IR studies of the interaction of water with lanthanum oxide surfaces

Paulidou, Anastasia; Nix, Roger M.

doi:10.1016/s0039-6028(00)00857-8

Cited by 13 publications

(11 citation statements)

References 8 publications

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“…The spectrum of the 20LaA sample presents a quite sharp peak at 3715 cm -1 , with pronounced shoulders near 3780 and 3680 cm -1 . Interestingly, the spectrum does not show evident components in the region typical of La-OH groups observed on the surface of La 2 O 3 samples, typically found in the 3680-3610 cm -1 region 37,38,39,40 . In the case of the sample 80LaA, the disk has low transmission in the high frequency region, where weak bands at ca.…”

Section: Surface Characterization By Ir Spectroscopymentioning

confidence: 86%

Acido-basicity of lanthana/alumina catalysts and their activity in ethanol conversion

Garbarino

Wang

Valsamakis

et al. 2017

Applied Catalysis B: Environmental

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Lanthana on alumina samples (0.2, 0.8 and 4.7 theoretical monolayers) were prepared by incipient wetness impregnation using γ-Al2O3 as support. Characterization has been performed by BET, XRD, skeletal FT-IR, DR-UVvis, XPS, HR-TEM, IR spectra of the surface OH, adsorbed pyridine and CO2, and isopropanol TPD. Ethanol conversion was investigated both in temperature-programmed surface reaction (TPSR) dynamic conditions as well as in steady-state flow reactor tests. Lanthanum addition stabilizes alumina with respect to sintering and loss of surface area and La- containing phases are observed only for the high-La loaded catalyst. La-alumina catalysts are less active in ethanol dehydration than alumina but more selective to diethyl ether at partial conversion. 5%La2O3/Al2O3 is also equally or more selective than alumina to ethylene at high conversion, producing less carbonaceous material during reaction. Thus, this catalytic system might be a good candidate for (bio)ethylene production through (bio)ethanol dehydration

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Section: Surface Characterization By Ir Spectroscopymentioning

confidence: 86%

Acido-basicity of lanthana/alumina catalysts and their activity in ethanol conversion

Garbarino

Wang

Valsamakis

et al. 2017

Applied Catalysis B: Environmental

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“…Similarly, Paulidou and Nix have used reflection IR spectroscopy to study the adsorption of water on ordered epitaxial layers of lanthanum oxide. 14 Their study suggests the formation of two distinct types of hydroxyl groups, which differ in their coordination to the lanthanum ions thereby suggesting that adsorption is accompanied by surface reconstruction. Spectroscopic studies by Eftekhari-Bafrooei and Borguet have employed time-resolved sum frequency generation (tr-SFG) to understand the effect of hydrogen-bond strength on the vibrational relaxation of interfacial water near a silica surface.…”

Section: Introductionmentioning

confidence: 99%

“…It is therefore not surprising that the studies on atomic scale characterization of interfacial water near oxide surfaces continue to be a subject of immense scientific interest. 1,8,9,14,16,34 A detailed understanding of the molecular scale structure is necessary to exercise control over the dynamical processes occurring in the interfacial water near oxide surfaces.…”

Section: Introductionmentioning

confidence: 99%

Atomic scale characterization of interfacial water near an oxide surface using molecular dynamics simulations

Deshmukh

Sankaranarayanan

2012

Phys. Chem. Chem. Phys.

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Atomic scale characterization of the structure and dynamics of confined water molecules located near the metal oxide-aqueous interface is carried out using molecular dynamics simulations. Proximity effects on water molecules (H(2)O) near a magnesium oxide surface (MgO(100)) at room temperature are evaluated based on various structural and dynamical correlation functions. Translational and orientational order parameters are used to quantify the extent of ordering of water molecules near the oxide surface. There is significant ordering of water molecules in the two layers close to the oxide interface and the extent of ordering decreases with increasing distance from the oxide-water interface. The characteristic structural features of proximal water molecules near oxide-aqueous interfaces are strongly correlated to their vibrational densities of states. Systematic trends in libration, bending, and stretching bands are correlated with local ordering of water molecules and the hydrogen-bonding network. We find that restricted transverse oscillations result in larger blue shifts in O-O-O bending and O-O stretching bands for water molecules having increased proximity to the interface. The O-H stretching band is red-shifted whereas the libration bands for proximal water are blue shifted with respect to bulk water; the extent of shifts are sensitive to the interface proximity, their local confinement and their hydrogen bonding status.

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“…For films fabricated using O 2 and O 3 , the thickness decreased as the dipping time increased. According to other studies [10][11], upon contact with water, La 2 O 3 changes to La(OH) 3 (lanthanum hydroxide) via a hydration reaction, which dissolves well in water. The hydration reaction causes a continuous decrease the thickness of La 2 O 3 films.…”

Section: Methodsmentioning

confidence: 89%

A study on the characteristics of hydrated La2O3 thin films with different oxidation gases on the various annealing temperature

2008

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In order to investigate the structural and electrical properties of La 2 O 3 films deposited by O 2 and O 3 , films were hydrated in DI-water and annealed at 600 and 900°C. La 2 O 3 films deposited by O 3 showed better hydration resistance than those deposited by O 2 . The thickness of both hydrated films decreased after annealing at 600°C and increased after annealing at 900°C. The dielectric constants of the La 2 O 3 films deposited by O 3 were greater than films deposited by O 2 after annealing at 600°C and slightly less after annealing at 900°C. The leakage current density of the La 2 O 3 films deposited by O 3 was lower than those by O 2 after annealing at 900°C. To this end, La 2 O 3 films deposited by O 3 showed better dissolution resistance than O 2 for hydration experiment as a function of dipping time.

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IR studies of the interaction of water with lanthanum oxide surfaces

Cited by 13 publications

References 8 publications

Acido-basicity of lanthana/alumina catalysts and their activity in ethanol conversion

Acido-basicity of lanthana/alumina catalysts and their activity in ethanol conversion

Atomic scale characterization of interfacial water near an oxide surface using molecular dynamics simulations

A study on the characteristics of hydrated La2O3 thin films with different oxidation gases on the various annealing temperature

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