Search

Characterizing atom/ion mobility in superionic materials is one of the most essential topics. In this work, we show that the copper ion mobility in a promising thermoelectric material Cu x AgSe y (x, y = 0.98, 1.02), can be significantly changed by modulating the element ratio, x/y. With 63 Cu NMR linewidth as a direct measure of the copper ion mobility, we observed distinguishable Cu ion mobility in the samples with different ratios even under ambient temperatures. This distinction was further evaluated in terms of correlation times and activation energy of copper diffusion. The contrast in ion mobility could be understood from the point of view of vacancy mediation. This work gives fruitful information for understanding ion dynamics and related topics.

A green and efficient liquid–liquid extraction system was developed for the separation of lithium isotopes by using hydrophobic ionic liquids (ILs = [C4,6,8,10mim]+[NTf2]−) as extraction organic phase and benzo-15-crown-5 (B15C5) as complexing agent. The maximum single-stage separation factor α of 6Li/7Li obtained in this study was 1.029 ± 0.001, indicating 6Li was enriched in ionic liquid phase while 7Li was concentrated in the aqueous phase. The lithium ion was extracted into the ionic liquid in the formation of 1:2 complex [Li+(B15C5)2]. The negative data of thermodynamic parameters (∆ H0 and ∆ G0) suggest that the extraction system was a spontaneous exothermic process. In addition, effective lithium isotopes separation factor and the extraction efficiency of lithium ions can be gained in the condition of lower temperature with softer counter anions in the novel extraction system.

A novel phosphonium ionic liquid (IL), tetrabutylphosphonium bis(2,4,4-trimethylpentyl)phosphinate([P 4444 ][BTMPP]), was prepared and characterized by NMR spectroscopy. The solvent extraction behavior of lithium from aqueous solution by this IL in toluene was investigated. The extraction behavior was carried out as a function of various parameters such as aqueous acidity, temperature and extractant concentration. The extraction efficiencies obtained in [P 4444 ][BTMPP] were compared with those observed in molecular extractant bis(2,4,4-trimethylpentyl) phosphinic acid (HBTMPP), from which the anion of the ionic liquid extractant was prepared. The extraction efficiency for extraction of lithium by [P 4444 ][BTMPP] was much higher than that for extraction by HBTMPP. The extracted species were ascertained from slop analysis method which indicated 1:1 (metal:ligand) ratio in the complex. In addition, the effects of thermodynamic parameters, the stripping of lithium from the ionic liquid, and the reusability of the phosphonium ionic liquid were studied in detail.

Extraction of Li+ ions from salt lake brine into an ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) mixed with tri-n-butyl was investigated. The extraction mechanism was been studied using UV–Vis spectroscopy From the temperature dependence data, the thermodynamic functions values (ΔG°, ΔH°, and ΔS°) were calculated. Furthermore, stripping of metals from ionic liquid phase to an aqueous phase by hydrochloric acid was accomplished.

Atomic-scale dynamics of a representative noble metal chalcogenide superionic conductor, stromeyerite (CuAgS), were examined by nuclear magnetic resonance (NMR) spectroscopy at various temperatures. Motional narrowing of 63 Cu NMR line width was found in its cubic phase, demonstrating copper ions start diffusing via a hopping process. Moreover, the absence of 63 Cu NMR signal in its orthorhombic or hexagonal phases was discussed, which could be well explained by copper ordering and reduced local symmetry at copper sites. The above NMR results are relevant for understanding its electron-crystal phonon-liquid behaviors and transient structure-transformation, which are associated with extremely low thermal conductivities and abnormal change of thermal power during superionic phase transition in this material.

Two non-fluorinated ionic liquids (ILs), namely tetrabutylammonium bis(2-ethylhexyl)-phosphate, [N4444][DEHP], and tetraoctylammonium bis(2-ethylhexyl)-phosphate, [N8888][DEHP], were synthesized and fully characterized by 1H and 13C NMR spectroscopy. These functionalized ILs were subsequently evaluated in terms of their ability to extract lithium ions from aqueous solution. The extraction efficiencies of these functionalized ILs for lithium ions were measured as a function of various extraction parameters, including aqueous acidity, temperature and extractant concentration. The extracted species were determined using a slope analysis method, which indicated that the ILs formed a 1:1 (metal:ligand) complex. Fourier transform infrared spectroscopy studies were conducted to better understand the nature of the extracted species. We also investigated the stripping of the lithium ions from the organic phase and the re-use of the ionic liquid in a subsequent extraction step.

In this paper, a novel liquid-liquid extraction system was investigated for the selective separation of lithium isotopes using ionic liquid (IL) and dichloroethane as extraction solvent and dibenzo-14-crown-4 (DB14C4) as extractant. Results showed that the separation performance of DB14C4 has been improved after the ILs were involved in the extraction process. The maximum single stage separation factor α for 6Li/7Li obtained in the present study was 1.021. The light lithium isotope 6Li and the heavy lithium isotope 7Li were concentrated in organic phase and solution phase, respectively. The order of the single stage separation factor obtained in different lithium salts was LiI > LiBr > LiClO4 > LiCl. From the temperature dependence data, the thermodynamic functions values of the lithium isotope exchange reaction were calculated.

A novel liquid–liquid extraction system was investigated for the selective separation of lithium isotopes using ionic liquids (ILs = [C 6,8,10,12 mim] + [PF 6 ] － ) as extraction solvent and benzo-15-crown-5 (B15C5) as extractant. The effects of the concentration of lithium salt, counter anion of lithium salt, initial pH of aqueous phase, and extraction temperature on the lithium isotopes separation were studied. The maximum single-stage separation factor α of 6 Li/ 7 Li obtained in the present study was 1.038 ± 0.002, indicating the lighter isotope 6 Li was enriched in organic phase while the heavier isotope 7 Li was concentrated in the aqueous phase. The formation of 2:1 complex Li(B15C5) 2 + in the IL phase was determined on the basis of slope analysis method. The large value of the free energy change (− G 0 = 77.87 J mol −1 ) indicated the high separation capability of the lithium isotopes by B15C5/30%CH 3 Cl-70% C 6 mimPF 6 mixture extraction system. Lithium in Li(B15C5) 2 + complex was stripped by 0.5 mol·L −1 HCl solution. The extraction system offers high efficiency, simplicity application prospect to separation lithium isotope separation from LiCl solution.

The key progress in the development of solar cells based on mixed organic-inorganic halide perovskite was reviewed. Perovskite solar cells (PSCs) have developed rapidly and achieved highest efficiency exceeding 20% in these years. The origin, working principle and fabrication technology of PSCs are stated, and several promising methods to realize the industrialization of the solar cell modules have been put forward. Meanwhile, two main problems existing in PSCs have been pointed out, hysteresis in the photocurrent density-voltage measurement and the instability of perovskite, which have impacted the application of PSCs seriously. Efforts and study in order to solve these problems are also listed. The fundamental mechanism still needs further investigation so as to improve the performance of PSCs and realize their large-scale application eventually.

Herein, the amine-functionalized MCM-41 mesoporous silica (denoted as MCM-41-NH2) was synthesized and applied to adsorption and recovery U(VI) ions from aqueous solutions. The results showed that the sorption of U(VI) on MCM-41-NH2 was strongly dependent on pH and ionic strength. The sorption was mainly dominated by outer-sphere surface complexation and the sorption equilibrium can be reached within 60 min. The maximum sorption capacity of MCM-41-NH2 for U(VI) was calculated to be 386.98 mg g−1 at pH 5.60, much higher than that of the other reported materials.

Separation among lithium ion and magnesium ion remains challenging. In this work, solvent extraction of lithium ions from the Mg(II)-containing salt lake brine into a commonly used ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([C 4 mim][NTf 2 ]) using the neutral phosphorus compound tri-n-butyl phosphate (TBP) as the extractant was investigated. The extraction behavior of lithium ions was investigated as a function of various parameters: acidity of the salt lake brine, dosage of ionic liquid and phase ratio. Under the optimal conditions, the single extraction efficiency of lithium was 92.37%, which indicated that it was an efficient extraction system for the recovery of lithium ions. Based on the study of thermodynamics, thermodynamic parameters of the lithium ion extraction reaction were obtained. The extracted species were ascertained from slope analysis method which indicated 1:1 (metal:ligand) ratio in the complex. UV–visible and Fourier transform infrared spectroscopy (FTIR) studies were also carried out to understand the nature of the extracted species.

Water molecules have been reported to cause the degradation of perovskite crystals by forming a hydrated intermediate structure and then lead iodide irreversibly. Here, the quality of fully crystallized perovskite films is found to be improved by spraying water vapor with an appropriate time. Moreover, this healing effect was found to be reversible and would disappear when the water molecules escaped. Through measuring the steady-state and time-resolved photoluminescence of perovskite film before and after water vapor spray, we found that water molecules can deactivate the nonradiative recombination centers due to hydrogen bonding with uncoordinated ions on the surface of perovskite film. Furthermore, by analyzing the capacitance of devices without and with water vapor spray, the healing or deactivation effect was clearly seen in the significantly decreased density of defect states. This work emphasized the effectiveness of hydroxyl to heal the defects due to dangling bonds on the material surface, and cl...

To examine the ionic migrations on atomic level in metal chalcogenide phonon glasses, 63Cu solid state nuclear magnetic resonance (NMR) spectroscopy was performed in an archetype CuAgSe compound. The observed characteristic motional narrowing effect in the superionic state provide clear evidence for the model of single ion-hopping instead of free-ion-like motion. We further find, for the first time, that thermal conductivity is strongly correlated with cation dynamics revealed by NMR within the range of temperatures investigated. This investigation provides better understanding how microscopic structure affects thermal transport properties which is of current interest in transition-metal chalcogenide based fast ion conductors.