Voltage-dependent ordering of water molecules at an electrode–electrolyte interface

Toney, Michael F.; Howard, Jason N.; Richer, Jocelyn; Borges, Gary L.; Gordon, Judith R.; Melroy, Owen R.; Wiesler, David G.; Yee, Dennis; Sorensen, L. B.

doi:10.1038/368444a0

Cited by 591 publications

(529 citation statements)

References 22 publications

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“…It should be noted that the hydrogen-end down structure for adsorbed water is stable up until about +0.1 V. At higher potentials, water is oriented with its oxygen end toward the surface. This change in water structure as a function of potential is known as the water flip-flop mechanism (also found for water over Pd 1 and with molecular dynamics simulations 28 and cluster calculations 29 and X-ray surface studies by Toney 30 ). The adsorption energy of the water layer is calculated as follows: ∆E water layer ( ) ) E total ( ) -E slab -( ) -E slab -4E water in a vacuum , where E total ( ) is the total energy of the water covered surface, E slab ( ) + E slab denotes the total energy of the clean surface at a given field strength, and E water in a vacuum is the energy of a water molecule in a vacuum.…”

Section: Resultsmentioning

confidence: 70%

Calculated Phase Diagrams for the Electrochemical Oxidation and Reduction of Water over Pt(111)

Rossmeisl¹,

Nørskov²,

Taylor³

et al. 2006

J. Phys. Chem. B

416

459

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Ab initio density functional theory is used to calculate the electrochemical phase diagram for the oxidation and reduction of water over the Pt(111) surface. Three different schemes proposed in the literature are used to calculate the potential-dependent free energy of hydrogen, water, hydroxyl, and oxygen species adsorbed to the surface. Despite the different foundations for the models and their different complexity, they can be directly related to one another through a systematic Taylor series expansion of the Nernst equation. The simplest model, which includes the potential only as a shift in the chemical potential of the electrons, accounts very well for the thermochemical features determining the phase-diagram.

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Section: Resultsmentioning

confidence: 70%

Calculated Phase Diagrams for the Electrochemical Oxidation and Reduction of Water over Pt(111)

Rossmeisl¹,

Nørskov²,

Taylor³

et al. 2006

J. Phys. Chem. B

416

459

View full text Add to dashboard Cite

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“…Water molecules at electrode/electrolyte interfaces reorient from "oxygen-up" to "oxygen-down" as the potential on the electrode changes from negative to positive [11][12][13][14]. Another extensively studied system is pyridine adsorbed on gold electrodes [15,16].…”

Section: Pacs Numbersmentioning

confidence: 99%

Nanoscopic Friction under Electrochemical Control

et al. 2014

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We propose a theoretical model of friction under electrochemical conditions focusing on the interaction of a force microscope tip with adsorbed polar molecules of which the orientation depends on the applied electric field. We demonstrate that the dependence of friction force on the electric field is determined by the interplay of two channels of energy dissipation: (i) the rotation of dipoles and (ii) slips of the tip over potential barriers. We suggest a promising strategy to achieve a strong dependence of nanoscopic friction on the external field based on the competition between long range electrostatic interactions and short range chemical interactions between tip and adsorbed polar molecules. PACS numbers:Control of friction during sliding is extremely important for a large variety of applications [1,2]. A unique path to control and ultimately manipulate the forces between material surfaces is through an applied electric field. By varying the applied potential, the electrode surface can quickly and reversibly be modified either with adsorbed (sub)monolayer or multilayers, or via the oxidation and reduction of surfaces, or deposition of ultrathin films [3,4]. Thus, friction force microscopy (FFM) measurements under electrochemical conditions [5-10] may offer significant advantages in comparison to those between dry surfaces.Several experimental and theoretical studies of electrochemical interfaces demonstrated that the orientation of polar molecules adsorbed at electrode surfaces is potential dependent. Water molecules at electrode/electrolyte interfaces reorient from "oxygen-up" to "oxygen-down" as the potential on the electrode changes from negative to positive [11][12][13][14]. Another extensively studied system is pyridine adsorbed on gold electrodes [15,16]. Recent FFM measurements combined with cyclic voltammetry [17] have shown that friction depends strongly on the orientation of the molecules and is five times higher when the molecules are parallel to the substrate compared to their vertical orientation. The molecule orientation can be changed either by changing their concentration or by an external field. In the latter case, the friction shows an intense peak around values of the field where the change of orientation takes place. Recent FFM measurements in UHV have also shown strong sensitivity of nanoscopic friction to the orientation of surface molecules [18]. Investigating the impact of potentialdependent orientation of adsorbed molecules on friction offers a new perspective on active control of friction forces through reversible molecular reorientation.In spite of the first successful experimental studies of nanoscopic friction under potential control [5][6][7][8][9][10], so far there have been no theoretical or numerical studies of the effect of electric fields on friction. We do not know what the mechanism is behind the observed variation of friction with electrostatic potential, nor in which systems significant reversible variation of the friction can be achieved.In this Letter we propose a m...

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“…[12][13][14][15][16][17] Other comparable studies have been of electrode-electrolyte interfaces under potentiometric control. [18][19][20] Thus we can begin to compare trends in the near-surface water structures among these different systems.…”

Section: Introductionmentioning

confidence: 99%

Structure of Barite (001)− and (210)−Water Interfaces

et al. 2001

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The structures of the barite (001) and (210) cleavage surfaces were measured in contact with deionized water at 25°C. High resolution (∼1 Å) specular X-ray reflectivity and atomic force microscopy were used to probe the step structures of the cleaved surfaces and the atomic structures of the barite-water interfaces including the structures of water near the barite-water interfaces. The barite (001) and (210) cleavage surfaces are characterized by large (>2500 Å) domains separated by unit-cell steps (7.15 and 3.44 Å steps for the (001) and (210) surfaces, respectively). This observation was unanticipated for the (001) surface in which adjacent BaSO 4 layers are displaced vertically by c/2 and symmetry related through a 2 1 screw axis along (001). The atomic structures of the two cleavage surfaces derived by X-ray reflectivity reveal that near-surface sulfate groups exhibit significant (∼0.4 Å) structural displacements, while Ba surface ion displacements are significantly smaller (∼0.07 Å). Water adsorbs to the barite surfaces in a manner consistent, in both number and height, with the saturation of broken Ba-O bonds; no evidence was found for additional structuring of the fluid water near the surface.

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Voltage-dependent ordering of water molecules at an electrode–electrolyte interface

Cited by 591 publications

References 22 publications

Calculated Phase Diagrams for the Electrochemical Oxidation and Reduction of Water over Pt(111)

Calculated Phase Diagrams for the Electrochemical Oxidation and Reduction of Water over Pt(111)

Nanoscopic Friction under Electrochemical Control

Structure of Barite (001)− and (210)−Water Interfaces

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