Adsorption of Water on Cu2O and Al2O3 Thin Films

Deng, Xingyi; Herranz, T.; Weis, Christoph; Bluhm, Hendrik; Salmerón, Miquel

doi:10.1021/jp800944r

Cited by 132 publications

(166 citation statements)

References 32 publications

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“…Similar studies have been conducted on copper oxide and aluminum oxide. These studies found that adsorbed water will react with lattice oxygen to form OH and that this reaction is completed by ~1% RH [44]. Increasing RH beyond this point results in an adsorbed water layer that reaches a monolayer near 15% RH and about 6 layers at 90% RH [44].…”

Section: Environmental Effect On Friction and Wear Of Metalsmentioning

confidence: 97%

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

et al. 2015

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Tribology involves not only two-body contacts of two solid materials-a substrate and a counter-surface; it often involves three-body contacts whether the third body is intentionally introduced or inevitably added during the sliding or rubbing. The intentionally added third body could be lubricant oil or engineered nanomaterial used to mitigate the friction and wear of the sliding contact. The inevitably added third body could be wear debris created from the substrate or the counter surface during sliding. Even in the absence of any solid third-body between the sliding surfaces, molecular adsorption of water or organic vapors from the surrounding environment can dramatically alter the friction and wear behavior of solid surfaces tested in the absence of lubricant oils. This review article covers the last case: the effects of molecular adsorption on sliding solid surfaces both inevitably occurring due to the ambient test and intentionally introduced as a solution for engineering problems. We will review how adsorbed molecules can change the course of wear and friction, as well as the mechanical and chemical behavior, of a wide range of materials under sliding conditions.

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Section: Environmental Effect On Friction and Wear Of Metalsmentioning

confidence: 97%

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

et al. 2015

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“…This is based on reports by other groups on the interaction of water vapor with the surfaces of various metal oxides including SiO 2 . 28,[32][33][34][35] In these studies, it was argued that the hydroxylation precedes the growth of a molecular water film, and the former starts at an RH of much lower than 1%. After the saturation of hydroxyl formation at a RH of around 1%, the adsorption of molecular water begins as a result of the attractive interaction between H 2 O molecules and hydroxyls.…”

Section: B Ap-xps Experimentsmentioning

confidence: 99%

Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

Mori

Oka

Hosoi

et al. 2016

Journal of Applied Physics

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The energy difference between the oxide and bulk peaks in X-ray photoelectron spectroscopy (XPS) spectra was investigated for both GeO 2 /Ge and SiO 2 /Si structures with thickness-controlled water films. This was achieved by obtaining XPS spectra at various values of relative humidity (RH) of up to $15%. The increase in the energy shift is more significant for thermal GeO 2 on Ge than for thermal SiO 2 on Si above $10 À4 % RH, which is due to the larger amount of water molecules that infiltrate into the GeO 2 film to form hydroxyls. Analyzing the origins of this energy shift, we propose that the positive charging of a partially hydroxylated GeO 2 film, which is unrelated to X-ray irradiation, causes the larger energy shift for GeO 2 /Ge than for SiO 2 /Si. A possible microscopic mechanism of this intrinsic positive charging is the emission of electrons from adsorbed water species in the suboxide layer of the GeO 2 film to the Ge bulk, leaving immobile cations or positively charged states in the oxide. This may be related to the reported negative shift of flat band voltages in metaloxide-semiconductor diodes with an air-exposed GeO 2 layer. Published by AIP Publishing.

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“…It is known that OH is readily formed on surfaces in the presence of H 2 O pressure as low as 1 × 10 -7 torr. 19 The peak at 536.3 eV is due to the gas phase CO 2 . Interestingly, we found that in the presence of CO 2 the incident x-rays or the emitted photoelectrons induce the formation of carbonate species on the surface.…”

Section: Cu 2 O In Vacuum and In The Presence Of 01 Torr Comentioning

confidence: 99%

Surface Chemistry of Cu in the Presence of CO₂ and H₂O

et al. 2008

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The chemical nature of copper and copper oxide (Cu 2 O) surfaces in the presence of CO 2 and H 2 O at room temperature was investigated using ambient pressure x-ray photoelectron spectroscopy. The studies reveal that in the presence of 0.1 torr CO 2 several species form on the initially clean Cu, including carbonate CO 3 2 , CO 2 δ-and C 0 , while no modifications occur on an oxidized surface. The addition of 0.1 ML Zn to the Cu results in the complete conversion of CO 2 δ-to carbonate. In a mixture of 0.1 torr H 2 O and 0.1 torr CO 2 , new species are formed, including hydroxyl, formate and methoxy, with H 2 O providing the hydrogen needed for the formation of hydrogenated species.

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Adsorption of Water on Cu₂O and Al₂O₃ Thin Films

Cited by 132 publications

References 32 publications

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

Surface Chemistry of Cu in the Presence of CO₂ and H₂O

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Adsorption of Water on Cu2O and Al2O3 Thin Films

Cited by 132 publications

References 32 publications

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

Surface Chemistry of Cu in the Presence of CO2 and H2O

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Adsorption of Water on Cu₂O and Al₂O₃ Thin Films

Surface Chemistry of Cu in the Presence of CO₂ and H₂O