High-Coverage Oxygen-Induced Surface Structures on Ag(111)

Martin, Natalia; Klacar, Simon; Grönbeck, Henrik; Knudsen, Jan; Schnadt, Joachim; Blomberg, Sara; Gustafson, Johan; Lundgren, Edvin

doi:10.1021/jp504387p

Cited by 50 publications

(88 citation statements)

References 35 publications

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“…Calculations show that the several surface oxides and reconstructions have similar surface free energies, and they are more stable than O sub around 600 K (5,20,49), therefore, O sub desorbs before decomposition of the surface reconstruction. This behavior is qualitatively similar to subsurface H (H sub ) on Ni(111), where H sub is metastable with respect to adsorbed H (H ad ) and desorbs at around 100 K lower temperature than H ad (50)(51).…”

Section: Surface Temperature Effect On Oxygen Uptake On Ag(111)mentioning

confidence: 99%

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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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Section: Surface Temperature Effect On Oxygen Uptake On Ag(111)mentioning

confidence: 99%

“…Ag(111) surfaces exhibit a variety of different surface reconstructions induced by adsorbed oxygen (O ad ) (5,9), along with several other oxide species (10)(11)(12)(13)(14)(15)(16). The primary motivation to study the O/Ag(111) system is silver's importance as an industrial partial oxidation catalyst (11,17).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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“…[25][26][27][28][29]32 Other methods were also utilized for atomic oxygen delivery onto the Ag(111) surface under UHV conditions, such as NO 2 decomposition 31,36,38,40,47,50 and thermal gas cracking. 41,42,45 Ozone decomposition is an extremely efficient method for dosing high concentrations of oxygen atoms on metal surfaces under UHV conditions (i.e., in the absence of elevated-pressure exposures). Efficient atomic oxygen delivery onto single-crystal model catalyst surfaces with ozone was successfully carried out for Al(111), 51 Pd(111), 52 Pt(111), 52,53 and Au(111).…”

Section: ■ Introductionmentioning

confidence: 99%

“…33 In a related study, Martin et al deposited atomic oxygen on Ag(111) by thermal cracking of O 2 (g) at 500 K with P O 2 = 10 −7 mbar. 41 They reported bulklike silver oxide formation at high θ O and argued that the c(4×8) overlayer is the precursor state for bulklike silver oxide formation.…”

Section: ■ Introductionmentioning

confidence: 99%

Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Karatok¹,

Vovk

Koç³

et al. 2017

J. Phys. Chem. C

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Ammonia-selective catalytic oxidation was studied on the planar Ag(111) single-crystal model catalyst surface under ultra-highvacuum (UHV) conditions. A variety of oxygen species were prepared via ozone decomposition on pristine Ag(111). Surface coverages of oxygen species were quantified by temperature-programmed desorption (TPD) and X-ray photoemission spectroscopy techniques. Exposure of ozone on Ag(111) at 140 K led to a surface atomic oxygen (O a ) overlayer. Lowenergy electron diffraction experiments revealed that annealing of this atomic oxygen-covered Ag(111) surface at 473 K in UHV resulted in the formation of ordered oxide surfaces (O ox ) with p(5×1) or c(4×8) surface structures. Ammonia interactions with O/Ag(111) surfaces monitored by temperature-programmed reaction spectroscopy indicated that disordered surface atomic oxygen selectively catalyzed N−H bond cleavage, yielding mostly N 2 along with minor amounts of NO and N 2 O. Higher coverage O/Ag(111) surfaces, whose structure was tentatively assigned to a bulklike amorphous silver oxide (O bulk ), showed high selectivity toward N 2 O formation (rather than N 2 ) due to its augmented oxygen density. In contrast, ordered surface oxide overlayers on Ag(111) (where the order was achieved by annealing the oxygen adlayer to 473 K) showed only very limited reactivity toward ammonia. The nature of the adsorbed NH 3 species on a clean Ag(111) surface and its desorption characteristics were also investigated via infrared reflection absorption spectroscopy and TPD techniques. Current findings demonstrate that the Ag(111) surface can selectively oxidize NH 3 to N 2 under well-defined experimental conditions without generating significant quantities of environmentally toxic species such as NO 2 , NO, or N 2 O.

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“…Oxygen induced reconstructions of the Ag surface have been studied intensely since the 1970s when Rovida et al observed a (4 × 4) structure with LEED after high pressure O 2 dosing [24][25][26]. In the forty years since, a variety of models for a p(4 × 4)-O/Ag structure were proposed and dismissed [27]. Ultimately a model consisting of six triangles containing six Ag atoms each was proposed [21,28].…”

Section: Introductionmentioning

confidence: 99%