Water-induced surface reconstruction of oxygen<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>covered Ru(0001)

Maier, Sabine; Cabrera-Sanfélix, Pepa; Stass, Ingeborg; Sánchez‐Portal, Daniel; Arnau, A.; Salmerón, Miquel

doi:10.1103/physrevb.82.075421

Cited by 12 publications

(9 citation statements)

References 39 publications

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“…The diffusion rate drops to <0.01 s −1 at 250 K and order 10 −5 s −1 at 200 K. This suggests that the surface oxygen layer is unlikely to equilibriate over experimental time periods at temperatures of much less than room temperature. This confirms that a lack of surface oxygen mobility is the reason that equilibrium defect concentrations expected for around 200−300 K were observed on STM conducted at 7 K. 16 3.3. Formamide Adsorption to a Ru (0001) Surface with Perfectly Ordered Oxygen Overlayer.…”

Section: Resultssupporting

confidence: 85%

First-Principles Study of the Formamide Adsorption to the Oxygen-Covered (0001) Surface of Ruthenium

McGill

Söhnel

2012

J. Phys. Chem. C

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Density functional theory has been used to study the adsorption of formamide over the (0001) surface of ruthenium metal with a coadsorbed oxygen (1 × 2) overlayer. Molecular adsorption is found to be energetically preferred and in the case of a perfectly ordered oxygen overlayer proceeds mainly through hydrogen bonding between the amino hydrogen and surface oxygen as well as some weak coordinate bonding between the carbonyl oxygen and surface ruthenium. The most energetically favored dissociative mode is found to involve the transfer of a proton to metal HCP sites and coordinate bonding between both the formamide N and O atoms and surface Ru. The resulting adsorption energies are found to be too small to explain experimental desorption temperatures but may be improved somewhat by the inclusion of an empirical dispersion correction. The effect of vacancies and disorder in the oxygen overlayer on formamide adsorption has also been investigated. It is found that disorder in the oxygen overlayer yields higher adsorption energies and may explain a number of experimental observations.

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Section: Resultssupporting

confidence: 85%

First-Principles Study of the Formamide Adsorption to the Oxygen-Covered (0001) Surface of Ruthenium

McGill

Söhnel

2012

J. Phys. Chem. C

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“…1,6,54−56 At higher O coverage, when all top sites are blocked, water adsorption causes a shift of half of the oxygen atoms from hcp sites to fcc sites, creating a honeycomb structure where water molecules bind strongly to the exposed Ru atoms. 6 The energy cost of reconstructing the oxygen overlayer is more than compensated by the larger adsorption energy of water on the newly exposed Ru atoms.…”

Section: ■ Water−oxygen Interaction: From Coadsorbed Oxygen To Oxidesmentioning

confidence: 99%

“…Many coadsorption studies have been carried out with traditional surface science techniques, in particular water coadsorbed with alkalis, O, and CO. 10 On Ru(0001), preadsorbed oxygen was found to result in a stronger binding of H 2 O, owing to the formation of hydrogen bonds between the molecule and the chemisorbed oxygen. 1,6,53,54 At the same time, the surface oxygen changes the chemical state of adsorbed water through strong H-bonding and can promote water dissociation. 55,56 STM and XPS experiments have shown that the presence of oxygen vacancies in the O(2 × 2)/Ru(0001) is necessary for H 2 O dissociation to occur.…”

Section: ■ Water−oxygen Interaction: From Coadsorbed Oxygen To Oxidesmentioning

confidence: 99%

How Does Water Wet a Surface?

2015

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The adsorption and reactions of water on surfaces has attracted great interest, as water is involved in many physical and chemical processes at interfaces. On metal surfaces, the adsorption energy of water is comparable to the hydrogen bond strength in water. Therefore, the delicate balance between the water-water and the water-metal interaction strength determines the stability of water structures. In such systems, kinetic effects play an important role and many metastable states can form with long lifetimes, such that the most stable state may not reached. This has led to difficulties in the theoretical prediction of water structures as well as to some controversial results. The direct imaging using scanning tunneling microscopy (STM) in ultrahigh vacuum at low temperatures offers a reliable means of understanding the local structure and reaction of water molecules, in particular when interpreted in conjunction with density functional theory calculations. In this Account, a selection of recent STM results on the water adsorption and dissociation on close-packed metal surfaces is reviewed, with a particular focus on Ru(0001). The Ru(0001) surface is one where water adsorbs intact in a metastable state at low temperatures and where partially dissociated layers are formed at temperatures above ∼150 K. First, we will describe the structure of intact water clusters starting with the monomer up to the monolayer. We show that icelike wetting layers do not occur on close-packed metal surfaces but instead hydrogen bonded layers in the form of a mixture of pentagonal, hexagonal, and heptagonal molecular rings are observed. Second, we will discuss the dissociation mechanism of water on Ru(0001). We demonstrate that water adsorption changes from dissociative to molecular as a function of the oxygen preadsorbed on Ru. Finally, we briefly review recent STM experiments on bulk ice (Ih and Ic) and water adsorption on insulating thin films. We conclude with an outlook illustrating the manipulation capabilities of STM in respect to probe the proton and hydrogen dynamics in water clusters.

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“…In contrast, Kolb et al [47] observed that water remains intact on (111) honeycomb structure such that water molecules bind strongly to the exposed Ru atoms. [54] DFT revealed that the energy cost of reconstructing the oxygen overlayer is more than compensated by the adsorption energy of water on the newly exposed Ru atoms.…”

Section: Formation Of the First Water Layermentioning

confidence: 99%

Water at surfaces and interfaces: From molecules to ice and bulk liquid

Shimizu

Maier

Verdaguer

et al. 2018

Progress in Surface Science

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The structure and growth of water films on surfaces is reviewed, starting from single molecules, two-dimensional wetting layers, and liquid interfaces. This progression follows the increase in temperature and vapor pressure environmental conditions from a few degrees Kelvin in ultra-high vacuum, where Scanning Tunneling and Atomic Force Microscopies (STM and AFM) provide crystallographic information at the molecular level, to ambient conditions where surface sensitive spectroscopic techniques provide electronic structure information. We show how single molecules bind to metal and non-metal surfaces, their diffusion and aggregation. We examine how water molecules can be manipulated by the STM tip via excitation of vibrational and electronic modes, which trigger molecular diffusion and dissociation. We review also the adsorption and structure of water on non-metal substrates including mica, alkali halides, and others under ambient humid conditions. We finally review recent progress in the exploration of the molecular level structure of solid-liquid interfaces, which impact our fundamental understanding of corrosion and electrochemical processes. variety of names: atomic force microscopy (AFM) and its variants of contact and non-contact), lateral friction, and attractive electrostatic force microscopies, known as scanning polarization force microscopy (SPFM) and Kelvin Probe Force Microscopy (KPFM). The non-contact attractive AFM modes allow us to observe water films formed on solids with minimal disruption. We will first discuss adsorption configurations, diffusion, aggregation, and dissociation of water on metal surfaces induced thermally, vibrationally and electronically using STM. These topics were reviewed also by Hodgson and Haq in 2009 [3] from the theoretical point of view. We then move to formation of larger clusters and monolayers. The discussion of the "ice" layers is followed by liquid water films minerals (salts, oxides) in ambient conditions. In the last section, we also review recent studies of liquid water near a solid, electrified surface. Here the knowledge obtained from X-ray absorption spectroscopy (XAS) has proved useful for better understanding of atomistic pictures of electrochemical processes. Single molecules: diffusion, aggregation, dissociation Water on metal surfaces at low coverage-monomers and small clusters STM studies of adsorption of water on metal surfaces started in the early 2000's, with noble metals, including Au, Ag, Cu, and more reactive transition metals, such as Pt, Pd, Rh, Ru have been used as substrates. The first observation of individual water molecules was reported in 2001 by Lauhon and Ho [4] on Cu(001) using low-temperature STM. They pointed out several phenomena occurring during imaging of adsorbed water: 1) stable clusters form at relatively low coverage, 2) imaging of small clusters (less than 6 molecules) often leads to the tip inducing molecular motions, and 3) large clusters have internal structures that are often difficult to resolve. Morgenstern et al. [5-9] st...

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Water-induced surface reconstruction of oxygen(2×1)covered Ru(0001)

Cited by 12 publications

References 39 publications

First-Principles Study of the Formamide Adsorption to the Oxygen-Covered (0001) Surface of Ruthenium

First-Principles Study of the Formamide Adsorption to the Oxygen-Covered (0001) Surface of Ruthenium

How Does Water Wet a Surface?

Water at surfaces and interfaces: From molecules to ice and bulk liquid

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