Alkaline Earth Cations Research Articles

(Digital Presentation) Charge Transfer Kinetics of the Ti(IV)/Ti(III) Redox Couple in the Cesium Chloride-Cesium Fluoride Melt with Addition of Alkaline Earth Metal Cations

The electrochemical behavior of the Ti(IV)/Ti(III) redox couple in the CsCl-CsF(10 wt.%)-K2TiF6 melt was studied. The standard rate constants of charge transfer for the Ti(IV)/Ti(III) redox couple in CsCl-CsF(10 wt.%)-K2TiF6-based melts with additions of alkaline earth metal cations (Mg2+, Ca2+, Sr2+ and Ba2+) were determined by cyclic voltammetry method. The activation energies of charge transfer process were calculated. The linear dependence of charge transfer rate constants on the ionic potential of alkaline earth metal cations was found.

PSXIII-16 Effects of Clay Mineral ‘Illite’ on the Growth Performance, Nutrient Digestibility and Meat-Carcass Grade Quality in Growing-Finishing Pigs

Abstract Clays are crystalline, hydrated aluminosilicate molecules composed of alkali and alkaline earth cations along with small amounts of various other elements. The best-known are montmorillonite, smectite, illite, kaolinite, biotite and clinoptilolite. Such illite was used in this present study to investigate its effects on the growth performance, nutrient digestibility and meat-carcass grade quality in growing-finishing pigs. A total of 150 pigs (Landrace × Yorkshire × Duroc); weighted 25.42 ± 3.23kg, were selected and randomly allocated to 2 treatments with 15 replicates per group and 5 pigs per replicates according to initial body weight and sex. The experimental treatments consisted of corn-soybean meal-based basal diet (CON) and basal diet supplemented with 0.5% illite (IL). The experiment period lasted for 126 days. Pigs fed IL supplemented diet had greater (P<0.05) average daily feed intake (ADFI) and reduction in G:F during 43 to 70 and 99- 126 days compared with pigs fed CON diet. The apparent total tract digestibility (ATTD) of dry matter (DM) was greater during day 42 and 126 in pigs receiving IL supplemented diet compared with CON diet. The inclusion of IL in the diet of the pigs had increased (P< 0.05) backfat thickness (BFT) during day 98 while drip loss was decreased (P < 0.05) on day 7 and showed tendency (P=0.088) to increase the meat firmness. Therefore, we concluded that supplementation of 0.5% of IL in diets could improve growth performance, total tract digestibility of dry matter, and meat quality in growing-finishing pigs

New mixed ligand complexes of alkaline earth metal cations containing nicotinamide and diphenic acid. Synthesis and structural properties

Mixed-ligand coordination compounds containing neutral nicotinamide and monoanionic diphenate organic molecules of alkaline earth metal cations, Mg2+ (C40H38MgN4O14) (I), Ca2+ (C40H34CaN4O2) (II), Sr2+(C40H34N4O2Sr) (III) and Ba2+(C40H34BaN4O2) (IV) were synthesised. Chemical composition analysis, single crystal XRD, spectroscopic, and thermal analysis methods were used to determine the structural properties of the compounds obtained. According to the data obtained from a single-crystal XRD analysis of the Mg2+ complex, the coordination environment of the metal cation was surrounded by four aqua and two nicotinamide ligands to form a distorted octahedral geometry. The charge balance of the complex sphere was provided by two diphenate ligands placed mono-anionically outside the coordination sphere. The structure is a salt-type complex. Since crystals suitable for single crystal structure analysis of other metal cations complexes (II, III and IV) could not be formed, the structural properties were tried to be explained by chemical composition analysis, spectroscopic, and thermal analysis methods. Accordingly, it is found that the coordination circles of metal cations are octahedral and all ligands (two aqua, two neutral nicotinamide, and two monoanionic-double-toothed diphenate) coordinate with the metal in the coordination sphere. The geometries of the complexes are detected to be of distorted cubic structure.

Mechanisms of dispersion of metakaolin particles via adsorption of sodium naphthalene sulfonate formaldehyde polymer

The influence of different alkali and alkaline earth cations (Na+, K+, Ca2+, and Mg2+), and of solution pH, on surface interactions of metakaolin particles with a sodium naphthalene sulfonate formaldehyde polymer (SNSFP) (a commercial superplasticizer for concretes) was investigated in aqueous systems relevant to alkali-activated and blended Portland cements. This study used zeta potential measurements, adsorption experiments, and both in situ and ex situ Fourier transform infrared spectroscopy measurements of the suspensions to gain a fundamental understanding of colloidal interactions and physicochemical mechanisms governing dispersion in this system. SNSFP was most effective in dispersing metakaolin suspensions in Ca2+-modified aqueous NaOH systems (CaCl2-NaOH) at dosages of 5 wt.%. Additionally, Ca2+ was the most effective alkaline earth cation mediator in providing a dispersion effect in metakaolin dispersed in aqueous NaOH and SNSFP mixtures, while Mg2+ was the most effective in aqueous KOH and SNSFP mixtures. The colloidal dispersion remained stable in the highly alkaline environment, and therefore SNSFP could be utilized to improve dispersion of metakaolin-based alkali-activated systems. The suggested mechanism for colloidal stability and fluidity of metakaolin-based cements (e.g. Portland cement blends and alkali-activated cements) is explained by changes in the distribution and structure of the electric double-layer, as well as structural forces, due to alteration in surface charge density and hydrated shell, facilitating competitive adsorption of the polymer.

Bi and Sn Doping Improved the Structural, Optical and Photovoltaic Properties of MAPbI3-Based Perovskite Solar Cells

One of the most amazing photovoltaic technologies for the future is the organic–inorganic lead halide perovskite solar cell, which exhibits excellent power conversion efficiency (PCE) and can be produced using a straightforward solution technique. Toxic lead in perovskite can be replaced by non-toxic alkaline earth metal cations because they keep the charge balance in the material and some of them match the Goldschmidt rule’s tolerance factor. Therefore, thin films of MAPbI3, 1% Bi and 0%, 0.5%, 1% and 1.5% Sn co-doped MAPbI3 were deposited on FTO-glass substrates by sol-gel spin-coating technique. XRD confirmed the co-doping of Bi–Sn in MAPbI3. The 1% Bi and 1% Sn co-doped film had a large grain size. The optical properties were calculated by UV-Vis spectroscopy. The 1% Bi and 1% Sn co-doped film had small Eg, which make it a good material for perovskite solar cells. These films were made into perovskite solar cells. The pure MAPbI3 film-based solar cell had a current density (Jsc) of 9.71 MA-cm−2, its open-circuit voltage (Voc) was 1.18 V, its fill factor (FF) was 0.609 and its efficiency (η) was 6.98%. All of these parameters were improved by the co-doping of Bi–Sn. The cell made from a co-doped MAPbI3 film with 1% Bi and 1% Sn had a high efficiency (10.03%).

Differences in ion-RNA binding modes due to charge density variations explain the stability of RNA in monovalent salts.

The stability of RNA increases as the charge density of the alkali metal cations increases. The molecular mechanism for this phenomenon remains elusive. To fill this gap, we performed all-atom molecular dynamics pulling simulations of HIV-1 trans-activation response RNA. We first established that the free energy landscape obtained in the simulations is in excellent agreement with the single-molecule optical tweezer experiments. The origin of the stronger stability in sodium compared to potassium is found to be due to the differences in the charge density–related binding modes. The smaller hydrated sodium ion preferentially binds to the highly charged phosphates that have high surface area. In contrast, the larger potassium ions interact with the major grooves. As a result, more cations condense around phosphate groups in the case of sodium ions, leading to the reduction of electrostatic repulsion. Because the proposed mechanism is generic, we predict that the same conclusions are valid for divalent alkaline earth metal cations.

(Keynote) Oxygen Reduction and Evolution in Ca2+ Containing DMSO on Atomically Smooth and Rough Pt and Au – Towards a Generalized ORR Mechanism in M2+ Containing DMSO

We demonstrate via cyclic voltammetry, differential electrochemical mass spectrometry (DEMS) and rotating ring disk electrode (RRDE) investigations with variation of the electrode surface roughness and atomically surface structure, that the CaO/CaO2 adsorbate layer formation determines the ORR product distribution. We found that on Pt electrodes peroxide is formed on the clean electrode, whereas superoxide is formed at the adsorbate covered electrode. We furthermore identified four key parameters, which strongly affect the ORR product distribution. The electrode oxide interaction: A strong interaction shifts the product distribution to larger superoxide contribution.The alkaline earth metal oxide interaction: A strong interaction shifts the product distribution to larger peroxide contribution.The electrode surface area: A large electrode surface area delays the completion of the adsorbate layer and increases the peroxide contribution.Electrode surface defects: Defects allow for faster nucleation and thus foster the adsorbate formation, which finally leads to a larger superoxide contribution. Finally, reviewing earlier results of our group we provide a more general mechanism for the oxygen reduction alkaline earth metal cation containing DMSO, for a variety of electrode materials.[1] A. Koellisch-Mirbach, I. Park, M. Hegemann, E. Thome and H. Baltruschat, ChemSusChem, (2021).[2] P.P. Bawol, A. Koellisch-Mirbach, C.J. Bondue, H. Baltruschat and P.H. Reinsberg, ChemSusChem, 14 (2021) 428.

(Invited) In-Situ Nanoscale Coatings on Silicon Anodes

One of the directions being pursued for next generation electrochemical cells is the incorporation of elemental silicon into a lithium-ion battery anode. Silicon's high storage capacity and abundance make it an appealing material for lithium-ion cells. While many studies revolve around its mechanical issues (high volume expansion) and coulombic efficiency on cycling, a major roadblock to its use is its poor calendar life. On standing while charged, silicon based electrodes are observed to lose capacity (active lithium). Since this type of test does not involve particle breakdown, losses due to issues associated with parasitic currents are in part derived from the high reactivity of charged silicon anodes with the surrounding electrolyte and electrode binder. In this talk we will be discussing a new concept that deactivates the redox activity of the silicon surface while maintaining the high lithium-ion conductivity of the highly charged surface phases. We have found that by selectively adding alkaline earth cations to the surface, a more electron precise phase (i.e. Li14MgSi4 vs Li15Si4) forms that acts to change the phase evolution moving away from phases formed by gradual one-electron oxidation in the binary lithium-silicon system. Various studies show that the parasitic currents are seen to drop with addition and cycling with extended calendar life observed. Mechanistic studies will be presented that highlight magnesium addition to the electrolyte and electrode and the role of time on the surface phases.

Efficient, Selective Sodium and Lithium Removal by Faradaic Deionization Using Symmetric Sodium Titanium Vanadium Phosphate Intercalation Electrodes.

NASICON (sodium superionic conductor) materials are promising host compounds for the reversible capture of Na+ ions, finding prior application in batteries as solid-state electrolytes and cathodes/anodes. Given their affinity for Na+ ions, these materials can be used in Faradaic deionization (FDI) for the selective removal of sodium over other competing ions. Here, we investigate the selective removal of sodium over other alkali and alkaline-earth metal cations from aqueous electrolytes when using a NASICON-based mixed Ti-V phase as an intercalation electrode, namely, sodium titanium vanadium phosphate (NTVP). Galvanostatic cycling experiments in three-electrode cells with electrolytes containing Na+, K+, Mg2+, Ca2+, and Li+ reveal that only Na+ and Li+ can intercalate into the NTVP crystal structure, while other cations show capacitive response, leading to a material-intrinsic selectivity factor of 56 for Na+ over K+, Mg2+, and Ca2+. Furthermore, electrochemical titration experiments together with modeling show that an intercalation mechanism with a limited miscibility gap for Na+ in NTVP mitigates the state-of-charge gradients to which phase-separating intercalation electrodes are prone when operated under electrolyte flow. NTVP electrodes are then incorporated into an FDI cell with automated fluid recirculation to demonstrate up to 94% removal of sodium in streams with competing alkali/alkaline-earth cations with 10-fold higher concentration, showing process selectivity factors of 3-6 for Na+ over cations other than Li+. Decreasing the current density can improve selectivity up to 25% and reduce energy consumption by as much as ∼50%, depending on the competing ion. The results also indicate the utility of NTVP for selective lithium recovery.

Locking volatile organic molecules by subnanometer inorganic nanowire-based organogels

The intermolecular forces among volatile organic molecules are usually weaker than water, making them more difficult to absorb. We prepared alkaline earth cations–bridged polyoxometalate nanoclusters subnanometer nanowires through a facile room-temperature reaction. The nanowires can form three-dimensional networks, trapping more than 10 kinds of volatile organic liquids effectively with the mass fraction of nanowires as low as 0.53%. A series of freestanding, elastic, and stable organogels were obtained. We prepared gels that encapsulate organic liquids at the kilogram scale. Through removing solvents in gels by means of distillation and centrifugation, the nanowires can be recycled more than 10 times. This method could be applied to the effective trapping and recovery of organic liquids.

Coarse-grained modeling of the calcium, sodium, magnesium and potassium cations interacting with proteins.

Metal ions play important biological roles, e.g., activation or deactivation of enzymatic reactions and signal transduction. Moreover, they can stabilize protein structure, or even be actively involved in the protein folding process. Therefore, accurate treatment of the ions is crucial to model and investigate biological phenomena properly. In this work the coarse-grained UNRES (UNited RESidue) force field was extended to include the interactions between proteins and four alkali or alkaline earth metal cations of biological significance, i.e., calcium, magnesium, sodium and potassium. Additionally, chloride anions were introduced as counter-ions. Parameters were derived from all-atom simulations and incorporate water in an implicit manner. The new force field was tested on the set of the proteins and was able to reproduce the ion-binding preferences.

PROCESSES OF CHEMICAL WEATHERING OF NEW TYPES OF AGROMELIORANTS

In studies in a model experiment, it was found that in the process of weathering saponite-containing basaltic tuffs, mainly cations K, Ca and Mg are washed out and some alkalinization of the solution occurs.
 In the process of weathering of glauconite, both alkaline and alkaline earth cations K, Ca and Mg, and acid cations Al and Fe actively pass into the solution, which leads to acidification of the solution.
 Differences in the weathering processes of saponite-containing basalt tuffs and glauconite should be taken into account when they are used as agromeliorants in biocenoses.

Metal-Rich Phosphides Obtained from the Lead Flux: Synthesis, Crystal, and Electronic Structure of Sr5Pt12P9 and BaPt3P2.

Using a high-temperature ampoule technique and lead metal as a flux, we have grown single crystals and determined crystal structures from single-crystal X-ray diffraction data of two metal-rich phosphides, Sr5Pt12P9 (P 21/m, a = 6.1472(3) Å, b = 25.1713(13) Å, c = 6.4635(3) Å, β = 99.604(2)°, Z = 2, R1 = 0.0326, wR2 = 0.0786) and BaPt3P2 (P 212121, a = 6.3605(6) Å, b = 6.8541(7) Å, c = 11.3493(12) Å, Z = 4, R1 = 0.0231, wR2 = 0.0501). Both compounds belong to their own structure types and feature 3D networks of Pt and P atoms, with the channels occupied by alkaline earth metal cations. Density functional theory calculations reveal Sr5Pt12P9 to be a metal, while BaPt3P2 is a narrow-gap semiconductor with a band gap of 0.24 eV. Bonding analysis shows that both compounds feature networks of prominent covalent localized Pt-P bonds, responsible for their structural stability, as well as additional weaker and, likely, less localized Pt-Pt interactions.

Electrodialysis of LiH2PO4 for High-Purity LiOH and Green H2 Production

The current soda-lime evaporation process to recover lithium carbonate from continental brines by treatment with Solvay has a low efficiency due to the high solubility of Li2CO3, unlike precipitation of Li3PO4 after removal of alkaline earth cations, which has a very high efficiency. The main goal of this work is to provide a proof of concept for replacing the present method of LiOH.H2O production, i.e. replacing the reaction of Li 2 CO 3 with Ca(OH)2, by a single step electrodialysis of LiH2PO4 from insoluble Li3PO4 with no waste generation, recycling of phosphoric acid, better efficiency than the lithium carbonate pathway and green hydrogen generation. Experimental results have been complemented with numerical simulation of the electro-dialysis system solving the time-dependent concentration and potential profiles for two configurations: two compartments using a cation-selective membrane and a three-compartment cell with cation and anion-selective membranes operating at constant current, along with the voltage evolution and current efficiency for LiOH production.

Twisting DNA by salt.

The structure and properties of DNA depend on the environment, in particular the ion atmosphere. Here, we investigate how DNA twist -one of the central properties of DNA- changes with concentration and identity of the surrounding ions. To resolve how cations influence the twist, we combine single-molecule magnetic tweezer experiments and extensive all-atom molecular dynamics simulations. Two interconnected trends are observed for monovalent alkali and divalent alkaline earth cations. First, DNA twist increases monotonously with increasing concentration for all ions investigated. Second, for a given salt concentration, DNA twist strongly depends on cation identity. At 100 mM concentration, DNA twist increases as Na+ < K+ < Rb+ < Ba2+ < Li+ ≈ Cs+ < Sr2+ < Mg2+ < Ca2+. Our molecular dynamics simulations reveal that preferential binding of the cations to the DNA backbone or the nucleobases has opposing effects on DNA twist and provides the microscopic explanation of the observed ion specificity. However, the simulations also reveal shortcomings of existing force field parameters for Cs+ and Sr2+. The comprehensive view gained from our combined approach provides a foundation for understanding and predicting cation-induced structural changes both in nature and in DNA nanotechnology.

Dendrite-free alkali metal electrodeposition from contact-ion-pair state induced by mixing alkaline earth cation

Alkali metals are expected to be used for rechargeable metal anode batteries owing to their low electrode potentials and large capacities. However, they face the well-known fatal problem of “dendritic growth” while charging. Here, we present a detailed investigation on electrolytes where alkaline earth salts are introduced to inhibit dendrite growth in alkali metal electrodeposition. Specifically, focusing on CaTFSA 2 as an exemplary additive, we reveal that dendrite-free morphology upon alkali metal electrodeposition can be attained by modifying the solvation structures in dual-cation electrolytes. Addition of Ca 2+ promotes alkali cation (Li + or Na + ) to form the contact ion pairs (CIPs) with the counter anions, which replaces the solvent-separated ion pairs that commonly exist in single-cation electrolytes. The strong binding of the CIPs slows the desolvation kinetics of alkali cations and, consequently, realizes a severely constrained alkali metal electrodeposition in a reaction-limited process that is required for the dendrite-free morphology. • Additive divalent cations lead to flat morphology in Li and Na electrodeposition • Li + /Na + tends to form strong CIPs to alleviate interaction among divalent cations • Increased activation energy of CIPs enables to retain a uniform diffusion field Li et al. report that mixing divalent cations with alkali cations in electrolytes can modify the solvation structure and consequently obtain flat morphology in alkali metal electrodeposition. This finding may represent a step toward active control of reaction kinetics toward metal anode batteries.

Electronic sensors for alkali and alkaline earth cations based on Fullerene-C60 and silicon doped on C60 nanocages: a computational study.

In this research, we have reported the electrical sensitivity of pristine C60 and silicon doped on C60 (SiC59) nanocages as sensors that can be used for detecting the presence of alkali (Li+, Na+, K+) and alkaline earth (Be2+, Mg2+, Ca2+) cations. The computations are carried out at the B3LYP level of theory with a 6-31G(d) basis set. The atoms in molecules (AIM) and natural bond orbital (NBO) analyses are performed to evaluate the intermolecular interactions between cations and nanocages. The physical properties of the selected complexes are also analyzed by the frontier molecular orbital, energy gap, electronegativity, chemical hardness, softness, and other quantities such as work function, number of transferred electron, and dipole moment. The results show that the adsorption process is exothermic and with increasing the charge of cations, the adsorption energies enhance. Our findings also reveal a decrease in the energy gap along with an increase in the electrical conductivity of the respective complexes. Finally, the density of state calculations is presented to confirm the obtained results.

Hofmeister Effects of Group II Cations as Seen in the Unfolding of Ribonuclease A.

This work studies the effects of alkaline-earth cation addition on the unfolding free energy of a model protein, pancreatic Ribonuclease A (RNase A) by differential scanning calorimetry analysis. RNase A was chosen because: a) it does not specifically bind Mg2+ , Ca2+ and Sr2+ cations and b) maintains its structural integrity throughout a large pH range. We have measured and compared the effects of NaCl, MgCl2 , CaCl2 and SrCl2 addition on the melting point of RNase A. Our results show that even though the addition of group II cations to aqueous solvent reduces the solubility of nonpolar residues (and enhances the hydrophobic effect), their interactions with the amide moieties are strong enough to "salt-them-in" the solvent, thereby causing an overall protein stability reduction. We demonstrate that the amide-cation interactions are a major contributor to the observed "Hofmeister Effects" of group II cations in protein folding. Our analysis suggests that protein folding "Hofmeister Effects" of group II cations, are mostly the aggregate sum of how cation addition simultaneously salts-out hydrophobic moieties by increasing the cavitation free energy, while promoting the salting-in of amide moieties through contact pair formation.

Towards a Generalized ORR Mechanism in M2+‐Containing DMSO: Oxygen Reduction and Evolution in Ca2+‐Containing DMSO on Atomically Smooth and Rough Pt

AbstractThe oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in Ca2+ containing dimethyl sulfoxide (DMSO) on atomically smooth Pt(111) and Pt(100) and rough Pt surfaces is reported. As demonstrated by cyclic voltammetry and XPS, the bromine adlayer used to protect Pt single crystals against ambient air and solvent vapor is desorbed in DMSO and does not affect the following measurements. Cyclic voltammetry, differential electrochemical mass spectrometry (DEMS), and rotating ring disk electrode (RRDE) investigations with variation of the electrode surface roughness and atomically surface structure show, that on Pt electrodes the CaO2 adsorbate layer formation determines the ORR product distribution. On Pt electrodes, calcium peroxide is formed on the clean electrode, whereas calcium superoxide is formed at the adsorbate covered electrode. We furthermore identified four key parameters, which strongly affect the ORR product distribution: 1) The electrode oxide interaction: A strong interaction increases superoxide contribution; 2) The alkaline earth metal oxide interaction: A strong interaction increases peroxide contribution; 3) The electrode surface area: A large electrode surface area increases peroxide contribution; 4) Electrode surface defects: Defects increase superoxide contribution. Finally, reviewing earlier results of our group, we provide a more general mechanism for the oxygen reduction alkaline earth metal cation containing DMSO, for a variety of electrode materials.

Optoelectronic Properties Prediction of Lead-Free Methylammonium Alkaline-Earth Perovskite Based on DFT Calculations.

Dynamical stability plays an essential role in phase transition and structure, and it could be a fundamental method of discovering new lead-free perovskite materials. The perovskite materials are well-known for their excellent optoelectronic properties, but the lead element inside could be a hindrance to future development. This research is trying to predict the promising cation candidates in the high-temperature application for lead-free perovskite materials from the replacement of lead in MAPbCl3 (MA = methylammonium) with alkaline-earth cations. The alkaline-earth cations are of a stable positive divalent sort, which is the same as Pb, and most of them are abundant in nature. Therefore, by improving the dynamical stability, the Mg2+, Ca2+, and Sr2+ cations replacement of lead ions could stabilize the perovskite structure by decreasing the imaginary part of phonon density of states. Finally, the density functional theory results show that the MACaCl3 could be a dynamic stable lead-free methylammonium perovskite material with an ultrawide band gap (5.96 eV).