Binding Energies Of Ions Research Articles

Organic Tetrabutylammonium Cation Intercalation to Heal Inorganic CsPbI3 Perovskite.

The in situ formation of reduced dimensional perovskite layer via post-synthesis ion exchange has been an effective way of passivating organic-inorganic hybrid perovskites. In contrast, cesium ions in Cs-based inorganic perovskite with strong ionic binding energy cannot exchange with those well-known organic cations to form reduced dimensional perovskite. Herein, we demonstrate that tetrabutylammonium (TBA+ ) cation can intercalate into CsPbI3 to effectively substitute the Cs cation and to form one-dimensional (1D) TBAPbI3 layer in the post-synthesis TBAI treatment. Such TBA cation intercalation leads to in situ formation of TBAPbI3 protective layer to heal defects at the surface of inorganic CsPbI3 perovskite. The TBAPbI3 -CsPbI3 perovskite exhibited enhanced stability and lower defect density, and the corresponding perovskite solar cell devices achieved an improved efficiency up to 18.32 % compared to 15.85 % of the control one.

Organic Tetrabutylammonium Cation Intercalation to Heal Inorganic CsPbI3 Perovskite

AbstractThe in situ formation of reduced dimensional perovskite layer via post‐synthesis ion exchange has been an effective way of passivating organic‐inorganic hybrid perovskites. In contrast, cesium ions in Cs‐based inorganic perovskite with strong ionic binding energy cannot exchange with those well‐known organic cations to form reduced dimensional perovskite. Herein, we demonstrate that tetrabutylammonium (TBA+) cation can intercalate into CsPbI3 to effectively substitute the Cs cation and to form one‐dimensional (1D) TBAPbI3 layer in the post‐synthesis TBAI treatment. Such TBA cation intercalation leads to in situ formation of TBAPbI3 protective layer to heal defects at the surface of inorganic CsPbI3 perovskite. The TBAPbI3‐CsPbI3 perovskite exhibited enhanced stability and lower defect density, and the corresponding perovskite solar cell devices achieved an improved efficiency up to 18.32 % compared to 15.85 % of the control one.

Metal doped graphene oxide derived from Quercus ilex fruits for selective and visual detection of iron(III) in water: Experiment and theory

Iron is one of the most abundant metals and an important micronutrient that needs to be consumed in balanced amounts. Excess consumption or deficiency of this micronutrient can have adverse effects on biological functioning of human organs. Hence, the selective detection of this micronutrient is very important. The present work reports a simple and selective sensing of iron (III) in aqueous solutions using potassium doped graphene oxide (K-doped GO), which is synthesized from Quercus ilex fruits via a greener route of solvo-hydrothermal method. The synthesis of K-doped GO is confirmed with the help of various characterisation techniques viz. X-Ray Diffraction (XRD), Raman Spectroscopy, Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Analysis (EDX), and Fourier Transform Infrared Spectroscopy (FT-IR).The Density Functional Theory (DFT) based first principle simulations are carried out to understand the interactions between K-doped GO and iron ions. The simulations reveal desorption of K-ions from the GO sheet due to the extremely high binding energy of iron ions on GO surface, which destabilizes the oxide groups as well as the potassium dopant. The desorbed K-ions from GO surface may react with water to form potassium hydroxide and subsequent quenching of fluorescence. Thus, the synthesized K-doped GO demonstrates its utility as a heavy metal ion sensor with detection limit of 0.345*10−7 M iron ions via spectrofluorometer. Moreover, this material is capable of detecting the presence of iron ions in water up to a limit of 7 ppm with naked eye.

Effect of Ce modification on desulfurization performance of regenerated sorbent for high temperature H2S removal from coal gas

Ce modified MnxOy/Al2O3-La have been prepared to investigate the effect of Ce loadings on pre-breakthrough H2S removal efficiency, breakthrough sulfur capacity (BSC) and BSC durability of the sorbents during desulfurization-regeneration cycles. The results showed Ce modification could improve the pre-breakthrough H2S removal efficiency of regenerated sorbents during desulfurization-regeneration cycles. The XPS characterization showed that the Ce can promote the binding energy of Mn ion to shift to lower energy, which enhanced H2S adsorption on the regenerated sorbent. However, the Ce loading sequence had effect on BSC durability of sorbent during desulfurization-regeneration cycles. The Ce-MnxOy/Al2O3-La with co-impregnation of Mn and Ce oxides had higher BSC than MnxOy/Al2O3-La, while the Ce/MnxOy/Al2O3-La with Ce loading on the surface of MnxOy/Al2O3-La had lower BSC and worse BSC durability than MnxOy/Al2O3-La. The characterization results showed Ce-MnxOy/Al2O3-La obtained better surface area and pore structure than MnxOy/Al2O3-La, and Ce ion can promote the increasing of the around electron density of Mn ion, which was beneficial for H2S adsorption of Ce-MnxOy/Al2O3-La. The poor surface area and pore structure would cause the low BSC of Ce/MnxOy/Al2O3-La, and less stability of pore structure might lead to poorer BSC durability of Ce/MnxOy/Al2O3-La than MnxOy/Al2O3-La during desulfurization-regeneration cycles.

Structural modelling of the lumenal domain of human GPAA1, the metallo-peptide synthetase subunit of the transamidase complex, reveals zinc-binding mode and two flaps surrounding the active site

BackgroundThe transamidase complex is a molecular machine in the endoplasmic reticulum of eukaryotes that attaches a glycosylphosphatidylinositol (GPI) lipid anchor to substrate proteins after cleaving a C-terminal propeptide with a defined sequence signal. Its five subunits are very hydrophobic; thus, solubility, heterologous expression and complex reconstruction are difficult. Therefore, theoretical approaches are currently the main source of insight into details of 3D structure and of the catalytic process.ResultsIn this work, we generated model 3D structures of the lumenal domain of human GPAA1, the M28-type metallo-peptide-synthetase subunit of the transamidase, including zinc ion and model substrate positions. In comparative molecular dynamics (MD) simulations of M28-type structures and our GPAA1 models, we estimated the metal ion binding energies with evolutionary conserved amino acid residues in the catalytic cleft. We find that canonical zinc binding sites 2 and 3 are strongest binders for Zn1 and, where a second zinc is available, sites 2 and 4 for Zn2. Zinc interaction of site 5 with Zn1 enhances upon substrate binding in structures with only one zinc. Whereas a previously studied glutaminyl cyclase structure, the best known homologue to GPAA1, binds only one zinc ion at the catalytic site, GPAA1 can sterically accommodate two. The M28-type metallopeptidases segregate into two independent branches with regard to one/two zinc ion binding modality in a phylogenetic tree where the GPAA1 family is closer to the joint origin of both groups. For GPAA1 models, MD studies revealed two large loops (flaps) surrounding the active site being involved in an anti-correlated, breathing-like dynamics.ConclusionsIn the light of combined sequence-analytic and phylogenetic arguments as well as 3D structural modelling results, GPAA1 is most likely a single zinc ion metallopeptidase. Two large flaps environ the catalytic site restricting access to large substrates.ReviewersThis article was reviewed by Thomas Dandekar (MD) and Michael Gromiha.

High proton conductivity at low and moderate temperature in a simple family of Prussian blue analogs, divalent transition metal hexacyanocobaltates (III)

Proton conductivity behavior was studied in a family of hexacyanocobaltates with divalent transition metals (II), HCCMs. The HCCMs, with molecular formula M3[Co(CN)6]2∙xH2O (where M = Ni, Co, Fe, Mn and Cd), had cubic crystal structures and similar cell parameters. The number of water molecules per formula unit (x) present in each HCCMs was determined from thermogravimetric analysis data. Differences in conductivity values were evaluated by running dielectric impedance experiments. The values of the permittivity and conductivity real and imaginary parts were obtained for each material. The actual conductivity part was analyzed as a temperature and frequency function. Mobilities, diffusivities, and ion charge densities were derived from the electrode polarization model that appropriately fits the loss tangent curves. The measurement conditions for all the samples were relative humidity of 99% and temperature ranging from 25 to 105 °C. The conductivity values obtained for the HCCMs varied from 10−4 to 10−2 S cm−1. At low temperatures, proton conductivity values for the nickel hexacyanocobaltate (HCCNi) stood out (from 10 -3 and 10−2 S cm−1, at 25 and 45 °C, respectively), followed by Fe, Cd, Co and Mn. In addition to the results stated above, activation energies were determined using the Arrhenius model, where the obtained values were below 21.1 kJ mol−1. The proton transport activation energies suggest that the transport through the HCCM porous framework was achieved by the Grotthuss mechanism. The diffusivity in the porous framework increased with temperature for all the samples except for HCCNi, following the trend DHCCFe > DHCCMn> DHCCCo> DHCCCd. The variability observed between the samples could be related to the ion-binding energies (Eb). These results indicate that hexacyanocobaltates can be useful as mixed matrix membrane (MMM) fillers, providing excellent conductivity and diffusivity when the medium contains a sufficient amount of ionic components depending on the involved transition metal.

Influence of the anion on diffusivity and mobility of ionic liquids composite polybenzimidazol membranes

The study of proton conductivity processes has received increasing attention in the past decades due to their potential applications in fields such as electrochemical devices and fuel cells. Despite the high number of composite membranes which have been described for this purpose, fundamental studies of the conduction phenomena in polymeric membranes are scarce. In this article, we study on the effect of the anion on ionic conductivity of ionic liquid composite polybenzimidazole (PBI) membranes. These membranes, which contain 1-butyl-3-methylimidazolium (BMIM) with different counterions ([Cl]–, [NCS]–, [NTf2]– and [BF4]–) were analyzed by electrochemical impedance spectroscopy (EIS) in order to study the influence of the anion on the ionic conductivity, but also mobility and charge carrier density at different temperatures. The methodology for this analysis is based on the Coelho model of electrode polarization (EP), where the dependence of the complex dielectric permittivity on frequency is represented in terms of a Cole-Cole function, contrarily to the generally used simple Debye relaxation. The calculated activation energies associated to the conductivity showed a dependence on the anion and is around 65–84 kJ mol−1, which suggests that the ionic conductivity mainly occurs through the vehicle-type mechanism. The calculated diffusivity values followed the trend D NTf2 > D Cl > D BF4> D SCN, with an associated activation energy (in kJ·mol−1) following the trend Eact(NTf2) = 10.9 < Eact(Cl) = 12.6 < Eact(BF4) = 18.5 < Eact(SCN) = 25.1. The comparison between these values reveals that a decrease in the ion binding energies (Eb) and stabilization energies (Es) could be responsible for the growth of the diffusion coefficient around one or two orders of magnitude depending on temperature and anion. The low stabilization energy observed for the NTF2- and Cl− anions in comparison with NCS− and BF4, can be attributed to the poor stabilization of separated ion pairs by coordination with the PBI segments, which is reflected in the values of the dielectric permittivity (εs) calculated by EIS.

Capability of CI-Orbitrap for Gas-Phase Analysis in Atmospheric Chemistry: A Comparison with the CI-APi-TOF Technique.

Chemical ionization Orbitrap mass spectrometry (CI-Orbitrap) represents a promising new technique for gas-phase analysis in analytical and atmospheric chemistry mainly due to its very high mass resolving power. In this work, we performed the first side-by-side comparison between a CI-Orbitrap and the widely used atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-TOF) using two different chemical ionization methods, i.e., acetate-ion-based (CH3COO-) and aminium-ion-based (n-C3H7NH3+) schemes. The capability of the CI-Orbitrap at accurately measuring low concentrations of gaseous species formed from the oxidation of α-pinene was explored. Although this study reveals a lack of linearity of the CI-Orbitrap when measuring product ions at very low concentrations (<1 × 106 molecules cm-3), very good agreement between both techniques can be achieved by applying a newly developed linearity correction. It is experimentally shown that the correction function is independent of the reagent ion used. Thus, accurate quantification of organic compounds at concentrations as low as 1 × 105 molecules cm-3 by the CI-Orbitrap can be achieved. Finally, by means of tandem mass spectrometry, the unique capability of the Orbitrap allows the direct determination of the binding energy of cluster ions between analyte and reagent ions, that is needed for the assessment of a chosen ionization scheme.

QED theory of the normal mass shift in few-electron atoms

The electron-electron interaction correction of first order in $1/Z$ to the one-electron part of the nuclear recoil effect on binding energies in atoms and ions is considered within the framework of the rigorous QED approach. The calculations to all orders in $\alpha Z$ are performed for the $1s^2$ state in heliumlike ions and the $1s^2 2s$ and $1s^2 2p_{1/2}$ states in lithiumlike ions in the range $Z=5$--$100$. The results obtained are compared with the Breit-approximation values. The performed calculations complete a systematic treatment of the QED nuclear recoil effect up to the first order in $1/Z$. The correction obtained is combined with the previously studied two-electron part as well as the higher-order electron-correlation corrections evaluated within the Breit approximation to get the total theoretical predictions for the mass shifts.

Low-Energy Electron Elastic Total Cross Sections for Ho, Er, Tm, Yb, Lu, and Hf Atoms

The robust Regge-pole methodology wherein is fully embedded the essential electron-electron correlation effects and the vital core polarization interaction has been used to explore negative ion formation in the large lanthanide Ho, Er, Tm, Yb, Lu, and Hf atoms through the electron elastic total cross sections (TCSs) calculations. These TCSs are characterized generally by dramatically sharp resonances manifesting ground, metastable, and excited negative ion formation during the collisions, Ramsauer-Townsend minima, and shape resonances. The novelty and generality of the Regge-pole approach is in the extraction of the negative ion binding energies (BEs) of complex heavy systems from the calculated electron TCSs. The extracted anionic BEs from the ground state TCSs for Ho, Er, Tm, Yb, Lu, and Hf atoms are 3.51 eV, 3.53 eV, 3.36 eV, 3.49 eV, 4.09 eV and 1.68 eV, respectively. The TCSs are presented and the extracted from the ground; metastable and excited anionic states BEs are compared with the available measured and/or calculated electron affinities. We conclude with a remark on the existing inconsistencies in the meaning of the electron affinity among the various measurements and/or calculations in the investigated atoms and make a recommendation to resolve the ambiguity.

Vibrational Quenching of Weakly Bound Cold Molecular Ions Immersed in Their Parent Gas

Hybrid ion–atom systems provide an excellent platform for studies of state-resolved quantum chemistry at low temperatures, where quantum effects may be prevalent. Here we study theoretically the process of vibrational relaxation of an initially weakly bound molecular ion due to collisions with the background gas atoms. We show that this inelastic process is governed by the universal long-range part of the interaction potential, which allows for using simplified model potentials applicable to multiple atomic species. The product distribution after the collision can be estimated by making use of the distorted wave Born approximation. We find that the inelastic collisions lead predominantly to small changes in the binding energy of the molecular ion.

INVITED] Improved parameters for the lanthanide [formula omitted] and [formula omitted]5d curves in HRBE and VRBE schemes that takes the nephelauxetic effect into account

In first approximation the binding of an electron in lanthanide 4fq ground states changes with q in a characteristic zigzag shape that is independent on type of compound. Those shapes have been parameterized in past publications and are used to construct host referred binding energy (HRBE) or vacuum referred binding energy (VRBE) schemes showing the lanthanide 4fq level locations with respect to the host valence bands or to the vacuum level. There is experimental evidence for a slight compound dependence, and a model explaining that has appeared recently (Dorenbos, 2019). This all implies that the parameters for constructing HRBE and VRBE schemes need to be revised and a compound dependence needs to be introduced as a second order approximation. In this work the improved parameters are derived from the 3rd and 4th ionization potentials of the lanthanide atoms. In compounds, as explained by the chemical shift model, the free ion binding energy curves undergo an upward shift due to Coulomb repulsion from anion ligands and they undergo a tilt due to the lanthanide contraction. In this work we will use the nephelauxetic parameter β to add a compound dependence. Its main effect is an increased binding in the 4fq ground states for the lanthanides from the right hand branch (q > 7) of the zigzag curves. The same applies for the 4fq−15d excited states with (q−1)>7. Collected spectroscopic data on divalent and trivalent lanthanides from more than 1000 different compounds have been analyzed to arrive at the proposed revised parameters for the 4fq and 4fq−15d binding energy curves.

Adsorption mechanisms of Mo2CrC2 MXenes as potential anode materials for metal-ion batteries: A first-principles investigation

Two dimensional MXene are attracting increasing interests as electrode materials for metal ion batteries (MIBs) because metal ions can diffuse in a 2D lattice surface. In this work, first-principles calculations were carried out to investigate the adsorption performance of monolayer Mo2CrC2 for Li, Na, and K. The results show strong storage ability for various metal cations. There are three layers of Li, two layers of Na, one layer of K, and four layers of Mg on both sides of the monolayer. The electrochemical and thermodynamics of the intercalation of metal ions on the Mo2CrC2 Mxene have been intensively investigated. There is no band gap at the Fermi level of any configuration indicating that it has excellent electronic conductivity leading to an asymmetric electron localization distribution. The binding energy of metal ions decreases as the ion concentration increases. The adsorption of metal ions on a mono-layer of Mo2CrC2 has been studied, and the results indicate that the metal ions obviously improved the diffusion of metal ions. The CI-NEB method was used to study the diffusion of a cation on a Mo2CrC2 surface and search for its lowest energy along the diffusion pathway. Their structural transformations were studied via ab initio molecular dynamic (AIMD) simulations at a series of temperatures. The metal ions gradually evolved via thermal motion with increasing temperature. These results suggest that Mo2CrC2 could be a promising electrode material for Li- and Na-ion batteries in terms of Mo2CrC2 specific capacity, diffusion dynamics, and structural stability.

Disposal of the Lithium-ion Current Sources by Mechanochemical Degradation

Lithium-ion current sources in a ball mill and comparing this energy with the binding energies of lithium ions with various metals of a cathode material for mechanochemical destruction. The binding energies of lithium ions in various lithium-containing compounds are shown. The calculation of the technological and design parameters of the ball mill to determine the magnitude of the energy of the collision of the grinding bodies and the grinded material. The graphic dependences are given, allowing to reveal the influence of the ratio of the diameter of the balls and their number on the process of mechanochemical destruction.

QED theory of the specific mass shift in few-electron atoms

The quantum electrodynamics formalism to treat the interelectronic-interaction correction of first order in $1/Z$ to the two-electron part of the nuclear recoil effect on binding energies in atoms and ions is developed. The nonperturbative in $\alpha Z$ calculations of the corresponding contribution to the energies of the $1s^2$ state in He-like and the $1s^2 2s$ and $1s^2 2p_{1/2}$ states in Li-like ions are performed in the range $Z=5-100$. The behavior of the two-electron part of the nuclear recoil effect beyond the lowest-order relativistic approximation as $Z$ grows is studied.

Plasma corrosion resistance of aluminosilicate glasses containing Ca, Y and B under fluorocarbon plasma with Ar+

In this study, the corrosion resistance of alumino-silicate glass containing Ca, Y and B is assessed against CF4/O2/Ar plasma, with the results compared to those of poly-crystalline and single-crystalline alumina. All of the alumino-silicate glasses containing Ca, Y and B were more resistant than sintered alumina to a plasma-etching gas. Glass samples with boron oxide were less corroded by plasma than those without B2O3, and their surfaces were contaminated by the CFx generated by the plasma reaction.CaO-Y2O3-Al2O3-SiO2 (CYAS) showed a lower etch rate than sapphire and retained a smooth surface microstructure, unlike sintered alumina. The plasma resistance improved with an increase in the calcium oxide content. The improved plasma resistance of CYAS glass is thought to be due to the high sublimation temperature of the calcium fluoride and the strong atomic binding energy of the calcium ions in the glass.

Theoretical modeling of sorption of metal ions on amino-functionalized macroporous copolymer in aqueous solution.

With regard to the harmful effects of heavy metals on human health and the environment, the demand for synthesis and investigation of macromolecules with large capacity of harmful substances sorption is ever greater. Quantum-chemical methods may be applied in structural modeling, prediction, and characterization of such molecules and reactions. Sorption of metal ions (Cu2+, Cd2+, Co2+, and Ni2+) to triethylenetetramine-functionalized copolymer poly(GMA-co-EGDMA)-teta was successfully modeled by quantum chemical calculations, at the B3LYP//6-311++G**/lanl2dz level. Optimized structures of metal complexes were used for calculation of real binding energy of metal ion within the complex (ΔEr). Solvent and hydrolyzation effects were essential for obtaining the objective values. Solvent effect was included in ΔEr by using the total solvation energy for reaction of formation of tetaOH complex (ΔEs1, the first approach) or by using dehydration energy of free metal ion (ΔEs2, the second approach). Experimental results were confirmed in our theoretical analyses (using the second approach). Graphical abstract Theoretical modeling of divalent metal ions sorption on triethylenetetramine-functionalized copolymer poly(GMA-co-EGDMA)-teta.

Ligation Kinetics as a Probe for Non-Covalent Electrostatic Bonding and Electron Solvation of Alkali and Alkaline Earth Cations with Ammonia.

Mono-ligation kinetics were measured for ammonia reacting with atomic cations in the first two groups of the periodic table (K+, Rb+, Cs+ and Ca+, Sr+, Ba+). Also, mono-ligation energies were computed using density functional theory (DFT) in an attempt to assess the role of non-covalent electrostatic interactions in these chemical reactions. The measurements were performed at room temperature in helium bath gas at 0.35Torr using an inductively coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. Rate coefficients are reported for ammonia addition, the only reaction channel that was observed with all these cations. A systematic decrease in the rate of addition of NH3 was observed for both group 1 and 2 cations going down the periodic table. The computational studies predict a decrease in the adduct binding energy and an increase in the bond separation going down groups 1 and 2 of the periodic table and provide some insight into the role of the extra selectron in the group 2 radical cations in ligand bonding. A correlation is seen between the efficiency of ligation and the binding energy of the adduct ion and attributed to the lifetime of the intermediate encounter complex against back dissociation which is dependent on its well depth. Higher-order additions of ammonia were also observed. Remarkable differences in the extent and kinetics were seen between the group 1 and 2 cations, and these were attributed to the occurrence of ammonia solvation of the extra s electron in the higher-order adducts of the alkaline earth cations.

Fluorination effect in the volatility of imidazolium-based ionic liquids

The volatility and cohesive energy of fluorinated ionic liquids, FILs, was evaluated and used to explored and understand the effect of fluorination of the ILs cations and anions on the cohesive interaction and structuration. For this, the vapour pressures at different temperatures using a Knudsen effusion apparatus coupled with a quartz crystal microbalance were measured for three fluorinated imidazolium-based ionic liquids. The enthalpies and entropies of vaporization were derived from the temperature dependence of the vapour pressures. The degree of fluorination of the ions leads to an increase of the IL volatility following the order: [C8mim][NTf2] < [C8mim][BETI] < [C8H4F13mim][NTf2] < [C8H4F13mim][BETI]. The Gibbs energy of vaporization follows the opposite trend proving that the fluorination effect on the volatility of the studied ionic liquids is ruled by the increase of the entropy of vaporization that overlaps the increase of the cohesive energy of the liquids. The binding energies of gas-phase FILs ions were measured using electrospray tandem mass spectrometry (ESI-MS-MS). The energy required for extracting the fluorinated cation from the [(cation)2(anion)]+ aggregates in these fluorinated ionic liquids is significantly higher than in their non-fluorinated counterparts. The measured binding energies trends are in agreement with those found for the enthalpies of vaporization.

Semiclassical method of analysis and estimation of the orbital binding energies in many-electron atoms and ions

Orbital binding energies in the ground state of many-electron elements obtained in experiments or in quantum-mechanical-calculations are studied. Their dependences on the atomic number and on the degree of ionization are analyzed. The Bohr – Sommerfeld semiclassical quantization condition is used and filled-shell orbital binding energy approximate scaling is shown. The scaling is similar to the one in the Thomas – Fermi model, but with two other functions-coefficients. The effective method of the demonstration of binding energies in a large number of atoms through these two functions is proposed. As a result, special features of the elements of the main and transition groups and the influence of relativistic effects are vividly manifested. Simple interpolation expressions are built for the two functions. One can use them to estimate orbital binding energies in the filled shells of many-electron atoms and ions to within 10% for middle elements and from 10% to 30% for heavy ones. The estimate can be used as the initial approximation in precessional atomic computations and also for rough calculations of the ionization cross sections of many-electron atoms and ions by electrons and heavy particles, failing more precise data.