XPS and UPS studies of oxygen adsorption over clean and carbon-modified silver surfaces

Boronin, A. I.; Bukhityarov, V.I.; Vishnevskii, A. L.; Боресков, Г. К.; Savchenko, V. I.

doi:10.1016/0039-6028(88)90606-1

Cited by 78 publications

(50 citation statements)

References 28 publications

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“…Although gas phase molecules do not contribute to XPS spectra under UHV conditions, at elevated pressure of in-situ experiments their concentration in the volume over the sample surface irradiated by the incident X-ray beam can become comparable with the concentration of surface species. And indeed, as shown by us earlier, measurable gas phase XPS signals appeared in similar experiments when pressure exceeds 0.05 mbar [6,[27][28]. Gas phase molecules, however, exhibit generally narrower XPS lines than surface species.…”

Section: Resultssupporting

confidence: 75%

“…Additional criterion, which reinforced the assignment, was the temperature range in which they occurred. For example, assignment of an O1s feature at ~ 530.5 eV and a C1s feature at ~ 287.5 eV observed at T = 370 K to surface carbonates, CO 3,ads [6,[32][33][34][35], was based not only on the BE values, but also on their stability on silver surfaces at ambient temperatures only. At 420 K, carbonates decompose to adsorbed oxygen and CO 2 , which desorbs from the surface [6,[31][32][33][34].…”

Section: Resultsmentioning

confidence: 99%

“…The sample was cleaned by the standard cleaning procedure: Ar + sputtering, annealing in 10 mbar of O 2 at 570 K, and flashing up to 800 K in vacuum [1][2][3][4][5][6][7]. Due to the residual gas pressure of 10 -8 mbar in our chamber, the sample at room temperature was always covered by some hydrocarbon contaminants.…”

Section: Methodsmentioning

confidence: 99%

“…Silver catalysts for ethylene epoxidation have in the past also mostly been studied under ex situ conditions with high-vacuum based surface science techniques [1][2][3][4][5][6][7][8]. Our own previous studies were also not free from this drawback [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

Bukhtiyarov

Nizovskiĭ

Bluhm

et al. 2006

Journal of Catalysis

136

129

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Ethylene epoxidation over silver was investigated by combined in-situ X-ray photoelectron spectroscopy (XPS) and proton-transfer reaction mass-spectrometry (PTRMS) at temperatures from 300 to 520 K and in the pressure range from 0.07 to 1 mbar. Ethylene oxide was present among the reaction products at T ≥ 420 K and P ≥ 0.3 mbar. The catalytically active surface contains two oxygen species -nucleophilic and electrophilic oxygen. The observed correlation between the abundance of electrophilic oxygen and the yield of ethylene oxide expressed as C 2 H 4 O partial pressure indicates that namely this oxygen species oxidizes ethylene to ethylene oxide. Opposite trend is observed for nucleophilic oxygen: the higher is the abundance of this species, the lower is the yield of ethylene oxide. This result is in line with the known fact that nucleophilic oxygen due to its oxidic nature is active in total oxidation of ethylene to CO 2 and H 2 O. The low activity of silver at T < 420 K is caused by the presence of carbonates and carbonaceous residues at the silver surface that reduce the available silver surface area for the catalytic reaction. Reduction of the surface area available for the formation of active species due to accumulation of the embedded oxygen species explains also the decrease of the rate of ethylene oxide formation with time observed for T ≥ 470 K.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

Bukhtiyarov

Nizovskiĭ

Bluhm

et al. 2006

Journal of Catalysis

136

129

View full text Add to dashboard Cite

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“…This basic concept has been used in a number of HP-XPS instruments that were developed over the past 30 years and that operate at pressures of up to 1 Torr. [12][13][14][15][16][17][18][19] Several of these HP-XPS instruments have been used to study reactions on model catalyst surfaces, such as the interaction of oxygen with silver surfaces, 20,21 methanol oxidation on Cu, 22 CO adsorption on Pd(111), 23 reaction of copper and copper oxide with SO 2 , 24 the reduction of nickel oxide in H 2 , 25 and the adsorption of CO on Pd(111).…”

Section: Introductionmentioning

confidence: 99%

In SituX-Ray Photoelectron Spectroscopy Studies of Gas-Solid Interfaces at Near-Ambient Conditions

et al. 2007

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X-ray photoelectron spectroscopy (XPS) is a quantitative, chemically specific technique with a probing depth of a few angstroms to a few nanometers.It is therefore ideally suited to investigate the chemical nature of the surfaces of catalysts. Because of the scattering of electrons by gas molecules, XPS is generally performed under vacuum conditions. However, for thermodynamic and/or kinetic reasons, the catalyst's chemical state observed under vacuum reaction conditions is not necessarily the same as that of a catalyst under realistic operating pressures. Therefore, investigations of catalysts should ideally be performed under reaction conditions, i.e., in the presence of a gas or gas mixtures.Using differentially pumped chambers separated by small apertures, XPS can operate at pressures of up to 1 Torr, and with a recently developed differentially pumped lens system, the pressure limit has been raised to about 10 Torr. Here, we describe the technical aspects of high-pressure XPS and discuss recent applications of this technique to oxidation and heterogeneous catalytic reactions on metal surfaces.

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Surface Chemical Composition

Taglauer

2008

Handbook of Heterogeneous Catalysis

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The sections in this article are Introduction Electron Spectroscopies ( AES , XPS ) Basic Aspects Auger Electron Spectroscopy ( AES ) X ‐Ray Photoemission Spectroscopy ( XPS ) Ion Scattering Spectroscopies General Aspects Collision Kinematics Low‐Energy Ions R utherford Scattering Secondary Particles Secondary Ion Mass Spectrometry Secondary Neutrals Photon Stimulation

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XPS and UPS studies of oxygen adsorption over clean and carbon-modified silver surfaces

Cited by 78 publications

References 28 publications

Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

In SituX-Ray Photoelectron Spectroscopy Studies of Gas-Solid Interfaces at Near-Ambient Conditions

Surface Chemical Composition

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