Chemisorption of oxygen on the silver (111) surface

Rovida, G.; Pratesi, F; Maglietta, M.; Ferroni, E.

doi:10.1016/0039-6028(74)90229-5

Cited by 179 publications

(80 citation statements)

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“…Of direct relevance to the present study was the 1974 observation by Rovida et al [1] that a (4 Â 4) LEED superstructure forms upon exposure of O to Ag{1 1 1}. The (4 Â 4) superstructure, which is stable in temperature programmed desorption (TPD) experiments to ca.…”

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confidence: 59%

“…The microscopic structure of this reconstruction is still, however, not clear. Originally the (4 Â 4) pattern was interpreted in terms of the growth of a {1 1 1} orientated trilayer of Ag 2 O epitaxed to the Ag{1 1 1} surface [1]. Based on a coverage deter- www.elsevier.com/locate/cplett mination of 0:41 AE 10% of a monolayer (ML), Campbell proposed that this trilayer consisted of a plane of Ag between two planes of oxygens [2].…”

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confidence: 99%

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Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{1 1 1}

Michaelides

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Sautet

et al. 2003

Chemical Physics Letters

118

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With density functional theory, we have examined oxygen adsorption at surface and subsurface sites of Ag{1 1 1}. The microscopic structure of Ag oxide epitaxed to Ag{1 1 1} has also been determined. In agreement with a recent scanning tunneling microscopy study, non-stoichiometric oxide growth is favoured over the previously assumed stoichiometric growth. An ab initio phase diagram for O on Ag{1 1 1} has been constructed from the adsorption free energy of the various O and Ag oxide phases. The key finding is that under real conditions for ethylene epoxidation the active catalyst is likely to be non-stoichiometric Ag oxide.

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confidence: 59%

mentioning

confidence: 99%

Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{1 1 1}

Michaelides

Bocquet

Sautet

et al. 2003

Chemical Physics Letters

118

121

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“…Rovida et al have proposed that the restructured silver surface is stable only in the presence of adsorbed oxygen. 36 Consequently, as more subsurface oxygen is removed at higher reduction temperatures, the silver surface will tend to show the close-packed plane with lowest surface energy. Again, reduction temperature determines the extent to which the silver catalyst will deactivate.…”

Section: Surface Restructuring and Redispersion Of Silver Particlesmentioning

confidence: 99%

Restructuring and Redispersion of Silver on SiO₂ under Oxidizing/Reducing Atmospheres and Its Activity toward CO Oxidation

et al. 2005

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The effects of oxygen-hydrogen pretreatments of nanosilver catalysts in cycle mode on the structure and particle size of silver particles, and subsequently the activity of the catalyst toward CO oxidation (or CO selective oxidation in the presence of H 2 ), are reported in this paper. Ag/SiO 2 catalyst with silver particle sizes of ca. 6∼8 nm shows relatively high activity in the present reaction system. The adopting of a cycle of oxidation/reduction pretreatment has a marked influence on the activity of the catalyst. Oxygen pretreatment at 500°C results in the formation of subsurface oxygen and activates the catalyst. As evidenced by in-situ XRD and TEM, the following H 2 treatment at low temperatures (100∼300°C) causes surface faceting and redispersing of the silver particles without destroying the subsurface oxygen species. The subsequent in-situ FTIR and catalytic reaction results show that CO oxidation occurs at -75°C and complete CO conversion can be obtained at 40°C over such a nanosilver catalyst pretreated with oxygen at 500°C followed by H 2 at 100°C. However, prolonged hydrogen treatment at high temperatures (>300°C) after oxygen pretreatment at 500°C induces the aggregation of silver particles and also depletes so much subsurface oxygen species that the pathway of CO oxidation by the subsurface oxygen species is inhibited. Meanwhile, the ability of the catalyst to adsorb reactants is greatly depressed, resulting in a 20∼30% decrease in the activity toward CO oxidation. However, the activity of the catalyst pretreated with oxygen at 500°C followed by hydrogen treatment at high temperatures (>300°C) is still higher than that directly pretreated with H 2 . This kind of catalytic behavior of silver catalyst is associated with physical changes in the silver crystallites because of surface restructuring and crystallite redispersion during the course of oxygen-hydrogen pretreatment steps.

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“…Of the oxygen induced Ag surface reconstructions, the p(4×4) reconstruction of the (111) surface has been the most widely studied and is believed to be the most stable structure under conditions relevant for EO catalysis (10,35 (36)(37). Over the next thirty years, a variety of models for a p(4×4)-O/Ag structure were proposed and subsequently improved upon (38).…”

Section: Introductionmentioning

confidence: 99%

Thermally Selective Formation of Subsurface Oxygen in Ag(111) and Consequent Surface Structure

et al. 2016

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Derouin, Jonathan; Farber, Rachael G.; Turano, Marie E.; Iski, Erin V.; and Killelea, Daniel. Thermally Selective Formation of Subsurface Oxygen in Ag(111) Just Accepted "Just Accepted" manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides "Just Accepted" as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. "Just Accepted" manuscripts appear in full in PDF format accompanied by an HTML abstract. "Just Accepted" manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). "Just Accepted" is an optional service offered to authors. Therefore, the "Just Accepted" Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the "Just Accepted" Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these "Just Accepted" manuscripts. Thermally Selective Formation of Subsurface Oxygen inAg (111) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 AbstractA long-standing challenge in the study of heterogeneously catalyzed reactions on silver surfaces has been the determination of what oxygen species are of greatest chemical importance.This is due to the coexistence of several different surface phases on oxidized silver surfaces. A further complication is subsurface oxygen (O sub ). O sub are O atoms absorbed into the near surface of a metal, and are expected to alter the surface in terms of chemistry and structure, but these effects have yet to be well characterized. We studied oxidized Ag(111) surfaces after exposure to gas-phase O atoms to determine how O sub is formed and how its presence alters the resultant surface structure. Using a combination of surface science techniques to quantify O sub formation and the resultant surface structure, we observed that once 0.1 ML of O sub has formed, the surface dramatically, and uniformly, reconstructed to a striped phase at the expense of all other surface phases. Furthermore, O sub formation was hindered at temperatures above 500 K.The thermal dependence for O sub formation suggests that at industrial catalytic conditions of 475 -500 K for the epoxidation of ethylene-to-ethylene oxide, O sub would be present and is a factor in the subsequent reactivit...

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Chemisorption of oxygen on the silver (111) surface

Cited by 179 publications

References 30 publications

Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{1 1 1}

Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{1 1 1}

Restructuring and Redispersion of Silver on SiO₂ under Oxidizing/Reducing Atmospheres and Its Activity toward CO Oxidation

Thermally Selective Formation of Subsurface Oxygen in Ag(111) and Consequent Surface Structure

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Chemisorption of oxygen on the silver (111) surface

Cited by 179 publications

References 30 publications

Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{1 1 1}

Structures and thermodynamic phase transitions for oxygen and silver oxide phases on Ag{1 1 1}

Restructuring and Redispersion of Silver on SiO2 under Oxidizing/Reducing Atmospheres and Its Activity toward CO Oxidation

Thermally Selective Formation of Subsurface Oxygen in Ag(111) and Consequent Surface Structure

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Restructuring and Redispersion of Silver on SiO₂ under Oxidizing/Reducing Atmospheres and Its Activity toward CO Oxidation