relative parameter DCe(3+)/DCe(4+) was found to be particularly useful in the case of photoemission studies of nanopowder ceria catalysts.
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Affiliation(s)
- V Matolín
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University in Prague, Prague 8, Czech Republic.
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Skála T, Sutara F, Skoda M, Prince KC, Matolín V. Palladium interaction with CeO(2), Sn-Ce-O and Ga-Ce-O layers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:055005. [PMID: 21817292 DOI: 10.1088/0953-8984/21/5/055005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Using photoemission, we have studied the interaction of palladium with thin layers of stoichiometric ceria (Ce(4+) character) and two mixed oxides, Ga-Ce-O and Sn-Ce-O, where cerium in the Ce(3+) oxidation state is present. Palladium was found to partially reduce the CeO(2) layer by introducing oxygen vacancies most probably in the vicinity of the growing Pd particles. In mixed oxide systems palladium very strongly interacts with both added metals-gallium and tin-leading to a breaking of metal-ceria bonds and the establishment of Pd-Ga(Sn) intermetallic compounds. As a consequence the ceria reoxidizes back to a Ce(4+) oxidation state.
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Affiliation(s)
- T Skála
- Sincrotrone Trieste, Strada Statale 14, km 163.5, I-34012 Basovizza-Trieste, Italy
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Škoda M, Cabala M, Matolínová I, Prince KC, Skála T, Šutara F, Veltruská K, Matolín V. Interaction of Au with CeO2(111): A photoemission study. J Chem Phys 2009; 130:034703. [DOI: 10.1063/1.3046684] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Matolín V, Cabala M, Cháb V, Matolínová I, Prince KC, Škoda M, Šutara F, Skála T, Veltruská K. A resonant photoelectron spectroscopy study of Sn(Ox) doped CeO2 catalysts. SURF INTERFACE ANAL 2008. [DOI: 10.1002/sia.2625] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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