Interaction Of H2O Research Articles

IR study of solid phases formed in the Mg(HCOO)2–Cu(HCOO)2–H2O system

The infrared (IR) spectra of Mg(HCOO)2·2H2O and Mg1−xCux(HCOO)2·2H2O mixed crystals (0<x≤0.5) have been recorded and the internal modes of the formate groups and the water molecules are reported. The number of the bands corresponding to the fundamental vibrations of the HCOO groups and the H2O molecules in the Mg(HCOO)2·2H2O spectrum reflects the existence of two crystallographically different formate groups and water molecules in coincidence with the structural data. The red-shift of the OD vibrations (matrix-isolated HDO molecules) at liquid nitrogen temperature as compared to ambient temperature (dv/dT>0) evidences for the formation of linear hydrogen bonds. The IR spectra of Mg1−xCux(HCOO)2·2H2O mixed crystals show that the regions of 3200–3400cm−1 (νOH), 2300–2500cm−1 (νOD of matrix-isolated HDO), 500–950cm−1 (water librations) are mostly sensitive to the coordination environment of the metal ions. So the analysis of the IR spectra reveals that the copper ions are localized predominatingly at Me(1) sites in the mixed crystals, i.e. at sites with a six-fold coordination through six oxygen atoms from the formate groups only. Mg0.26Cu0.74(HCOO)2·2H2O (new crystal phase) forms monoclinic crystals with lattice parameters: a=12.347(4); b=7.240(4); c=8.736(6)Åβ=103.08(5)°; SG P21/c. The internal modes of the formate groups and the water molecules in the new crystal phase are discussed by analogy to Mg(HCOO)2·2H2O and Cu(HCOO)2·2H2O, since the structutal data are not available. The analysis of the spectra in the region of the uncoupled OD vibrations shows that probably more than two water molecules are expected to exist in the structure. It is assumed that the water molecules bonded to the copper ions form stronger hydrogen bonds due to the stronger Cu–H2O interactions (synergetic effect) than those bonded to the magnesium ions. The librational modes of the water molecules in all the solid phases studied are also discussed.

H2O Interaction with Solid H3PW12O40: An IR Study

The interactions of H2O with solid H3PW12O40 have been studied by IR spectroscopy, and the results are compared with those obtained for H2O interacting with other acidic or superacidic solid systems (acidic zeolites and the perfluorosulfonic membrane H-Nafion). In fully dehydrated HPW a heterogeneous family of hydroxyls is evidenced which, by interaction with water, leads to the formation of neutral 1:1 H-bond adducts. At higher water pressures, the formation of symmetric diaquahydrogen ions, and of clusters of protonated water is also observed. The H2O···H+···OH2 symmetrical adducts are characterized by a very broad absorption in the 1400−700 cm-1 range, which, by comparison with theoretical studies on gas-phase clusters and with experimental results obtained on H5O2+ salts, is assigned to the νO···H+···O mode. On the contrary, the IR spectra of fully dehydrated HPW do not show any absorption in this range.

X-ray Diffraction Study of Water Confined in Mesoporous MCM-41 Materials over a Temperature Range of 223−298 K

X-ray scattering measurements on water confined in the cylindrical pores of MCM-41 with different pore sizes C10 (diameter = 21 A) and C14 (28 A) have been performed over a temperature range of 223−298 K. Both samples were sealed in glass capillaries at relative water vapor pressures p/p0 = 0.3 and 0.6 under monolayer and capillary-condensed adsorption conditions, respectively. The X-ray radial distribution functions showed the presence of a distorted tetrahedral-like hydrogen-bonded network of water in both pores, characterized by peaks at ∼2.8, ∼4.2, and ∼4.9 A, with non-hydrogen-bonded H2O−H2O interactions at ∼3.3 A and H2O−Si interactions at ∼3.8 A between water and the silica wall. With decreasing temperature, the number of the hydrogen-bonded H2O−H2O interactions at 2.8 A increases, accompanied by the shifts of the 2.8 and 4.9 A peaks to shorter distances and of the 4.2 A peak to larger distances, for the capillary-condensed samples, showing a tendency to form more tetrahedral-like hydrogen-bonded w...

Calculation of the cadmium–water interface

This paper presents the results of a very nearly ab initio calculation of the molecular and electronic distributions at the interface of hcp cadmium and liquid water. The calculated results were obtained by combining a molecular dynamics simulation for the H2O molecular distributions with a self-consistent density functional calculation for the valence electron density of the cadmium surface. The method employs a three-dimensionally periodic unit cell, uses standard molecular dynamics potentials for H2O–H2O interactions, and calculates a self-consistent electronic structure for the metal at each time step of the molecular dynamics simulation, with the electron–H2O and electron–Cd interactions represented by pseudopotentials. The electronic and H2O distributions of the Cd–water interface are obtained both for zero applied potential, and for a range of electric potentials applied across the interface. Results are given for the equilibrium structure of interface, and its response to applied potentials. An analysis of the electrostatics of the interface yields a prediction for the compact capacitance of the cadmium–electrolyte interface, which is compared to experiment.

Experimental and Numerical Investigation of Adsorption/Desorption in Packed Sorption Beds under Ideal and Nonideal Flows

The importance of the wall effect on packed beds in the adsorption and desorption of carbon dioxide, nitrogen, and water on molecular sieve 5A of 0.127 cm radius is examined experimentally and with one-dimensional computer simulations. Experimental results are presented for a 22.5-cm long by 4.5-cm diameter cylindrical column with concentration measurements taken at various radial locations. The set of partial differential equations is solved using finite differences and Newmanss method. Comparison of test data with the axial-dispersed, nonisothermal, linear driving force model suggests that a two-dimensional model (submitted to Separation Science and Technology) is required for accurate simulation of the average column breakthrough concentration. Additional comparisons of test data with the model provided information on the interactive effects of carrier gas coadsorption with CO2 as well as CO2─H2O interactions.

Reactivity of NO2 and H2O on soot generated in the laboratory: a diffusion tube study at ambient temperature

In this work we have obtained the kinetic parameters and the product spectrum of NO2 and H2O separately interacting with soot samples in terms of surface residence times τs of the interacting molecules and uptake rate constant expressed as uptake coefficients (γ). The NO2 interaction on soot from either a decane or a toluene flame results in HONO as the main product in contrast to acetylene soot. NO was observed to be a minor product for all soot substrates investigated. Residence times up to 70 ms for NO2 interacting with acetylene soot and up to 50 ms with decane and toluene soot were obtained as well as initial uptake coefficients γ0MC ranging from 0.26 for NO2 on acetylene soot to an average value of 0.1 for NO2 on decane and toluene soot. All experiments were subject to significant saturation at typical doses of 1015 molecules. A Monte-Carlo (MC) trajectory model was applied to extract τs and γ0MC values, as well as the average number of adsorption sites ns. The interaction of NO2 with toluene and decane soot was modeled using a simple MC-model using a single adsorption site, whereas acetylene soot required a two-site model. For the interaction of H2O on soot, a residence time τs ranging from 0.1 ms on decane soot to 5 ms for acetylene soot has been determined using the single-reaction-site MC-model with τs values between 2 and 3 ms for toluene and diesel soot, respectively. For H2O an upper limit for the uptake coefficient γ0MC of 2 × 10−3 has been measured for all soot samples.

Anisotropic intermolecular interactions in van der Waals and hydrogen-bonded complexes: What can we get from density functional calculations?

The applicability of various density functional theory (DFT) methods to describe the anisotropy of the intermolecular potential energy surfaces of hydrogen-bonded [OH−–H2O, (H2O)2] and van der Waals [CO–H2O, He–CO2] complexes has been tested by comparison with supermolecule CCSD(T) (coupled-cluster method restricted to single, double, and noniterative triple excitations) and perturbational SAPT (symmetry-adapted perturbation theory) results computed for the same geometries and with the same basis sets. It is shown that for strongly bound ionic hydrogen-bonded complexes, like OH−–H2O, hybrid approaches provide accurate results. For other systems, including the water dimer, the DFT calculations fail to reproduce the correct angular dependence of the potential surfaces. It is also shown that a hybrid functional adjusted to reproduce the CCSD(T) value of the binding energy for the water dimer produces results worse than the standard hybrid functionals for OH−–H2O, and fails to describe the correct anisotropy of the CO–H2O interaction.

Simulations of liquid water in contact with a Cu(100) surface

An analytical potential for the description of the Cu(100)– H2O interaction derived from quantum calculations is proposed. As a test of its quality, a simulation of liquid water between two parallel copper electrodes was performed using Monte Carlo method. Several properties as obtained with this new potential, such as the oxygen and hydrogen density profiles, charge distribution profile, and the surface potential of water in contact with the hydrophobic metal surface, are presented. The perturbation caused in the structure of liquid water by the formation of the water–copper interface was found to be of a relatively short range. The relatively minor importance of the water–metal specific interaction and the decisive role of hydrogen bonding on the structure of water near the electrode are confirmed.

Diffraction Studies on Concentrated Aqueous Hydrochloric Acid Solutions

AbstractX‐ray diffraction and neutron diffraction experiments with H/D isotopically substituted aqueous 21 mol% hydrochloric acid solutions were carried out in order to obtain detailed features concerning the intermolecular hydrogen‐bonded structure in highly concentrated aqueous acidic solutions. Structure parameters, namely, intermolecular distance, root‐mean‐square amplitude, and coordination number, for the nearest neighbor H3O+···H2O interaction were determined from the least‐squares‐fitting analysis of the observed X‐ray interference term. These were, respectively, r(H3O+···H2O) = 2.45(1) Å; l(H3O+···H2O) = 0.11(1) Å; and n(H3O+···H2O) = 1.8(1). The intermolecular nearest neighbor distances, r(H···H) = 2.02(5) Å and r(O···H) = 1.69(2) Å, were determined from the least‐squares fit to partial structure factors, aij (Q), derived from the observed neutron intermolecular interference terms for sample solutions with different H/D isotopic ratios. The present values of intermolecular distances are significantly shorter than those for pure liquid water, implying that extremely strong hydrogen bonds exist in concentrated aqueous acidic solutions.

Simulations of H2O Solid, Liquid, and Clusters, with an Emphasis on Ferroelectric Ordering Transition in Hexagonal Ice

Simulations are presented of H2O ice, liquid, and clusters (H2O)n n ≤ 7. The first part is devoted to orientational energetics of ice. Ordinary hexagonal ice is orientationally disordered; a transition to an ordered form (ice XI) can be induced at 72 K. The recently demonstrated ferroelectric structure of ice XI (Jackson, S. M.; Wield, V. M.; Whitworth, R. W.; Oguro, M.; Wilson, C. J. Phys. Chem. B 1997, 101, 6142) seems to contradict our understanding of H2O···H2O interactions. A polarizable water potential is proposed that accounts qualitatively for the existence of ferroelectric ice XI; its crucial ingredient is the location of the polarizability center. This potential is then tested in classical trajectory simulations of water structure, energetics, self-diffusion, and dielectric constant. Cluster energetics and rotational constants are calculated using the rigid body diffusion Monte Carlo technique.

A molecular dynamics study of the Cr3+ hydration based on a fully flexible hydrated ion model

A theoretical study of the Cr3+ hydration in aqueous solutions has been carried out by means of molecular dynamics (MD) simulations. Ion–water intermolecular interaction potentials are based on first principles using the idea of the previously developed hydrated ion–water interaction potential: The bare ion, Mn+, is replaced by its corresponding hydrate, [M(H2O)6]n+, and the water molecules interact with the hydrate by means of an ab initio [M(H2O)6]n+–H2O interaction potential. A new ab initio interaction potential has been developed to describe the Mn+–(H2O)first-shell interaction based on an examination of the hexahydrate potential-energy surface section that distorts the position of one of the cluster water molecules, the remaining five fixed at their equilibrium position. These two complementary interaction potentials, which describe ion–water interactions have been combined with the TIP4P model for water molecules. Structural and dynamical results derived from the analysis of 1 ns of simulation for a sample formed by [Cr(H2O)6]3+ and 512 H2O are presented. Rigidity effects of the cluster are examined by comparing the present results with those previously obtained with a model of rigid hexahydrate [J. Phys. Chem. B 102, 3272 (1998)]. A new definition of hydrated ion based on the rotational properties of its hydrate is supported.

Thermodynamic Model of the System H+−NH4+−Na+−SO42-−NO3-−Cl-−H2O at 298.15 K

A multicomponent mole-fraction-based thermodynamic model of the H+−NH4+−Na+−SO42-−NO3-−Cl-−H2O system is used to represent aqueous-phase activities, equilibrium partial pressures (of H2O, HNO3, HCl, and NH3), and saturation with respect to 19 solid phases ((NH4)2SO4(cr), (NH4)3H(SO4)2(cr), NH4HSO4(cr), NH4NO3(cr), NH4Cl(cr), Na2SO4·10H2O(cr), Na2SO4(cr), Na3H(SO4)2(cr), NaHSO4·H2O(cr), NaHSO4(cr), NaH3(SO4)2·H2O(cr), NaNO3(cr), NaCl(cr), NH4HSO4·NH4NO3(cr), (NH4)2SO4·2NH4NO3(cr), (NH4)2SO4·3NH4NO3(cr), (NH4)2SO4·Na2SO4·4H2O(cr), Na2SO4·NaNO3·H2O(cr), 2NaNO3·NH4NO3(cr)). The model is valid for concentrations from infinite dilution to saturation (with respect to the solid phases) and to about 40 mol kg-1 for acid sulfate systems which can remain liquid to concentrations approaching the pure acid. Parameters for H2SO4−H2O interactions were adopted from a previous study, and values for other binary (water−electrolyte) and ternary (water and three ions) interactions were determined from extensive literature da...

Thermodynamic Model of the System H+−NH4+−SO42-−NO3-−H2O at Tropospheric Temperatures

A multicomponent mole-fraction-based thermodynamic model is used to represent aqueous phase activities, equilibrium partial pressures (of H2O, HNO3, and NH3), and saturation with respect to solid phases (H2SO4 and HNO3 hydrates, (NH4)2SO4(cr), (NH4)3H(SO4)2(cr), NH4HSO4(cr), (NH4)2SO4·2NH4NO3(cr), (NH4)2SO4·3NH4NO3(cr), and NH4HSO4·NH4NO3(cr)) in the system H+−NH4+−SO42-−NO3-−H2O. The model is valid from 328 to <200 K, dependent upon liquid-phase composition. Parameters for H2SO4−H2O, HNO3−H2O, and (NH4)2SO4−H2O interactions were adopted from previous studies, and values for NH4NO3−H2O obtained from vapor pressures (including data for supersaturated solutions), enthalpies, and heat capacities. Parameters for ternary interactions were determined from extensive literature data for salt solubilities, electromotive forces (emfs), and vapor pressures with an emphasis upon measurements of supersaturated H2SO4−(NH4)2SO4−H2O solutions. Comparisons suggest that the model satisfactorily represents partial pressures...

Monte Carlo simulations and neutron diffraction studies of the peptide forming system 0.5 mol kg-1CuCl2–5mol kg-1NaCl[ndash ]H2Oat 293 and 353 K

Monte Carlo simulations at temperatures of 293 and 353 K have been performed for a 0.5 mol kg−1 CuCl2–5 mol kg−1 NaCl aqueous solution, which has been found to induce condensation of amino acids to peptides. Because pair potentials are insufficient to describe CuII solvation phenomena correctly, three-body terms were incorporated, based on abinitio derived potentials for Cu2+–H2O–H2O and Cu2+–Cl−–H2O interactions. The structure of the solvated ions is discussed in terms of radial density functions and coordination number, angular and energy distributions. A neutron diffraction study was also carried out on a solution of the same concentration at 298 K. The method of isotopic substitution was applied to the copper(II) ions (63Cu and 65Cu) and to the water molecules (H2O and D2O) and results obtained for the Cu2+ coordination and the water structure. Comparison of the former with those of the simulation shows that there is broad agreement for the CuII coordination; both techniques show evidence of direct contact between Cu2+ and Cl− and indicate [Cu(H2O)5Cl1]+ to be the prevalent copper species in solution. In addition, the neutron diffraction and isotopic substitution (NDIS) results show that the H-bond structure is strongly perturbed by the presence of a high concentration of ions.

98/00252 Deep coal-bed methane in Alberta, Canada: a fuel resource with the potential of zero greenhouse gas emissions

Aluminum (Al), the most abundant metallic element on the earth crust, has been reckoned as a promising battery material for its the highest theoretical volume capacity (8046 mAh cm−3). Being rechargeable in ionic liquid electrolytes, however, the Al anode and battery case suffer from corrosion. On the other hand, Al is irreversible in aqueous electrolyte with severe hydrogen evolution reaction. Here, we demonstrate a water-in-salt aluminum ion electrolyte (WISE) based on Al and lithium salts to tackle the above challenges. In the WISE system, water molecules can be confined within the Li + solvation structures. This diminished Al3+-H2O interaction essentially eliminates the hydrolysis effect, effectively protecting Al anode from corrosion. Therefore, long-term Al plating/stripping can be realized. Furthermore, two types of high-performance full batteries have been demonstrated using copper hexacyanoferrate (CuHCF, a Prussian Blue Analogues) and LiNi0·8Co0·1Mn0·1O2 (NCM) as cathodes. The reversibility of Al anode laid the foundation for low cost rechargeable batteries suffering for large-scale energy storage.Broader context: Al batteries are expected to become a safe and sustainable alternative to lithium batteries. For decades, chase for a feasible Al secondary battery has not been successful. The key challenge is to find suitable cathode and electrolyte materials, together with which Al anode battery can function reversibly. Currently, fatal drawbacks have impeded the practical application of Al metal batteries (AMBs), such as sustained corrosion of Al anode and battery case in ionic liquid electrolytes, irreversibility issues as well as severe hydrogen evolution reaction during cycling in aqueous electrolyte. Therefore, electrolyte and their electrochemical kinetics play a vital role in the performance and environmental operating limitations of high-energy Al metal batteries. In this work, we demonstrate a nearly neutral Al ion water-in-salt electrolyte (WISE) to tackle the above challenges. The WISE shows excellent stability in the open atmosphere. The distinct solvation-sheath structure of Al3+ in the WISE system would protect Al metal anodes from corrosion and eliminate hydrogen evolution reaction effectively, further promoting the reversibility of Al metal anodes with dendrite-free morphology. Moreover, such a WISE exhibits superior compatibility with LiNi0·3Co0·3Mn0·3O2 (NCM) and copper hexacyanoferrate (CuHCF) cathodes and long-term stabilities with high coulombic efficiency (CE) can be attained for full batteries with the WISE. The approach in this study can furnish an opportunity to develop reversible AMBs and lay the foundation for other potential multivalent-metal-based secondary batteries suffering from interface passivation and poor reversibility, which suggest the promise of multivalent metal batteries and their applications in large-scale energy storage.

The ab initio neon–water potential-energy surface and its relationship with the hydrophobic hydration shell

The neon–water system has been investigated by abinitio quantum-chemical calculations. The potential-energy surface (PES) for the 1:1 Ne–H2O interaction has been scanned at the MP2(full) level, with the 6-311++G(3df,2pd) basis set augmented with bond functions located midway between Ne and O. The most stable neon–water arrangement has r = 320 pm, θ = 120°, with a counterpoise-corrected binding energy of −0.54 kJ mol−1. The PES is otherwise quite flat (with binding energies of ca. −0.4 kJ mol−1) for all θ values if r > ca. 310 pm. The off-plane, perpendicular approach is unfavourable. NMR shielding and the electric field gradient at all nuclei show only very small changes with respect to the isolated components.

The interaction of H2O with an electron paramagnetic resonance center in oxidized, heat treated SiC

We examine a defect in heat treated, oxidized 6H-SiC with electron paramagnetic resonance spectroscopy. Samples are examined before treatment, after oxidation, after dry (&amp;lt;10 ppm H2O) N2 heat treatment, and after standard (approximately 50 ppm H2O) Ar annealing. A center is observed following dry heat treatment at temperatures greater than 800 °C. This center is passivated by standard Ar annealing at temperatures greater than 700 °C and regenerated after subsequent dry heat treatment. We suggest that this defect is related to an unpaired electron on a carbon atom created by the release of a hydrogen-related species.

The role of the rotational state in intermolecular interactions of H2O with H2 and CH3Cl

Rotational-state resolved measurements of H2O−H2 and H2O−CH3Cl intermolecular interactions were performed. Using light-induced drift as a tool, we measured changes in transport collision ratev upon rovibrational (J, r)-excitation of H2O. We studied P- and R-branch excitation withJ ranging from O through 9 for H2O excited in the fundamental asymmetric stretch mode. Combination of P and R data yields the dependencies ofv upon rotational (J) and vibrational (r) quantum numbers separately. For H2O−CH3Cl it is found thatv decreases by 25% asJ increases from 0 to 9. For H2O−H2 the decrease is only 1.0%. These data seem to exemplify a fundamental aspect of dipole-dipole interaction: the familiar 1r3 interaction term is highlyJ-dependent. This is attributed to the increasing averaging-out of the dipolar potential as the rotational quantum number increases.

鉄酸化物の生成と構造

The formation mechanism of ferric oxide hydroxides, α-, β- and γ-FeOOH, is described in view of evolution of colloidal particles in aqueous solutions. The surface characterization of FeOOH particles by IR spectroscopy is cited. Finally, the adsorption interaction of H2O, SO2 and NO with the particles is explained based on their surface structures.

Examining the influence of the [Zn(H2O)6]2+ geometry change on the Monte Carlo simulations of Zn2+ in water

Quantum chemical calculations have been carried out to estimate the variation in the interaction energy between one or two water molecules and the Zn2+ hydrated ion ([Zn(H2O)6]2+) when the Zn–O intramolecular distance is changed. Likewise, changes in the interaction energy between a second hydration shell formed by twelve H2O and the hydrated ion when shrinking the hexahydrate have been also examined, using a previously reported hydrated ion–water potential [Pappalardo et al., J. Phys. Chem. 97, 4500 (1993)] and the Matsuoka–Clementi–Yoshimine (MCY) potential for the water–water interactions. Using these potentials and that of Clementi for the Zn2+–H2O interaction, Monte Carlo simulations have been performed using two different Zn–O distances for the first hydration shell. Results show that influence of the geometrical relaxation on the solvation energy is not large, about 2.5%. Consequences on the use of a flexible or rigid hydrated ion are discussed.