Ionic Properties of Vanadium Pentoxide Gels

1988 ◽  
Vol 121 ◽  
Author(s):  
J. Livage ◽  
P. Barboux ◽  
J. C. Badot ◽  
N. Baffier
Keyword(s):  
Vanadium Pentoxide ◽  
Water Adsorption ◽  
Mixed Valence ◽  
Adsorbed Water ◽  
Water Molecules ◽  
Proton Diffusion ◽  
Hydrous Oxides ◽  
Solution Interface ◽  
Ionic Devices ◽  
Acid Aqueous Medium

ABSTRACTVanadium pentoxide gels V2O5·nH2O are actually hydrous oxides. Water adsorption and dissociation occurs at the surface of the oxide leading to negatively charged oxide particles surrounded by an acid aqueous medium. Ionic conductivity is observed, arising from proton diffusion through the water molecules. This process mainly depends on the nature of adsorbed water molecules. Proton conductivity is strongly related to the water adsorption isotherm.Ion exchange readily occurs at the oxide-solution interface when the gel is dipped into an aqueous solution of a metal chloride. New vanadium bronzes have been obtained upon heating such gels around 300° C. They exhibit interesting properties as reversible cathodes.Electrochemical insertion of Li* into the gel phase is quite easy. This is due to the very open structure of the gel and the mixed valence behavior of the vanadium oxide.Transition metal oxide gels could then be used as thin films or pressed pellets for making micro-ionic devices.

Ionic Properties of Oxide Gels

1988 ◽  
Vol 135 ◽  
Author(s):  
J. Livage ◽  
P. Barboux ◽  
M. Nabavi ◽  
P. Judeinstein
Keyword(s):  
Ion Exchange ◽  
Water Adsorption ◽  
Mixed Valence ◽  
Adsorbed Water ◽  
Proton Diffusion ◽  
Hydrous Oxides ◽  
Solution Interface ◽  
Sheet Silicates ◽  
New Compounds ◽  
Ionic Devices

AbstractOxide gels are actually hydrous oxides. Water adsorption and dissociation occur at the surface of the oxide network leading to charged particles surrounded by an acid or basic aqueous medium. They can be considered as particle hydrates. Fast proton conduction is observed arising from proton diffusion through the adsorbed water layers. Proton conductivity is actually strongly related to the water adsorption isotherm.Ion exchange readily occurs at the oxide-solution interface when the gel is dipped inside an aqueous solution. Some inorganic gels exhibit a layered structure similar to that of sheet silicates. Ion exchange can then be described as an intercalation process. It can be used as a synthetic route toward new compounds.Electrochemical insertion within the oxide network is highly reversible. This is due to the open structure of the gel and the mixed valence behavior of the transition metal oxide. Reversible cathodes or electrochromic layers have been made from V2 O5, W03or TiO2gels. Thin films or pressed pellets can be easily made from oxide gels. They are therefore good candidates for making "all gel" micro-ionic devices.

Restricted Rotational Motion of InterlayerWaterMolecules in Vanadium Pentoxide Hydrate, V2O5·n D2O, as Studied by Deuterium NMR

2002 ◽  
Vol 57 (6-7) ◽  
pp. 419-424 ◽  
Author(s):  
Sadamu Takeda ◽  
Yuko Gotoh ◽  
Goro Maruta ◽  
Shuichi Takahara ◽  
Shigeharu Kittaka
Keyword(s):  
Double Layer ◽  
Vanadium Pentoxide ◽  
Rotational Motion ◽  
Interlayer Space ◽  
Layer Structure ◽  
Bond Distance ◽  
Adsorbed Water ◽  
Deuterium Nmr ◽  
Water Molecules ◽  
Layer Structures

The rotational behavior of the interlayer water molecules of deuterated vanadium pentoxide hydrate, V2O5.nD2O, was studied by solid-state deuterium NMR for the mono- and double-layer structures of the adsorbed water molecules. The rotational motion was anisotropic even at 355 K for both the mono- and double-layer structures. The 180° flipping motion about the C2-symmetry axis of the water molecule and the rotation around the figure axis, which makes an angle Ɵ with the C2-axis, occurred with the activation energy of (34±4) and (49±6) kJmol-1, respectively. The activation energies were almost independent of the mono- and double-layer structures of the water molecules, but the angle Ɵ made by the two axes varied from 33° for the monolayer to 25° for the double-layer at 230 K. The angle started to decrease above 250 K (e. g. the angle was 17 at 355 K for the double-layer structure). The results indicate that the average orientation of the water molecules in the two dimensional interlayer space depends on the layer structure and on the temperature. From the deuterium NMR spectrum at 130 K, the quadrupole coupling constant e2Qq/h = 240 kHz and the asymmetry parameter η= 0.12 were deduced. These values indicate the average hydrogen bond distance R(O H) = 2.0 Å for the D2O molecules in the 2D-interlayer space

scholarly journals Calorimetric and Spectroscopic Studies of Water Adsorption onto Alkaline Earth Fluorides

2005 ◽  
Vol 23 (6) ◽  
pp. 425-436
Author(s):  
Toshinori Mori ◽  
Yasushige Kuroda ◽  
Ryotaro Kumashiro ◽  
Koji Hirata ◽  
Hidehiro Toyota ◽  
...  
Keyword(s):  
Alkaline Earth ◽  
Water Adsorption ◽  
Adsorbed Water ◽  
Spectroscopic Studies ◽  
Water Molecules ◽  
Earth Fluoride ◽  
Alkaline Earth Fluoride ◽  
Pretreatment Temperature ◽  
Argon Adsorption ◽  
Ir Bands

Interactions between the surfaces of alkaline earth fluorides (CaF2, SrF2 and BaF2) and water molecules were investigated by calorimetric and spectroscopic methods. The exposed surfaces of the alkaline earth fluoride samples, with which the (100) crystalline plane is mainly associated, were found to be fully covered with strongly adsorbed water molecules, resulting in characteristic IR bands at 3684, 2561, 1947 and 1000 cm−1, respectively. This surface was homogeneous towards further water adsorption. The strongly adsorbed water molecules were almost completely desorbed from the surface on evacuating the sample up to 473 K. The heat of immersion in water also increased with increasing pretreatment temperature; this may be attributed to surface rehydration of the alkaline earth fluorides. The state of the surface changed drastically as the pretreatment temperature was increased and stabilized towards incoming water molecules. Thus, the surface formed after evacuation at temperatures greater than 473 K was resistant to hydration even after immersion in water at room temperature. This surface was relatively heterogeneous towards water adsorption, although it behaved homogeneously towards argon adsorption. These facts indicate that strongly adsorbed water molecules appear to be somewhat specific towards the adsorption of further incoming water molecules. The adsorption properties of the (100) plane of alkaline earth fluorides towards water and argon molecules depend strongly on both the electrostatic field strength and the extent of rehydration of the alkaline earth fluoride surface.

scholarly journals Synthesis, structure and water sorption in Zr metal-organic frameworks

2014 ◽  
Vol 70 (a1) ◽  
pp. C1240-C1240
Author(s):  
Felipe Gándara ◽  
Hiroyasu Furukawa ◽  
Zhang Yue-Biao ◽  
Juncong Jiang ◽  
Wendy Queen ◽  
...  
Keyword(s):  
Water Adsorption ◽  
Metal Organic Frameworks ◽  
Adsorbed Water ◽  
Neutron Diffraction Study ◽  
Water Molecules ◽  
Remote Areas ◽  
Adsorption Sites ◽  
Thermal Batteries ◽  
Secondary Building Units ◽  
Metal Organic

Metal-organic frameworks (MOFs) based on zirconium secondary building units (SBUs) have proven to have great thermal and chemical stability,[1,2] which make them ideal for their use in different applications. We have prepared a series of six new MOFs made from the Zr6O4(OH)4(-CO2)nsecondary building units (n = 6, 8, 10, or 12) and variously shaped carboxyl organic linkers to make extended porous frameworks, with the aim of studying their performance as water adsorbents. Thus, we have evaluated the water adsorption properties of these new MOFs and other reported porous materials to identify the compounds with the most promising materials for use in applications such as thermal batteries or delivery of drinking water in remote areas. An X-ray single-crystal and a powder neutron diffraction study reveal the position of the water adsorption sites in one of the best performing materials, and highlight the importance of the intermolecular interactions between adsorbed water molecules within the pores.

Specific adsorption of sulfamate ions at the mercury/solution interface

1982 ◽  
Vol 60 (13) ◽  
pp. 1643-1647 ◽  
Author(s):  
Ernesto R. Gonzalez
Keyword(s):  
Ionic Strength ◽  
Activity Coefficient ◽  
Double Layer ◽  
Adsorbed Water ◽  
Water Molecules ◽  
Electrostatic Model ◽  
Solution Composition ◽  
Solution Interface ◽  
Double Layer Capacity ◽  
Mercury Electrodes

The adsorption of sulfamate ions on mercury electrodes has been studied by measuring the double layer capacity in constant ionic strength solutions of composition xM NH4SO3NH2 + (1−x)M NH4F. It was found that sulfamate ions are weakly adsorbed on mercury, the amount adsorbed being significant only for x > 0.1 at positive charges on the electrode. Because of this, the properties of the inner layer were found to be strongly dependent on the adsorbed water molecules and the structure of the diffuse layer. It was determined that the adsorption of sulfamate ions can be described by an isotherm based on the electrostatic model of the double layer. The possible effects of the activity coefficient variation with solution composition are discussed.

scholarly journals Effect of Water Adsorption on Cation-Surface Interaction Energy in the Na-Mordenite of 5.5 : 1 Si/Al Ratio

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Sekou Diaby
Keyword(s):  
Activation Energy ◽  
Surface Properties ◽  
Surface Potential ◽  
Water Adsorption ◽  
Adsorbed Water ◽  
Material Surface ◽  
Water Molecules ◽  
Zeolite Surface ◽  
Inner Surface ◽  
Insight Into

The mobility of the Na+cations localized at the inner surface of the studied mordenite zeolite depends on the material surface properties. In this work, we show that the activation energy,ΔEhop, relating to the Na+cation hopping displacement is associated to the surface potential and therefore can be used to get a better insight into the zeolite surface properties. Indeed, when molecules as water are adsorbed at the surface, they modify the surface potential energy and hence influence the value ofΔEhop. If the adsorbed molecules are polar they directly interact with the cations which become more mobile. The more theΔEhopvalue is, the less the amount of adsorbed water molecules is. Alterations of theΔEhopvalue with respect to the amount of adsorbed water molecules are interpreted using the Dubinin model which is based on simple adsorption principle.

scholarly journals Water Structure in Proteins in Solid State Studied by Near Infrared Spectroscopy

2017 ◽  
Vol 735 ◽  
pp. 168-172
Author(s):  
Siraporn Soonthonhut ◽  
Alfred A. Christy
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Water Adsorption ◽  
Near Infrared ◽  
Free Water ◽  
Adsorbed Water ◽  
Water Molecules ◽  
Combination Frequency ◽  
Adsorption Of Water ◽  
Combination Frequencies

Water adsorption in proteins is the crucial process of protein folding and structure stabilizing. Adsorption of water on proteins can be evaluated by near-infrared spectroscopy, a useful technique for observing combination frequency of a water molecule. In this work, albumin, lysozyme, and silk, were used as models for α-helix and β-pleated sheet proteins. Their NIR spectra during water adsorption process were measured by using an NIR spectrometer equipped with a transflectance accessory. Moreover, the quantitative adsorption of water was determined by gravimetric technique. The results indicate that, there are five different NIR absorptions arise from the OH combination frequencies of water adsorbed by albumin in the 5300-5100 cm-1 region. But there are only four absorptions for lysozyme and silk. The OH combination frequencies arising from water molecules in albumin indicate that it acquires free water molecules (5280 cm-1) and adsorbed water molecules through carbonyl-water interactions (5248 and 5160 cm-1) and amino-water interactions (5200 and 5120 cm-1). Interestingly, there is no indication for the presence of free water molecules in lysozyme and silk. Furthermore, the gravimetric results indicate that the rate of water adsorbed follows the order RW.Alb<RW.Lys<RW.Sil and total mass of water adsorbed per gram solid follows the order WAlb<WLys=WSil.

Ionic Properties of Hydrous Oxide Gels

1992 ◽  
Vol 293 ◽  
Author(s):  
J. Livage
Keyword(s):  
Electrode Materials ◽  
Sol Gel ◽  
Adsorbed Water ◽  
Solid Particles ◽  
Strong Interactions ◽  
Water Molecules ◽  
Electrochromic Devices ◽  
Hydrous Oxides ◽  
Ordered Phases ◽  
Sol Gel Process

AbstractThe sol-gel process offers new opportunities for the synthesis of ionic materials, specially in the shape of thin films. Hydrous oxides are obtained which exhibit specific properties arising from strong interactions betwwen adsorbed water molecules and the oxide network. Sol-gel derived coatings are good candidates as electrode materials for lithium batteries or electrochromic devices. Their open structure allows easier diffusion of Li+ions in the liquid phase while electrons are delocalized through the oxide network. Moreover, water molecules favor the formation of ordered phases leading to the deposition of layers with preferred orientation. Electrochemical insertion can then be described as an intercalation process between solid particles.

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