Interaction of water with clean and gold-precovered tungsten field emitters: adsorption and desorption

Bryl, Robert; Błaszczyszyn, R.; Galewska, Ewa

doi:10.1016/s0042-207x(96)00283-7

Cited by 9 publications

(3 citation statements)

References 14 publications

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“…Water adsorption on W(111) also was investigated for various modified W(111) surfaces using temperature-programmed desorption (TPD) and highresolution electron energy loss spectroscopy (HREELS) methods. 16 Bryl and co-workers 17 studied the interaction of water with clean and gold-precovered W field emitters and have shown that water decomposes on clean W(111), producing surface oxygen and hydrogen gas. To our best knowledge, there is no theoretical study of water decomposition on W(111).…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Dissociation of H₂O on a W(111) Surface: A Computational Study

Chen

Musaev

Lin³

2007

J. Phys. Chem. C

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The adsorption and dissociation of water on a W(111) surface have been studied at the density functional theory (DFT) level in conjunction with the projected augmented wave approach. The potential energy surface of the water decomposition on the W(111) surface was constructed. It was shown that the barriers for the stepwise H 2 O dehydrogenation reaction, H 2 O f 2H (ads) + O (ads) , are 1.8 (for HO-H bond activation) and 15.9 (for the O-H bond activation) kcal/mol. The entire process, W(111) + H 2 O f 2H (ads) + O (ads) , is 54.4 kcal/mol exothermic. Calculations show that the formation of W(111)-O + H 2(gas) from W(111) + H 2 O is also exothermic by 23.7 kcal/mol. These results are in good agreement with the temperature-programmed desorption and high-resolution electron energy loss spectroscopy data. On the basis of the calculated PES, we predicted kinetic rate constants for the dissociative adsorption of H 2 O on the W(111) surface. The structure, vibrational frequency, and binding energy of the W(111)-H 2 O, W(111)-OH, W(111)-O, and W(111)-H systems were also predicted. It was shown that the most favorable structure of W( 111)-H 2 O corresponds to the coordination of water through its oxygen lone pairs with the W( 111) surface (at its top position). The preferable binding sites for the OH, O, and H fragments are top, top, and bridge sites, respectively. The stepwise dissociative adsorption mechanism of H 2 O on the W(111) surface has also been confirmed by DFT molecular dynamics simulations.

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Section: Introductionmentioning

confidence: 99%

Adsorption and Dissociation of H₂O on a W(111) Surface: A Computational Study

Chen

Musaev

Lin³

2007

J. Phys. Chem. C

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“…As in the previous work, the ramped field data of Stintz and Panitz show ionization of water−ice to form hydrated protons with typically three water molecules per cluster. Other field ionization and field emission studies of water include measurements of ion energy deficits for ionization at rhodium tips, photon-stimulated field ionization of water, , real-time field ionization imaging of the hydrogen/oxygen reaction on a platinum tip, , and field emission microscopy of water layers. , …”

Section: Introductionmentioning

confidence: 99%

Electric Field Effects in Ionization of Water−Ice Layers on Platinum

et al. 1999

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Field ionization of water−ice adsorbed onto a platinum field emitter tip of radius 350 Å was studied as a function of temperature over the range of temperature 80−145 K and of water layer thickness 100−3000 Å. The water adlayer was grown under field-free conditions by exposure to water vapor in ultrahigh vacuum. Field ionization was probed by ramped field desorption (RFD), in which desorption of ionic species (hydrated protons) is measured while increasing the applied electric field linearly in time. The dependence of the field required for onset of ionization as a function temperature and thickness is presented and discussed. In the limit of thin water layers, the onset field of ionization decreased from 0.6 to 0.3 V/Å with temperature increasing from 80 to 145 K. An activation barrier of 0.75 eV for ionization of water to produce hydrated protons and hydroxide ions was estimated from the temperature dependence of the onset field. The onset field increased with water layer thickness, and a break point in the slope of onset field versus thickness was interpreted as a transition in the ionization location from the water−vacuum interface to the tip−water interface. The relevance of these experiments in simulating electrode−electrolyte interfaces is discussed.

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“…Pure gold samples are routinely prepared by electrochemical etching of a gold wire using KCN solutions, but also in CaCl2, NaCl, KCl, and H2SO4 + HNO3 solutions [130][131][132][133][134]. Alternatively, inert metallic tips such as tungsten can be prepared and then covered with a few atomic layers of Au by vacuum evaporation or laser deposition [135][136][137]. In the case of alloys, the samples are prepared either by electrochemical etching of the alloy wire [138], or by evaporation of the two metals followed by annealing to ensure the homogenisation of the alloy-layer [139].…”

Section: Field Emission Microscopy Fem/field Ion Microscopy Fimmentioning

confidence: 99%

Dynamic Processes on Gold-Based Catalysts Followed by Environmental Microscopies

et al. 2017

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Abstract:Since the early discovery of the catalytic activity of gold at low temperature, there has been a growing interest in Au and Au-based catalysis for a new class of applications. The complexity of the catalysts currently used ranges from single crystal to 3D structured materials. To improve the efficiency of such catalysts, a better understanding of the catalytic process is required, from both the kinetic and material viewpoints. The understanding of such processes can be achieved using environmental imaging techniques allowing the observation of catalytic processes under reaction conditions, so as to study the systems in conditions as close as possible to industrial conditions. This review focuses on the description of catalytic processes occurring on Au-based catalysts with selected in situ imaging techniques, i.e., PEEM/LEEM, FIM/FEM and E-TEM, allowing a wide range of pressure and material complexity to be covered. These techniques, among others, are applied to unravel the presence of spatiotemporal behaviours, study mass transport and phase separation, determine activation energies of elementary steps, observe the morphological changes of supported nanoparticles, and finally correlate the surface composition with the catalytic reactivity.

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Interaction of water with clean and gold-precovered tungsten field emitters: adsorption and desorption

Cited by 9 publications

References 14 publications

Adsorption and Dissociation of H₂O on a W(111) Surface: A Computational Study

Adsorption and Dissociation of H₂O on a W(111) Surface: A Computational Study

Electric Field Effects in Ionization of Water−Ice Layers on Platinum

Dynamic Processes on Gold-Based Catalysts Followed by Environmental Microscopies

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Interaction of water with clean and gold-precovered tungsten field emitters: adsorption and desorption

Cited by 9 publications

References 14 publications

Adsorption and Dissociation of H2O on a W(111) Surface: A Computational Study

Adsorption and Dissociation of H2O on a W(111) Surface: A Computational Study

Electric Field Effects in Ionization of Water−Ice Layers on Platinum

Dynamic Processes on Gold-Based Catalysts Followed by Environmental Microscopies

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Product

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Adsorption and Dissociation of H₂O on a W(111) Surface: A Computational Study

Adsorption and Dissociation of H₂O on a W(111) Surface: A Computational Study