Separating helium (He) and hydrogen (H2), two gases that are extremely similar in molecular size and condensation properties, presents a formidable challenge in the helium industry. The development of membranes capable of precisely differentiating between these gases is crucial for achieving large-scale, energy-efficient He/H2 separation. However, the limited selectivity of current membranes has hindered their practical application. In this study, we propose a novel approach to overcome this challenge by engineering submicroporous membranes through the fluorination of partially carbonized hollow fibers. We demonstrate that the fluorine substitution on the inner rim of the micropore walls within the carbon hollow fibers enables tunability of the microporous architecture. Furthermore, it enhances interactions between H2 molecules and the micropore walls through the polarization and hydrogen bonding induced by C-F bonds, resulting in simultaneous improvements in both He/H2 diffusivity and solubility selectivities. The fluorinated HFM-550-F-1min membrane exhibits exceptional mixed-gas separation performance, with a binary mixed-gas He/H2 selectivity of 10.5 and a ternary mixed-gas He/(H2+CO2) selectivity of 20.8, at 40 bar feed pressure and 35 oC, surpassing all previously reported polymer-based gas separation membranes, and remarkable plasticization resistance and long-term continuous stability over 30 days.
Membrane channel proteins (MCPs) play key roles in matter transport through cell membranes and act as major targets for vaccines and drugs. For emerging ionic liquid (IL) drugs, a rational understanding of how ILs affect the structure and transport function of MCP is crucial to their design. In this work, GPU-accelerated microsecond-long molecular dynamics simulations were employed to investigate the modulating mechanism of ILs on MCP. Interestingly, ILs prefer to insert into the lipid bilayer and channel of aquaporin-2 (AQP2) but adsorb on the entrance of voltage-gated sodium channels (Nav). Molecular trajectory and free energy analysis reflect that ILs have a minimal impact on the structure of MCPs but significantly influence MCP functions. It demonstrates that ILs can decrease the overall energy barrier for water through AQP2 by 1.88 kcal/mol, whereas that for Na+ through Nav is increased by 1.70 kcal/mol. Consequently, the permeation rates of water and Na+ can be enhanced and reduced by at least 1 order of magnitude, respectively. Furthermore, an abnormal IL gating mechanism was proposed by combining the hydrophobic nature of MCP and confined water/ion coordination effects. More importantly, we performed experiments to confirm the influence of ILs on AQP2 in human cells and found that treatment with ILs significantly accelerated the changes in cell volume in response to altered external osmotic pressure. Overall, these quantitative results will not only deepen the understanding of IL-cell interactions but may also shed light on the rational design of drugs and disease diagnosis.
Ionic Liquids , Molecular Dynamics Simulation , Ionic Liquids/chemistry , Ionic Liquids/pharmacology , Humans , Aquaporin 2/metabolism , Aquaporin 2/chemistry , Water/chemistry , Lipid Bilayers/chemistry , Lipid Bilayers/metabolism , Sodium/chemistry , Sodium/metabolism
Direct use of metals as battery anodes could significantly boost the energy density, but suffers from limited cycling. To make the batteries more sustainable, one strategy is mitigating the propensity for metals to form random morphology during plating through orientation regulation, e.g., hexagonal Zn platelets locked horizontally by epitaxial electrodeposition or vertically aligned through Zn/electrolyte interface modulation. Current strategies center around obtaining (002) faceted deposition due to its minimum surface energy. Here, benefiting from the capability of preparing a library of faceted monocrystalline Zn anodes and controlling the orientation of Zn platelet deposits, we challenge this conventional belief. We show that while monocrystalline (002) faceted Zn electrode with horizontal epitaxy indeed promises the highest critical current density, the (100) faceted electrode with vertically aligned deposits is the most important one in suppressing Zn metal corrosion and promising the best reversibility. Such uniqueness results from the lowest electrochemical surface area of (100) faceted electrode, which intrinsically builds upon the surface atom diffusion barrier and the orientation of the pallets. These new findings based on monocrystalline anodes advance the fundamental understanding of electrodeposition process for sustainable metal batteries and provide a paradigm to explore the processing-structure-property relationships of metal electrodes.
Harvesting electricity from widespread water evaporation provides an alternative route to cleaner power generation technology. However, current evaporation power generation (EPG) mainly depends on the dissociation process of certain functional groups (e.g., SO3H) in water, which suffers from low power density and short-term output. Herein, the Janus membrane is prepared by combining nanofluid and water-grabbing material for EPG, where the nanoconfined ionic liquids (NCILs) serve as ion sources instead of the functional groups. Benefiting from the selective and fast transport of anions in NCILs, such EPG demonstrates excellent power performance with a voltage of 0.63 V, a short-circuit current of 140 µA, and a maximum power density of 16.55 µW cm-2 while operating for at least 180 h consistently. Molecular dynamics (MD) simulation and surface potential analysis reveal the molecular mechanism, that is, the diffusion of Cl- anions during evaporation is much faster than that of cations, generating the voltage and current across the membrane. Furthermore, the device performs well in varying environmental conditions, including different water temperatures and sources of evaporating water, showcasing its adaptability and integrability. Overall, the nanofluid-guided Janus membrane can efficiently transform low-grade thermal energy in evaporation into electricity, showing a competitive advantage over other sustainable applied approaches.
The combination of high-capacitance MXenes and wide-electrochemical-window ionic liquids (ILs) has exhibited bright prospects in supercapacitors. Several strategies, such as surficial functionalization and interlayer spacing tuning, have been used to enhance the electrochemical performance of supercapacitors. However, the lack of theoretical guidance on these strategies, including the effects of the microenvironment in the interlayer of confined ILs, hindered the further exploration of such devices. Herein, we performed molecular dynamics simulations to comprehensively investigate the effects of the interlayer space and surface terminations of MXene electrodes on capacity. The results show that the electrical double layer (EDL) structure was found to form on the interface between the MXene electrode and ILs electrolyte by analyzing the ion number density and charge density in the nanometer confined spaces. Under the same potential, the -OH terminations significantly impact the ion orientation in the EDL, particularly near the electrode surface, where cations tend to align vertically, allowing the retention of more cations at the electrode surfaces. Interestingly, such an orientation distribution was decisively from the hydrogen bonds expressed by O-H···O between the -OH termination of MXene and -OH groups of ILs. The differential capacitances of the supercapacitors were calculated by the surficial electron density, and it showed that the capacitance is a nearly one-quarter increase in the 14 Å interlayer spacing compared with that of 10 Å under an applied potential of 2 V. At the same time, the Ti3C2(OH)2 electrode had a higher differential capacitance than the Ti3C2O2 electrode, which possibly originates from the stronger hydrogen bonds to contribute to the vertical aggregation of the cations. Our results highlighted the roles of the interlayer spacing distance and surface terminations of the MXene on the performance of the type of supercapacitor.
Lithium-sulfur batteries (LSBs) with superior energy density are among the most promising candidates for next-generation energy storage techniques. Sulfurized polyacrylonitrile (SPAN) exhibits competitive advantages in terms of cycle stability, rate performance as well as cost. However, the preparation of high-loading SPAN electrodes is still challenging. Herein, inspired by mussel and cobweb, a high-loading SPAN electrode is enabled by the combination of polydopamine (PDA) coating and a bimodal distributed single-wall carbon nanotubes (SWCNT) slurry dispersed in polyvinylpyrrolidone (PVP), their synergistic effect not only constructs effective electron percolating networks within the electrode but also make high active material (AM) ratio possible. High areal capacity PDA@SPAN electrode (18.40 mAh cm-2 in the initial cycle) with negligible specific capacity attenuation as the mass loading increasement is realized through the facile slurry casting process. The dynamic NâH O hydrogen bond is formed between PDA and PVP and the electrode integrity during charge/discharge is greatly strengthened. The battery with an areal AM loading of 7.16 mg cm-2 (5.16 mAh cm-2) retains 92.0% of capacity in 80 cycles and 87.18% in 160 cycles, and it also shows stable cycle performances even with a high loading of 19.79 mg cm-2 and lean electrolyte (3.28 µL mg-1).
Ionic liquids (ILs) exhibit fascinating properties due to special Z-bonds and have been widely used in electrochemical systems. The local Z-bond networks potentially cause a discrepancy in electrochemical properties. Understanding the correlations between the Z-bond energy (EZ-bond) and the electrochemical properties is helpful to identify appropriate ILs. It is difficult to estimate the correlations from single density functional theory calculations or molecular dynamic simulations. In this work, a machine learning model targeting the electronic density (ρBCP) of Z-bonds has been trained successfully, as expected for use in systems above the nanoscale size. The connection between the EZ-bond and the electrochemical potential window in ILs@TiO2, as well as that between the EZ-bond and the charge carrier mobility in ILs-PEDOT:Tos@SiO2, was separately investigated. This study highlights an efficient model for predicting ρBCP in nanoscale systems and anticipates exploring the connection between Z-bonds and the electrochemical properties of IL-based systems.
Ionic liquids (ILs), due to their inherent structural tunability, outstanding miscibility behavior, and excellent electrochemical properties, have attracted significant research attention in the biomedical field. As the application of ILs in biomedicine is a rapidly emerging field, there is still a need for systematic analyses and summaries to further advance their development. This review presents a comprehensive survey on the utilization of ILs in the biomedical field. It specifically emphasizes the diverse structures and properties of ILs with their relevance in various biomedical applications. Subsequently, we summarize the mechanisms of ILs as potential drug candidates, exploring their effects on various organisms ranging from cell membranes to organelles, proteins, and nucleic acids. Furthermore, the application of ILs as extractants and catalysts in pharmaceutical engineering is introduced. In addition, we thoroughly review and analyze the applications of ILs in disease diagnosis and delivery systems. By offering an extensive analysis of recent research, our objective is to inspire new ideas and pathways for the design of innovative biomedical technologies based on ILs.
Ionic Liquids , Ionic Liquids/chemistry , Proteins , Biomedical Technology , Cell Membrane
As spent batteries can be considered as alternative raw sources of electrode materials; the development of regeneration techniques for spent graphite becomes key to realizing economic and environmental sustainability. Herein, the reutilization of small spent graphite particles is domonstrated due to their special structural characteristics, which may directly contribute to the improvement of lithiation kinetics and high-rate charging during long-term cycling. Such intrinsic defects and external cracked channels may be introduced by the aging of intrinsic bulk structure and exfoliation of surface structure. On account of these potential advantages, a carbonized polypyrrole layer on sieved small graphite particles is developed to obtain superior rate performance. The coated amorphous/graphitic layer could repair the exposed edge and basal plane, and significantly facilitate Li ion diffusion during fast charging. Moreover, the enhanced performance may favor the improved homogeneity of current density distribution during fast charging, which is confirmed by a porous electrode model. The regenerated graphite with a disorder/order coating layer could effectively regulate the Li+ transport channel, exhibiting a high specific capacity at high-rate charging (102.7 mAh g-1 at 4 C after 500 cycles) without severe Li plating. This work provides an opportunity to utilize spent graphite in fast-charging batteries.
This perspective depicts a green hydrogen and green electricity-driven low-carbon future for chemical industry, which requires revolutionary technologies from feedstock replacements, catalyst and reactor innovations to integrated intelligent systems.
Electrochemical conversion of nitrate to ammonia is an appealing way for small-scale and decentralized ammonia synthesis and waste nitrate treatment. Currently, strategies to enhance the reaction performance through elaborate catalyst design have been well developed, but it is still of challenge to realize the promotion of reactivity and selectivity at the same time. Instead, a facile method of catalyst modification with ionic liquid to modulate the electrode surface microenvironment that mimic the role of the natural MoFe protein environment is found effective for the simultaneous improvement of NH3 yield rate and Faradaic efficiency (FE) at a low NaNO3 concentration of 500â ppm. Protic ionic liquid (PIL) N-butylimidazolium bis(trifluoromethylsulfonyl)imide ([Bim]NTf2 ) modified Co3 O4-x is fabricated and affords the NH3 yield rate and FE of 30.23±4.97â mg h-1 mgcat. -1 and 84.74±3.43 % at -1.71 and -1.41â V vs. Ag/AgCl, respectively, outperforming the pristine Co3 O4-x . Mechanistic and theoretical studies reveal that the PIL modification facilitates the adsorption and activation of NO3 - as well as the NO3 - -to-NH3 conversion and inhibits hydrogen evolution reaction competition via enhancing the Lewis acidity of the Co center, shuttling protons, and constructing a hydrogen bonded and hydrophobic electrode surface microenvironment.
Covalent organic frameworks (COFs) hold the potential in converting CO2 with water into value-added fuels and O2 to save the deteriorating ecological environment. However, reaching high yield and selectivity is a grand challenge under metal-, photosensitizer-, or sacrificial reagent-free conditions. Here, inspired by microstructures of natural leaves, we designed triazine-based COF membranes with the integration of steady light-harvesting sites, efficient catalytic center, and fast charge/mass transfer configuration to fabricate a novel artificial leaf for the first time. Significantly, a record high CO yield of 1240 µmol g-1 in a 4 h reaction, approximately 100% selectivity, and a long lifespan (at least 16 cycles) were achieved under gas-solid conditions without using any metal, photosensitizer, or sacrificial reagent. Unlike the existing knowledge, the chemical structural unit of triazine-imide-triazine and the unique physical form of the COF membrane are predominant for such a remarkable photocatalysis. This work opens a new pathway to simulating photosynthesis in leaves and may motivate relevant research in the future.
Molecular dynamic simulations of aqueous mixtures of imidazolium ionic liquids (ILs) were performed to elucidate the dependence of the ionic diffusivity on the microscopic structures changed by water. Two distinct regimes of the average ionic diffusivity (Dave) were identified with the increased water concentrations: the jam regime with slowly increased Dave and the exponential regime with rapidly increased Dave, which are found to be directly correlated to the ionic association. Further analysis leads to two general relationships independent of IL species between Dave and the degree of ionic association: (i) a consistent linear relationship between Dave and the inverse of ion-pair lifetimes (1/τIP) in the two regimes and (ii) an exponential relationship between normalized diffusivities (DÌave) and short-ranged interactions between cations and anions (Eions), with different interdependent strengths in the two regimes. These findings revealed and quantified the direct correlation between dynamic properties and ionic association in IL-water mixtures.
Activation and turning CO2 into value added products is a promising orientation to address environmental issues caused by CO2 emission. Currently, electrocatalysis has a potent well-established role for CO2 reduction with fast electron transfer rate; but it is challenged by the poor selectivity and low faradic efficiency. On the other side, biocatalysis, including enzymes and microbes, has been also employed for CO2 conversion to target Cn products with remarkably high selectivity; however, low solubility of CO2 in the liquid reaction phase seriously affects the catalytic efficiency. Therefore, a new synergistic role in bioelectrocatalysis for CO2 reduction is emerging thanks to its outstanding selectivity, high faradic efficiency, and desirable valuable Cn products under mild condition that are surveyed in this review. Herein, we comprehensively discuss the results already obtained for the integration craft of enzymatic-electrocatalysis and microbial-electrocatalysis technologies. In addition, the intrinsic nature of the combination is highly dependent on the electron transfer. Thus, both direct electron transfer and mediated electron transfer routes are modeled and concluded. We also explore the biocompatibility and synergistic effects of electrode materials, which emerge in combination with tuned enzymes and microbes to improve catalytic performance. The system by integrating solar energy driven photo-electrochemical technics with bio-catalysis is further discussed. We finally highlight the significant findings and perspectives that have provided strong foundations for the remarkable development of green and sustainable bioelectrocatalysis for CO2 reduction, and that offer a blueprint for Cn valuable products originate from CO2 under efficient and mild conditions.
Carbon Dioxide , Electrochemical Techniques , Electron Transport , Biocatalysis , Catalysis
Toluene is a prevalent pollutant in indoor environments and its removal is essential to maintain a healthy environment. Adsorption is one of the best alternatives for organic vapours removal, specially at low indoor concentrations. Metal Organic Frameworks (MOFs) and Ionic Liquids (ILs) are potential materials for this mean. In this work, the synthesis and application of IL/MOF composite materials for toluene removal is reported. Loading [BMIM][CH3COO] ionic liquid into MIL101 porous structure improves parent materials affinity towards toluene capture by two orders of magnitude (as Henry's constants, attesting to their synergy). MIL101(Cr) and absorption in [BMIM][CH3COO] IL is best described by Henry's Law, while the Langmuir adsorption model predicts toluene adsorption on [BMIM][CH3COO]/MIL101(Cr) better than Freundlich and Toth equations. Diffusional and kinetics models revealed that toluene diffusion is the rate limiting step for pristine MIL101. Kinetic and diffusion rates were systematically improved upon the incorporation of the ionic liquid due to shorter toluene hops with the adsorbed IL and the increased hydrophobicity in the composites making the sorption more favourable. This study provides a systematic analysis and modelling of the toluene capture process in IL/MOF composites aiding a better understanding of the sorption process in these novel materials.
Environmental Pollutants , Ionic Liquids , Metal-Organic Frameworks , Toluene/chemistry , Ionic Liquids/chemistry , Gases
Li+ solvation structures have a decisive influence on the electrode/electrolyte interfacial properties and battery performances. Reduced salt concentration may result in an organic rich solid electrolyte interface (SEI) and catastrophic cycle stability, which makes low concentration electrolytes (LCEs) rather challenging. Solvents with low solvating power bring in new chances to LCEs due to the weak salt-solvent interactions. Herein, an LCE with only 0.25 mol L-1 salt is prepared with fluoroethylene carbonate (FEC) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether (D2). Molecular dynamics simulations and experiments prove that the low solvating power solvent FEC not only renders reduced desolvation energy to Li+ and improves the battery kinetics, but also promotes the formation of a LiF-rich SEI that hinders the electrolyte consumption. Li||Cu cell using the LCE shows a high coulombic efficiency of 99.20%, and LiNi0.6Co0.2Mn0.2O2||Li cell also exhibits satisfying capacity retention of 89.93% in 200 cycles, which demonstrates the great potential of solvating power regulation in LCEs development.
Ultralow friction between interacting surfaces in relative motion is of vital importance in many pure and applied sciences. We found that surfaces bearing ordered monolayer ionic liquids (ILs) can have friction coefficient µ values as low as 0.001 at pressures up to 78 MPa and exhibit good structure recoverability. This extreme lubrication is attributed primarily to the ordered striped structure driven by the "atomic-locking" effect between carbon atoms on the alkyl chain of ILs and graphite. The longer alkyl chain has lower µ values, and the stripe periodicity is decisive in reducing energy dissipation during the sliding process. In combination with simulation, the alternate atomic-scale ordered and disordered ionic regions were recognized, whose ratio fundamentally determines the µ values and lubrication mechanism. This finding is an important step toward the practical utilization of ILs with negligible vapor pressure as superlubricating materials in future technological applications operating under extreme conditions.
The commercialization of lithium-sulfur batteries with ultra-high theoretical energy density is restricted mainly by the notorious polysulfides "shuttle effect" and slow Li2 S redox reaction kinetics. A sulfur host material with high catalytic activity and high conductivity is greatly desired to improve its electrochemical performance. Herein, a sulfur host material, etched cotton@petroleum asphalt carbon (eCPAC), with high specific surface area and excellent catalytic activity, is demonstrated based on a synergistic strategy of introducing intrinsic lattice defects and composite carbon structure. Benefiting from in situ coupling of amorphous and crystalline materials, eCPAC exhibits high conductivity and high sulfur adsorbability. Furthermore, eCPAC containing dual intrinsic defect sites can catalyze the bidirectional sulfur chemistry of Li2 S and capture polysulfides, which is also demonstrated by systematic density functional theory calculations and the potential intermittent titration technique. S@eCPAC/Li cells exhibit excellent cycling stability and rate performance, with an average capacity decay rate of only 0.05% over 1000 cycles at 0.5 C and even 0.03% over 600 cycles at 5 C. Meanwhile, the practicality of eCPAC is proven in high-load batteries and pouch batteries. eCPAC provides a reliable strategy for achieving a win-win situation of capturing polysulfides and accelerating Li2 S redox kinetics.
SiOx suspension is regarded as an attractive anolyte for high-energy-density Li-ion slurry flow batteries. However, the poor electronic conductivity and non-negligible volume variation of SiOx greatly hinder its practical applications. Herein, these issues are successfully addressed by rationally designing a trifunctional interface with mixed electron/ion and hard/soft modulated properties on SiOx surface via H-bonding interactions. The interface comprises a lithiated polymer layer (LiPN) interfused with functionalized single-walled carbon nanotubes. Carbon nanotubes work as electrical tentacles to enhance the multiscale electron conduction. The LiPN layer with transferable Li-ions facilitates ion transport. In addition, the LiPN layer employs lithiated rigid polyacrylic acid as a framework to provide mechanical support and soft nafion as a buffer to accommodate volume change, which maintains the structural integrity of SiOx . Hence, SiOx @LiPN/S anolytes exhibit significantly improved rate and cycle performances. Specially, the interface enables the anolytes to load more active particles (30 wt%) or less conductive additives (0.4 wt%). The semi-solid pouch cells based on high-active-content anolytes with stable cyclability are first demonstrated and the flow cell using low-conductive-content anolytes displays a high volumetric capacity of 207 Ah L-1 . This strategy paves a novel approach for optimizing semi-solid electrodes for high-performance Li-ion slurry flow batteries.
Ionic liquids (ILs) hold great promise in the fields of green chemistry, environmental science, and sustainable technology due to their unique properties, such as a tailorable structure, the various types available, and their environmentally friendly features. On the basis of multiscale simulations and experimental characterizations, two unique features of ILs are as follows: (1) strong coupling interactions between the electrostatic forces and hydrogen bonds, namely in the Z-bond, and (2) the unique semiordered structure and properties of ultrathin films, specifically regarding the quasi-liquid. In accordance with the aforementioned theoretical findings, many cutting-edge applications have been proposed: for example, CO2 capture and conversion, biomass conversion and utilization, and energy storage materials. Although substantial progress has been made recently in the field of ILs, considerable challenges remain in understanding the nature of and devising applications for ILs, especially in terms of e.g. in situ/real-time observation and highly precise multiscale simulations of the Z-bond and quasi-liquid. In this Perspective, we review recent developments and challenges for the IL research community and provide insights into the nature and function of ILs, which will facilitate future applications.
