The effect of water on the formation of strongly bound oxygen on silver surfaces

Bao, Xinhe; Mühler, Martin; Pettinger, Bruno; Uchida, Yuji; Lehmpfuhl, G.; Schlögl, Robert; Ertl, G.

doi:10.1007/bf00806112

Cited by 75 publications

(68 citation statements)

References 22 publications

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“…16 Later, Schlo¨gl and co-workers devoted special attention to the interaction of oxygen with silver at high temperatures, which would be more representative of real catalysts under methanol oxidation conditions. [17][18][19][20][21][22][23][24][25][26][27] In contrast to the static description obtained by the classical surface science approach, a very dynamic picture emerged from this series of studies with a strong interplay between oxygen incorporation in the sub-surface and bulk with structural and morphological changes in the silver, which ultimately modifies the oxygen species present at the surface. Systematic theoretical studies based on density function theory calculations were performed by the group of Scheffler.…”

Section: Introductionmentioning

confidence: 95%

The silver–oxygen system in catalysis: new insights by near ambient pressure X-ray photoelectron spectroscopy

Rocha

Oestereich

Demidov

et al. 2012

Phys. Chem. Chem. Phys.

135

169

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We addressed the interaction of oxygen with silver by synchrotron based near ambient pressure X-ray photoelectron spectroscopy at temperatures relevant for industrial oxidation reactions performed with silver catalysts. For silver single crystals, polycrystalline foils and powders in equilibrium with gas phase O 2 , we observed the dynamics of the formation of five different atomic oxygen species with relative abundances depending on the temperature and time. Correlation of their formation kinetics with spectroscopic features and thermal stability indicates that these are distinct species with different electronic structures, which might relate to the different roles of silver in oxidation reactions.

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Section: Introductionmentioning

confidence: 95%

The silver–oxygen system in catalysis: new insights by near ambient pressure X-ray photoelectron spectroscopy

Rocha

Oestereich

Demidov

et al. 2012

Phys. Chem. Chem. Phys.

135

169

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“…TEM, XPS and AES studies looking at the cross section of an oxidising Cu(100) single crystal under low oxygen partial pressure 115,161,241,242 have revealed that the oxide islands form on top of an oxide wetting layer. The wetting layer itself has a ( √ 2 × 2 √ 2)R45 • missing row reconstruction and forms In general, when a metal is capable of forming uniform subsurface oxides (as in the case of Ag(110) 243 and Ru(0001) 244 ), oxide growth proceeds uniformly, rather than via island formation. The reason for the island formation on top of the wetting layer is found in stress mismatch between the Cu(100) substrate and the Cu 2 O(100) film 161 .…”

Section: Oxide Nano-islands: Cu(100)mentioning

confidence: 99%

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Gattinoni

Michaelides

2015

Surface Science Reports

244

238

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The oxidation and corrosion of metals are fundamental problems in materials science and technology that have been studied using a large variety of experimental and computational techniques. Here we review some of the recent studies that have led to significant advances in our atomic-level understanding of copper oxide, one of the most studied and better understood metal oxides. We show that a good atomistic understanding of the physical characteristics of cuprous (Cu 2 O) and cupric (CuO) oxide and of some key processes of their formation has been obtained. Indeed, the growth of the oxide has been proven to be epitaxial with the surface and to proceed, in most cases, through the formation of oxide nano-islands which, with continuous oxygen exposure, grow and eventually coalesce. We also show how electronic structure calculations have become increasingly useful in helping to characterise the structures and energetics of various Cu oxide surfaces. However a number of challenges remain. For example, it is not clear under which conditions the oxidation of copper in air at room temperature (known as native oxidation) leads to the formation of a cuprous oxide film only, or also of a cupric overlayer. Moreover, the atomistic details of the nucleation of the oxide islands are still unknown. We close our review with a perspective on future work and discuss how recent advances in experimental techniques, bringing greater temporal and spatial resolution, along with improvements in the accuracy, realism and timescales achievable with computational approaches make it possible for these questions to be answered in the near future.

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“…This is caused either by higher oxygen loading, resulting in less charge donation from silver to  * molecular orbital of adsorbed The bands at 870-875 cm -1 could be associated to the bending vibration of Ag-OH hydroxyl groups [42,78] generated in the presence of ppm amounts of H 2 O in the gas flow, while the low frequency bands at 470-475 cm -1 fail in the region of the Ag-O stretching vibration that can be attributed to atomic oxygen species. [39,46] On the other hand, the bands at 338, 603-604 and 790-802 cm -1 observed on Ag(100) at 200ºC and on Ag(111) at 250ºC are associated to subsurface oxo-species and to surface oxygen species (labeled O) stabilized by the presence of subsurface oxygen, [39,[45][46]48] and indicate that oxygen diffusion into the bulk takes place on Ag(100) at a much lower temperature than on Ag(111) facet.…”

Section: Oxygen Activation On Ag(100) and Ag(111) Catalystsmentioning

confidence: 99%

“…[31][32] Direct propylene epoxidation by molecular oxygen over silver-based catalysts has also been investigated [6,[38][39][40][41][42][43][44][45][46][47][48][49][50] but, since conventionally synthesized catalysts are highly polycrystalline -exhibiting several crystallographic facets and showing broad particle size distribution-, a detailed understanding of the nature of the selective active sites becomes a quite challenging task. It is therefore of interest to gain an atomistic view of the catalytic centers and of the reaction mechanism by means of theoretical calculations.…”

Section: Introductionmentioning

confidence: 99%

Aerobic epoxidation of propene over silver (111) and (100) facet catalysts

Pulido

Concepción

Boronat

et al. 2012

Journal of Catalysis

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Academic Press; ElsevierPulido Junquera, MA.; Concepción Heydorn, P.; Boronat Zaragoza, M.; Corma Canós, A. (2012). Aerobic epoxidation of propene over silver (111) and (100) AbstractCatalytic performance of single crystal Ag(100) and Ag(111) catalysts for propene oxidation has been investigated by means of Raman spectroscopy and mass spectrometry, and the energy profile has been obtained at the DFT-D level. It has been theoretically found, and confirmed by Raman spectroscopy, that Ag(100) surface is more reactive towards O 2 dissociation than Ag(111), and that adsorbed oxo-species are more strongly bonded to the Ag(100) facet. The higher selectivity towards propylene oxide (PO) observed for the Ag(100) catalyst can be rationalized from theoretical calculations indicating that the activation barriers for formation of the allylic intermediate -precursor of combustion products-are rather similar on both silver surfaces, whereas energy barriers on the reaction pathways for formation of PO and carbonylic products (acetone and propanal) are systematically smaller on the Ag (100) surface.

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The effect of water on the formation of strongly bound oxygen on silver surfaces

Cited by 75 publications

References 22 publications

The silver–oxygen system in catalysis: new insights by near ambient pressure X-ray photoelectron spectroscopy

The silver–oxygen system in catalysis: new insights by near ambient pressure X-ray photoelectron spectroscopy

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

Aerobic epoxidation of propene over silver (111) and (100) facet catalysts

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