Sodium Bis Research Articles

Safe sodium‐ion battery using hybrid electrolytes of organic solvent/pyrrolidinium ionic liquid

AbstractIonic liquids (ILs) have been considered as an alternative class of electrolytes compared to conventional carbonate solvents in rechargeable lithium/sodium batteries. However, the drawbacks of ILs are their reducing ionic conductivity and their large viscosity. Therefore, mixtures of alkyl carbonate solvents with an IL and a sodium bis(trifluoromethane sulfonyl)imide (NaTFSI) have been investigated to develop new electrolytes for sodium‐ion batteries. In this work, N‐Butyl‐N‐methylpyrrolidinium bis(trifluoro‐methanesulfonyl) imide (Py14TFSI) was used as co‐solvent mixing with commercial electrolytes based on the carbonate, i.e. EC‐PC (1:1), EC‐DMC (1:1), and EC‐PC‐DMC (3:1:1). The addition of ionic liquid in the carbonate‐based electrolyte solution results in (i) enhancing ionic conductivity to be comparable with a solvent‐free IL‐based electrolyte, (ii) maintaining the electrochemical stability window, and (iii) IL acted as a retardant rather than a flame‐inhibitor based on the self‐extinguish time (SET) of the mixed electrolyte mixture when exposed to a free flame. All mixed electrolyte systems have been tested in sodium‐coin cells versus Na0.44MnO2 (NMO) and hard carbon (HC) electrodes. The cells show good performances in charge/discharge cycling with a retention > 96 % after 30 cycles (∼90 mAh.g‐1 for NMO and 180 mAh.g‐1 for HC, respectively) demonstrating good interfacial stability and highly stable discharge capacities.

DIAMETER OF SODIUM DI-(2-ETHYLHEXYL)PHOSPHATE AND SODIUM DODECYLSULFATE REVERSE MICROEMULSION DROPLETS: EXPERIMENTAL DATA AND CALCULATION METHODS

The article is concerned with study of diameters of reverse microemulsion droplets depending on the water content in sodium bis-(2-ethylhexyl)phosphate – decane – water and sodium dodecylsulfate – butanol-1 – decane – water systems. Hydrodinamic diameters of microemulsion droplets were determined by the method of dynamic light scattering. It increases from 5.9 to 9.7 nm with an increase in the molar ratio of water and sodium bis-(2-ethylhexyl)phosphate from 5.0 to 20.0 in the sodium bis-(2-ethylhexyl)phosphate – decane – water microemulsion. Diameter of microemulsion droplets in the sodium dodecylsulfate – butanol-1 – decane – water system increases from 2.4 to 8.6 nm with an increase in the molar ratio of water and dodecylsulfate from 7.5 to 30.0. It was shown that the dependence of the diameter (d) on the water content (W) is linear. The applicability of the experimental data on the area per surfactant molecule at the "water-oil" interface and literature data on the values of molar volumes of microemulsion components to calculate the diameter of microemulsion droplets was analyzed. It was shown that the equation of the form d = kW + b is suitable for describing the dependence of the diameter of microemulsion droplets on the water content in the sodium dodecyl sulfate-butanol – 1-decane-water system. Parameters k and b of this equation are calculated using the value of the area per surfactant molecule at the "water-oil" interface, which can be obtained from experimental data on interfacial tension. Values of the diameter of microemulsion droplets calculated using the proposed equation differ by no more than 1 nm from the values obtained by dynamic light scattering. Values of the droplet diameter of microemulsion in the DEHPA – decane – water system calculated using this equation are underestimated by 1.0-2.5 nm relative to the experimental values, while the slope of the lines obtained from the experimental data and during the calculation is almost the same.

Catalytic performance of boron-containing magnetic metal nanoparticles in methylene blue degradation reaction and mixture with other pollutants

The catalytic effects of metal nanoparticles (MNPs) synthesized in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) microemulsion system by using M(II) salts (M = Fe, Co, Ni) and NaBH4 reducing agent on methylene blue (MB) degradation reaction were investigated. It was determined that Co-MNPs gave the best catalytic activity among them. Influence of the reaction parameters e.g., reaction time, temperature, the size of catalyst and the MNP types on the catalytic performance were studied. It was found that 37 ± 6 nm Co-MNPs revealed the best catalytic activity in all studies. The best activation parameters were calculated as 13.6 ± 1.1 kJ mol−1 and ΔH = 10.7 ± 1.0 kJ mol−1 and ΔS = -87.9 ± 5.4 J mol−1 K−1. The activity % of Co-MNPs was calculated as 85.4 after 30 days on the shelf life study. The reusability studies were carried out and the activity of Co-MNPs at the 5th reuse was calculated as 70 ± 5%. Finally, the catalytic activity of Co-MNPs was investigated inside equal volumes of single and multiple solution mixtures containing MB, 4-Nitrophenol (4-NP) and Eosin Y (EY). In the examinations, it was observed that the nanocatalyst was effective as a reducing agent in all equal amount solutions (MB/4-NP, MB/EY, 4-NP/EY, and MB/4-NP/EY). And also, TOF (mole of MB/4-NP/EY) (mol catalyst.min)−1 values ​​of catalytic activities were also calculated.

Effect of Surfactants’ Tail Number on the PVDF/GO/TiO2-Based Nanofiltration Membrane for Dye Rejection and Antifouling Performance Improvement

In this work, the novel utilisation of customised double- and triple-tail sodium bis(3,5,5-trimethyl-1-hexyl) sulphosuccinate (AOT4) and sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-silphonate (TC14) surfactants to assist the direct graphene oxide (GO) synthesis via electrochemical exfoliation utilising dimethylacetamide (DMAc) as a solvent were investigated. The synthesised DMAc-based GO and titanium dioxide (TiO2) nanoparticles were then used to fabricate polyvinylidene fluoride (PVDF)-based nanofiltration (NF) membranes by the non-solvent-induced phase separation method. The incorporation of GO and TiO2 as hydrophilic nanoparticles were to enhance membrane hydrophilicity. The utilisation of higher surfactants’ tail number obviously alters the fabricated membrane’s morphology which further affects its performance for dye rejection and antifouling ability. Higher surfactants’ tail number resulted in higher oxidation process which then provided more interaction between the GO and PVDF. Based on the dead-end cell measurement, PVDF/TC14-GO/TiO2 presented a slightly higher dye rejection efficiency of 92.61% as compared to PVDF/AOT4-GO/TiO2 membrane (92.39%). However, PVDF/TC14-GO/TiO2 possessed three times higher water permeability (48.968 L/m2 h MPa) than PVDF/AOT4-GO/TiO2 (16.533 L/m2 h MPa) and also higher hydrophilicity as presented by lower contact angle (65.4 ± 0.17°). This confirmed that higher surfactants’ tail number improved the fabricated membrane’s performance. Both fabricated membranes also exhibited high flux recovery ratio (FRR) ( $$>$$ 100%) which indicated better antifouling properties.

Influence of amphiphilic molecules on the peroxidase-like behavior of nanoparticles in an aqueous solution.

Carbon dots (CDs) have drawn considerable attention in recent decades due to their outstanding biocompatibility and environmental friendliness. In this study, we synthesized ionic liquid (1-aminopropyl-3-methyl-imidazolium bromide)-modified carbon dots (IL-CDs) showing good peroxidase-like activity. Furthermore, we investigated their enzymic behavior in the presence of two different amphiphilic molecules, namely tert-butanol (TBA, a typical hydrotrope) and sodium bis (2-ethylhexyl) sulfosuccinate (AOT, a typical anionic surfactant). In an aqueous solution of TBA, a microscopic heterogeneous structure was formed in a certain concentration range of TBA, which resulted in an anomaly in the reaction process. However, in the AOT aqueous solution, the situation became more complicated. IL-CDs formed vesicles or precipitation at different concentrations of AOT, which led to different enzymic activities of IL-CDs due to the variance in the structure and the surface electronic density.

Does Confinement Modify Preferential Solvation and H-Bond Fluctuation Dynamics? A Molecular Level Investigation through Simulations of a Bulk and Confined Three-Component Mixture.

Exploring the local environment around a dissolved solute in a bulk aqueous solution of alcohol and assessing the impact of confinement on the solvation structure is an important topic yet is much less studied. Such a study is important because it can provide critical information regarding the miscibility of an amphiphilic drug after delivery at a designated nanoscopic site and the subsequent release. The present molecular dynamics simulation study reports an in-depth investigation of the composition-dependent solvation structure around a dissolved hydrophobic solute, coumarin 153 (C153), in ambient binary mixtures of methanol and water in both bulk and under confinement. The confinement is a spherical sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelle with a diameter of 55 Å. Inter- and intraspecies H-bond fluctuation dynamics have been monitored and compared with those from the corresponding bulk binary mixtures. A systematic comparison of both solvation structure and H-bond dynamics between confined and bulk binary mixtures reveals modulation of both preferential solvation and H-bond relaxation times inside a nanoscopic environment. More specifically, confinement accentuates the preferential solvation phenomenon and facilitates di-mixing of mixture components. In addition, the present study reveals that the tetrahedral H-bond network of neat liquid water becomes severely affected upon addition of methanol, which becomes further distorted under confinement. Confinement severely affects the interspecies hydrogen bonds and makes the corresponding continuous hydrogen bonds much shorter-lived. Interestingly, structural hydrogen bond relaxation timescales become longer in confined binary mixtures than those in bulk binary mixtures.

Bromophenol blue doped in nano-droplet: spectroscopy, nonlinear optical properties and Staphylococcus aureus treatment

Bromophenol blue (BPB)-doped nano-droplets are recognized as a synthesis of BPB dye and transparent dispersion of nano-droplets (ND), in a continuous phase of oils. In this regard, to discover the effect of ND size on nonlinear optical properties of BPB, a solution of BPB-doped ND with heptane oil and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as a surfactant has been prepared and therefore investigated with Z-scan technique. The consequences have revealed that the nonlinear refractive (NLR) index, of the BPB-doped ND has been improved by comparison with BPB aqueous solution. The second-order hyperpolarizability of the BPB-doped ND has been also reduced subsequent a reduction in ND size owing to reducing dye aggregation. Moreover, the BPB-doped ND in the company of laser radiation has been utilized in order to study of antibacterial photodynamic therapy of Staphylococcus aureus (S. aureus) by nonlinear absorption. As a consequence, the bacteria colonies have been also exceedingly declined in the group treated with the BPB-doped ND.

Surface Change of Liquid Ga Electrode By Na Electrodeposition in NaTf2N-TEATf2N Ionic Liquid

A liquid metal electrode has interesting property such as phase change from a liquid to a solid depend on alloys composition. There are many reports of solid metal deposition on a liquid electrode, there are few papers of liquid metal deposition on a liquid electrode. In this study, Ga was used as the liquid electrode and Na electrodeposition was carried out in ionic liquid electrolyte at 160 oC. Since the melting point of Ga and Na are 29.8 and the 97.8 oC, at the moment when Na is electrodeposited, the liquid Na presents on the liquid Ga. In this experiment, we focused on the surface change of the Ga electrode before and after the electrodeposition of liquid Na.The experiment was conducted in a glove box under Ar atmosphere. NaTf2N (Sodium bis (trifluoromethanesulfonyl) imide) -TEATf2N (Tetraethylammonium bis (trifluoromethanesulfonyl) imide) mixed ionic liquid with molar ratio of 1 : 4 was used as an electrolyte at 160 oC. Liquid Ga or solid Ag plate was used as a working electrode and liquid Na was used as counter electrode and reference electrode. The voltammogram measurement was performed in the range from 2.5 V to -0.5 V (vs. Na/Na+) with sweep rate of 10 mV s-1. Constant current electrolysis was carried out at 5 mAcm-2 for 3 minutes. The liquid Ga electrode surface was taken by a digital camera. The time change of the open circuit potential of the Ga electrode after constant current electrolysis was measured by potentiostat.In voltammogram measurement, cathodic current on Ag working electrode flowed at lower than 0.0 V (vs. Na / Na +). In the liquid Ga electrode, cathodic current started at 0.6 V, then the cathodic current increased again at lower than about 0 V. The color of the liquid Ga surface changed slightly from bright metallic to black and gray. When the potential was reversed to anodic direction, the color of the Ga surface changed to gray, black and bright metallic. In liquid Ga electrode, start of cathodic current was more positive potential compared with solid Ag electrode. It is considered the cathodic current at range from 0.0 to 0.6 V may relate to formation of Na-Ga intermetallic compound. In constant current electrolysis, the potential change showed in two steps with similar the voltammogram measurement, color of the Ga surface changed to black in the first step and gray in the second step.In the open-circuit potential measurement, 3 potential plateaus of 1.9, 0.58, and 0.38 V (vs. Na / Na +) were observed. The potential plateau at 1.9 V corresponds to pure Ga, the potential plateaus 0.58 and 0.38 V may correspond to Na-Ga intermetallic compounds with different composition. It is known from the Na-Ga binary phase diagram that there are two intermetallic compounds, Ga4Na and Ga39Na22. In the surface color change of Ga electrode to black, it is considered that formation of Ga4Na on the surface because small amount of Na liquid was electrodeposited on the Ga electrode. Further, by depositing Na on the surface, Ga39Na22 may be formed on the surface, and even if more Na is deposited on Ga39Na22, the intermetallic compound does not change any more, and metal Na is deposited on the Ga39Na22. Therefore, the color of the electrode surface may have changed from black to gray.

Sodium-Ion Transfer Reaction at the Interface between Carbon Nanosphere Electrodes and Electrolytes

Introduction Sodium-ion batteries (SIBs) are widely focused on as post lithium-ion batteries from the view of element strategy[1]. Hence, SIBs are attractive for large scale energy storage like electric vehicles. For the large scale energy storage, batteries with high rate capability are desired. Carbon nanosphere (CNS) covered with basal planes is expected as the candidate for carbon negative electrode material with high rate capability because CNS electrodes showed the high rate capability in LIBs owing to small particle sizes and short diffusion distances[2]. To enhance the rate capability of electrode materials, the internal resistances of electrodes should be investigated. In LIBs, the interfacial lithium-ion transfer at the interface between electrodes and electrolytes is one of the rate determining step[3]. However, the kinetic properties of interfacial sodium-ion transfer at the interface between carbon negative electrodes and electrolytes is unclear. In this study, the activation energies of interfacial sodium-ion transfer reaction at the interface between CNS electrodes and organic electrolyte solutions were evaluated. Experimental Electrochemical measurements were carried out using a three-electrode cell. Working electrode was CNS composite electrode. CNS treated at 1100°C and 2900°C were used and denoted as CNS-1100 and CNS-2900, respectively. Reference electrode was Ag/Ag+ electrode and counter electrode was natural graphite composite electrode. The electrolyte solutions were 0.9, 4 mol kg- 1 sodium bis(trifluoromethanesulfonyl)amide (NaTFSA)/ethylene carbonate (EC) + dimethyl carbonate (DMC) (1:1 by vol.) and 0.7 mol kg- 1 NaTFSA/fluoroethylene carbonate (FEC). Hereafter, all potentials are referred to as Fc/Fc+. Cyclic voltammetry (CV) was conducted between open circuit potential (OCV) and various potentials, and the scan rate was set at 0.1 mV s−1. Electrochemical impedance spectroscopy (EIS) was carried out with ac amplitude of 10 mV in a frequency range of 100 kHz − 10 mHz at temperatures ranging from 30°C to 10°C. Results Figure 1 shows the cyclic voltammograms of CNS-1100 composite electrodes in 0.9 mol kg- 1 NaTFSA/EC+DMC(1:1 by vol.). The irreversible currents were observed below −2 V and more than half of the irreversible currents disappeared from the 2nd cycle, indicating the formation of solid electrolyte interphase on CNS electrodes at the same manner of lithium ion-system. The redox peaks also appeared around −3 V, and were assigned to the peaks of reversible sodium-ion insertion into/from CNS-1100. Figure 2 shows the Nyquist plots of CNS-1100 composite electrode in 0.9 mol kg−1 NaTFSA/EC+DMC(1:1 by vol.). In the Nyquist plots, based on the potential dependence of the semi-circle, the semi-circle at the middle frequency region was assigned to the charge-transfer resistance. The same kinds of electrochemical behaviors were observed in the cases of other electrolytes and CNS-2900 electrodes.In the meeting, the activation energies of interfacial sodium-ion transfer will be reported. Acknowledgement This work was partially supported by ESICB, Kyoto University.

The influence of the addition of anionic sodium bis-(2-ethylhexyl) sulfosuccinate on washing properties of liquid laundry detergents

Detergency of liquid laundry detergents (L1, L2) before and after the addition of anionic surfactant sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) was determined using colorimetric analysis based on the CIELab system. Standard cotton fabrics soiled with carbon black and olive oil were used in washing processes under the following conditions: the concentration range of detergents 1.25–50 g/L, water hardness 5.35 mval/L, 40 °C, rotational speed 200 rpm, 30 min washing cycle. Organoleptic and physicochemical properties of tested detergents as well as construction parameters of cotton fabrics were examined using a number of analytical methods. The research showed a gradual increase in detergency with laundry detergents and surfactants concentration. The modification with AOT had a positive effect on washing effectiveness by about 1.9% (AOT-L1) and 3.3% (AOT-L2) on average, as well as a significant reduction in foaming capacity of solutions. A synergistic effect was found through the interaction of all ingredients in solutions with higher concentrations. Based on the microscopic analysis, it was indicated that no damage occurred to the cotton textiles, but the presence of slight fraying of individual fibers. The research results suggest that enriching detergent compositions with a small amount of AOT favorably affects detergency efficiency, which may translate into practical application in industry in the future.

Foam Destabilization Effect of Sodium Bis(2-ethylhexyl)sulfosuccinate on Sodium Alkylsulfate Aqueous Solutions Based on Its Fast Surface Tension Gradient Relaxation

Abstract This study investigated the relationship between the air–water interfacial dilational viscoelasticity and foam properties in mixed anionic surfactant aqueous solutions of sodium bis(2-ethylhexyl)sulfosuccinate (AOT), sodium n-dodecylsulfate (C12AS), sodium n-tetradecylsulfate (C14AS), and sodium n-hexadecylsulfate (C16AS). The surfactants used here differ only in hydrophobic chains. The air–water interfacial viscoelasticity of AOT aqueous solutions mixed with C12AS or C14AS was similar to that of AOT single aqueous solutions at the same constituent concentration of AOT. On the other hand, the air–water interfacial viscoelasticity of mixed aqueous solutions of AOT and C16AS was intermediate between the respective single aqueous solutions. The foam properties of these mixed aqueous solutions were evaluated by a modified Ross–Miles method and it was shown that foam stability is correlated with the maximum value of viscoelastic modulus in mixed aqueous solutions of AOT and AS.

Conductance Study of Aerosol-OT in Binary Mixed Solvents of Short-Chain Alcohol–Water Systems at Various Temperatures

The conductivity of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) is measured in binary mixed solvent media containing 0.000, 0.080, 0.252, and 0.440 mass fractions of methan...

The synergistic role of silica nanoparticle and anionic surfactant on the static and dynamic CO2 foam stability for enhanced heavy oil recovery: An experimental study

CO2 foam is a promising candidate in enhanced oil recovery and reducing anthropogenic CO2 emission through geo-sequestration due to its CO2 mobility control ability. However, instability of CO2 foam stabilized solely by surfactant strongly retards its application. Here, two types of silica nanoparticles (NPs) with varied hydrophobicity are used with sodium bis(2-ethylhexyl) sulfosuccinate (AOT) to increase CO2 foam stability. Through foamability and foam stability experiments, together with complementary experiments such as measurements of CO2-water interfacial tensions, particle zeta potential, and adsorption isotherm of surfactant, the stabilization mechanisms of AOT-NPs aqueous dispersions on the CO2 foam films are revealed. Oil recovery experiments are performed in an oil-wet micromodel where high permeability channels are included to mimic wormholes in unconsolidated sandstone reservoirs during sand production. Results show that the nanoparticle surface hydrophobicity strongly influences the interactions between particles and AOT. Partially hydrophobic NPs (NPB) are much more efficient in generating and stabilizing CO2 foam than hydrophilic NPs (NPA) when mixed with AOT in a proportion of 1: 0.16 (wt%/wt%). AOT-NPB dispersions improve the recovery in two aspects: First, the synergistic interactions between AOT and NPB leads to the adsorption of AOT on particle surfaces, thus enhancing mechanical strength of bubbles. High quality foam encompasses a fine foam texture and provides higher resistance to the gas flow, leading to a more uniform sweep. Second, AOT-NPB dispersions reduces oil/water IFT, promotes emulsification forming oil in water (O/W) emulsions, and alters glass surface wettability, leading to substantial incremental oil recovery.

Luminescence Spectral Characteristics of Markers of the Fluorescein Family in Reverse Micelles of Various Sizes

The luminescence spectral characteristics of eosin, erythrosine, and rose Bengal molecules in reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate were investigated. Inclusion of the dye molecules in the reverse micelles leads to an increase of their hydrodynamic radii Rh, and a linear relationship is observed between this increase ΔRh and the degree of hydration w. The increase of Rh leads to shift in the absorption and fluorescence spectra and increases the Stokes shift. The ratio of the dipole moments of the molecules in the excited and ground states μe/μg increases with increase of Rh.

Structural, spectral and nonlinear optical analysis of Sodium bis(2-methyllactato)borate: a new semiorganic crystal for photonic applications

Semiorganic single crystals of Sodium bis(2-methyllactacto)borate (NaMB) have been grown using solvent evaporation process. NaMB crystal comprises a bis(2-methyllactato)borate anion and a sodium cation. Powder XRD pattern reveals the good crystallinity. Linear optical transmittance window is found to be 215–1100 nm. Na⋯O–C intermolecular interaction is observed in the grown crystal and it is established by observed vibrational frequencies. Functional group associated with borate is well addressed through the vibrations observed in FTIR and FT-Raman spectroscopy. 13C NMR spectroscopy enunciates the position of carbon atoms in the crystal structure. Intermolecular interactions such as Na1⋯O6–C5 and Na1⋯O1–C1 where O6 and O1 are uncoordinated oxygen atoms of carboxylato groups which pulls the electrons from C5 and C1 and causes deshielding effect resulting in shifting of C5 and C1 signals towards higher ppm. These interactions are also established through the shifts observed in 1H NMR spectroscopy. The third order nonlinear susceptibility (χ3) value is 1.07911 × 10−6 esu and this larger value is due to electron delocalization in carboxylato group and charge transfer due to intermolecular interaction present in the crystal structure. The self-focussing and saturable absorption nature of the crystal may be utilized in optical sensors and Q-switching applications.

Ionic Liquid Electrolytes for Safer and More Reliable Sodium Battery Systems

Na+-conducting, binary electrolytic mixtures, based on 1-ethyl-3-methyl-imidazolium, trimethyl-butyl-ammonium, and N-alkyl-N-methyl-piperidinium ionic liquid (IL) families, were designed and investigated. The anions were selected among the per(fluoroalkylsulfonyl)imide families. Sodium bis(trifluoromethylsulfonyl)imide, NaTFSI, was selected as the salt. The NaTFSI-IL electrolytes, addressed to safer sodium battery systems, were studied and compared in terms of ionic conductivity and thermal stability as a function of the temperature, the nature of the anion and the cation aliphatic side chain length. Room temperature conductivities of interest for sodium batteries, i.e., largely overcoming 10−4 or 10−3 S cm−1, are displayed. Similar conduction values are exhibited by the EMI-based samples even below −10 °C, making these electrolyte mixtures potentially appealing also for low temperature applications. The NaTFSI-IL electrolytes, with the exception of the FSI-ones, are found to be thermally stable up to 275 °C, depending on the nature of the cation and/or anion, thus extending their applicability above 100 °C and remarkably increasing the reliability and safety of the final device, especially in the case of prolonged overheating.

Acacia Gum Hydrogels Embedding the In Situ Prepared Silver Nanoparticles; Synthesis, Characterization, and Catalytic Application

Hydrogels of Acacia gum (AG) were synthesized in the reverse micelle core of sodium bis (2-ethylhexyl) sulfosuccinate (AOT) in gasoline medium. The as synthesized hydrogels were used as template to prepare Silver nanoparticle (AgNPs) in situ via the reduction mechanism of NaBH4. The successful synthesis of bare hydrogels and AgNPs loaded nanocomposite hydrogels (AG–Ag hydrogels) were characterized through Fourier Transform Infrared spectroscopy, Thermal gravimetric analysis, Differential Scanning Calorimetry, Scanning Electron Microscopy, energy dispersive X-ray spectroscopy and Transmission Electron Microscopy, and Atomic Absorption Spectroscopy (AAS). Different feeds of the as fabricated GA-Ag hydrogels were used to catalyze the well-known reactions of 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), and Methyl Orange (MO) reduction in aqueous medium at ambient physical conditions. Remarkably, 1000 mg/L of AG–Ag hydrogels with reduced 4-NP and 2-NP into its counterparts, 4-aminophenol and 2-aminophenol in 24 min and 15 min, respectively at room temperature. Similarly, 1000 mg/L of AG–Ag hydrogels reduced MO completely within 25 min. The aforementioned catalytic reactions followed pseudo first order rate kinetics, and it was found that the value of rate constant (kapp) increased by increasing the catalyst amount which, thereby confirms the high conversion rate of the reactants. Schematic illustration of fabrication and catalytic action of AgNPs grown inside the pre-synthesized AG Hydrogel matrices.

Phase Stability and Miscibility in Ethanol/AOT/n-Heptane Systems: Evidence of Multilayered Cylindrical and Spherical Microemulsion Morphologies.

We describe the effects of ethanol on the phase behavior of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in n-heptane. Using dynamic light scattering (DLS), molecular dynamics (MD) simulations, and nuclear magnetic resonance (1H NMR) spectroscopy, we investigate the aggregation behavior of AOT across a wide range of ethanol/AOT/n-heptane compositions. We conclude that reverse micelles do not form at any of the investigated concentrations. Instead, we observe the formation of other surfactant aggregate morphologies unique to this system, namely, multilayered cylindrical structures and spherical AOT-in-ethanol structures, which vary significantly with changes in ethanol concentration. We also identify mixed-solvent polarity as a driving factor for the surfactant behavior in the system. When the concentration of ethanol is 20 wt % or below, the system is inhomogeneous with varying sizes of AOT, ethanol, and AOT + ethanol aggregates, with the ethanol primarily exhibiting a cosurfactant behavior, almost exclusively binding at the surface of AOT aggregates. With increased ethanol concentration, the ethanol in the system also exhibits solvent-like behaviors in addition to the cosurfactant behaviors. Most significantly, when the ethanol concentration is raised above 35 wt %, the transition to solvent-like behavior allows AOT Na+ counterions to dissociate from the headgroups and they are dissolved in the ethanol. We use these results to construct a preliminary phase diagram for the ethanol/AOT/n-heptane system.

Ionic conductance and viscous drag in water-in-salt electrolytes for lithium and sodium ion batteries and supercapacitors

The electrochemical window of water can expanded to ∼3 V using water-in-salt electrolytes (WiSE), which make use of high concentrated aqueous solution of lithium and sodium salts as electrolytes for batteries as well as supercapacitors. In order to understand the dynamics present in these solutions and the effect of temperature on conductance, we performed classical molecular dynamics simulations of WiSE systems: ∼10 m aqueous lithium and ∼8 m sodium bis(trifluorosulfonimide)(LiTFSI and NaTFSI). We find the ionic correlation is weaker in NaTFSI electrolyte and it has more ionic conductivity. However, both aqueous LiTFSI and NaTFSI exhibit much higher ion transport than non-aqueous electrolytes. The viscous drag experienced by NaTFSI is much lesser than that by that of LiTFSI. From the calculations of shear viscosity and the associated activation energy of these electrolyte systems, we find that LiTFSI possess a more substantial energy barrier. The opposite ions stay paired for a shorter period at higher temperatures and contribute to conductivity through their fast motion. The ionic conductivity and viscosity are connected to the lifetime of ion-cage formation, which facilitates the overall dynamics of the electrolyte. We conclude that these WiSE systems are impressive candidates that may produce a paradigm shift in the arena of electrolytes for energy storage devices.

Structure and conductivity of AOT solutions in n-hexadecane-chloroform mixtures.

The structure and conductivity of AOT (sodium bis(2-ethylhexyl) sulfosuccinate) solutions (2.5 × 10-4 -2.5 × 10-1 M) in n-hexadecane-chloroform mixture at the chloroform concentration from 50 to 100 vol% were studied. The diffusion ordered spectroscopy NMR study revealed that in the indicated range, the observed hydrodynamic diameter of micelles depends only on the AOT concentration and does not depend on the chloroform content. Molar fractions of free AOT molecules and those aggregated into micelles were calculated using the Lindman's law: at concentrations above 2.5 × 10-1 М, the solutions contain mostly the micelles, whereas at concentrations below 2.5 × 10-4 M, the solutions contain AOT molecules. The transition region contains both the AOT molecules and the micelles. Conductivity measurements were used to determine free charge carriers in the bulk of solutions and their contributions to conductivity.