Epitaxial growth of continuous CeO2(111) ultra-thin films on Cu(111)

Šutara, F.; Cabala, M.; Sedláček, L.; Škála, Tomáš; Škoda, M.; Matolín, Vladimı́r; Prince, Kevin C.; Cháb, V.

doi:10.1016/j.tsf.2007.11.013

Cited by 90 publications

(103 citation statements)

References 17 publications

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“…5 For further details concerning the preparation procedure we refer to the literature. 54,56,57,60 Mg metal (Goodfellow, 99.9%) was deposited from a resistively heated Mo crucible onto the fully stoichiometric CeO 2 film at 300 K. The amount of the deposited material was estimated by the attenuation of the intensity of the Cu 2p 3/2 photoemission signal, acquired using an Al-Ka X-ray source at g = 201. The estimated thickness of Mg was about 0.6 nm.…”

Section: Methodology Experimentalmentioning

confidence: 99%

On the interaction of Mg with the (111) and (110) surfaces of ceria

Nolan

Lykhach

Tsud

et al. 2012

Phys. Chem. Chem. Phys.

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Access to the full text of the published version may require a subscription. Please note that, in the typefaces we use, an italic vee looks like this: n, and a Greek nu looks like this: n. RightsWe will publish articles on the web as soon as possible after receiving your corrections; no late corrections will be made.Please return your final corrections, where possible within 48 hours of receipt, by e-mail to: pccp@rsc.org.Reprints-Electronic (PDF) reprints will be provided free of charge to the corresponding author. The catalytic activity of cerium dioxide can be modified by deposition of alkaline earth oxide layers or nanoparticles or by substitutional doping of metal cations at the Ce site in ceria. In order to understand the effect of Mg oxide deposition and doping, a combination of experiment and first principles simulations is a powerful tool. In this paper, we examine the interaction of Mg with the ceria (111) surface using both angle resolved X-ray (ARXPS) and resonant (RPES) photoelectron spectroscopy measurements and density functional theory (DFT) corrected for onsite Coulomb interactions (DFT + U). With DFT + U, we also examine the interaction of Mg with the ceria (110) (111) surface. The combined results provide a basis for deeper insights into the catalytic behaviour of ceria-based mixed oxide catalysts.

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Section: Methodology Experimentalmentioning

confidence: 99%

On the interaction of Mg with the (111) and (110) surfaces of ceria

Nolan

Lykhach

Tsud

et al. 2012

Phys. Chem. Chem. Phys.

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“…Alternatively, a formation of a ceria film that is epitaxially grown on metal substrates has been studied extensively. The substrates used in such researches include Pd(111), 4 Pt(111), [5][6][7] Rh(111), 8 Ni(111), 9 Cu(111), 10,11 and Ru(0001). 9,[12][13][14][15] It has been pointed out that step-edges, kinks, and vacancies are active sites for the catalytic reaction.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial growth of CeO2(111) film on Ru(0001): Scanning tunneling microscopy (STM) and x-ray photoemission spectroscopy (XPS) study

Hasegawa¹,

Shahed²,

Sainoo³

et al. 2014

The Journal of Chemical Physics

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We formed an epitaxial film of CeO2(111) by sublimating Ce atoms on Ru(0001) surface kept at elevated temperature in an oxygen ambient. X-ray photoemission spectroscopy measurement revealed a decrease of Ce4+/Ce3+ ratio in a small temperature window of the growth temperature between 1070 and 1096 K, which corresponds to the reduction of the CeO2(111). Scanning tunneling microscope image showed that a film with a wide terrace and a sharp step edge was obtained when the film was grown at the temperatures close to the reduction temperature, and the terrace width observed on the sample grown at 1060 K was more than twice of that grown at 1040 K. On the surface grown above the reduction temperature, the surface with a wide terrace and a sharp step was confirmed, but small dots were also seen in the terrace part, which are considerably Ce atoms adsorbed at the oxygen vacancies on the reduced surface. This experiment demonstrated that it is required to use the substrate temperature close to the reduction temperature to obtain CeO2(111) with wide terrace width and sharp step edges.

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“…The samples were prepared by the deposition of a Pt layer with a nominal thickness of 0.5 nm onto a wellordered 2.5 nm thick CeO 2 A C H T U N G T R E N N U N G (111)/CuA C H T U N G T R E N N U N G (111) film at 300 K. Details of the sample preparation and treatment procedure can be found in the literature. [53][54][55] The Pt/CeO 2 /CuA C H T U N G T R E N N U N G (111) samples were exposed to a collimated supersonic molecular beam (SSMB) of CH 4 at a sample temperature of 100 K. The SSMB was generated from a resistively heated 100 mm molybdenum nozzle at a seeding ratio of 1:10 in a He environment. Previously, the kinetic energy (KE) of CH 4 was determined to be 68 kJ mol…”

mentioning

confidence: 99%

“…The chemical and structural properties of the film were investigated previously. [54,55,74] We have also investigated the growth of Pt nanoparticles on the film by means of scanning tunneling microscopy (STM). [53] It was found that Pt grows in the form of three-dimensional islands with a nucleation density of around 5 10 12 cm À2 under the conditions applied.…”

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confidence: 99%

Methane Activation by Platinum: Critical Role of Edge and Corner Sites of Metal Nanoparticles

Viñes

Lykhach

Staudt

et al. 2010

Chemistry A European J

133

107

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Complete dehydrogenation of methane is studied on model Pt catalysts by means of state-of-the-art DFT methods and by a combination of supersonic molecular beams with high-resolution photoelectron spectroscopy. The DFT results predict that intermediate species like CH(3) and CH(2) are specially stabilized at sites located at particles edges and corners by an amount of 50-80 kJ mol(-1). This stabilization is caused by an enhanced activity of low-coordinated sites accompanied by their special flexibility to accommodate adsorbates. The kinetics of the complete dehydrogenation of methane is substantially modified according to the reaction energy profiles when switching from Pt(111) extended surfaces to Pt nanoparticles. The CH(3) and CH(2) formation steps are endothermic on Pt(111) but markedly exothermic on Pt(79). An important decrease of the reaction barriers is observed in the latter case with values of approximately 60 kJ mol(-1) for first C-H bond scission and 40 kJ mol(-1) for methyl decomposition. DFT predictions are experimentally confirmed by methane decomposition on Pt nanoparticles supported on an ordered CeO(2) film on Cu(111). It is shown that CH(3) generated on the Pt nanoparticles undergoes spontaneous dehydrogenation at 100 K. This is in sharp contrast to previous results on Pt single-crystal surfaces in which CH(3) was stable up to much higher temperatures. This result underlines the critical role of particle edge sites in methane activation and dehydrogenation.

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Epitaxial growth of continuous CeO2(111) ultra-thin films on Cu(111)

Cited by 90 publications

References 17 publications

On the interaction of Mg with the (111) and (110) surfaces of ceria

On the interaction of Mg with the (111) and (110) surfaces of ceria

Epitaxial growth of CeO2(111) film on Ru(0001): Scanning tunneling microscopy (STM) and x-ray photoemission spectroscopy (XPS) study

Methane Activation by Platinum: Critical Role of Edge and Corner Sites of Metal Nanoparticles

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