Separation Of Materials Research Articles

Effects of template molecules on the molecular permeability of molecularly imprinted polysaccharide composite films

Abstract pH-responsive materials comprising natural polysaccharides have attracted attention due to their high biocompatibility and biodegradability, and are potentially useful as biomaterials. In particular, polysaccharide film materials can be used as drug carriers, wound dressings, and separation materials. We have succeeded in the fabrication of polysaccharide composite films from polyion complexes of anionic polysaccharides and chitosan. These films showed molecular permeability and the permeation behavior can be controlled by applying a molecular imprinting approach while using a cationic molecule as the template. However, the details of the effects of template molecules have not been clarified. In this study, to investigate the effects of the characteristics of the template molecules on the molecular permeability of the film, molecularly imprinted polysaccharide composite films were prepared by using template molecules with different sizes and charge valences. The molecular permeation behaviors of the resulting films were then evaluated under different pH conditions. It was found that differences in template molecules affected the swelling ratio and surface charge of the films. Moreover, the permeation behavior was largely affected by the surface charge of the film, while the size of the template molecule had little effect. Based on the results, the mechanism for the molecular permeation is discussed. These results will contribute to the application of polysaccharide composite films as pH-responsive materials.

Manganese-Coordinated Cellulose Based-Separator for Efficient and Reliable Zn-Ion Transport

Aqueous zinc-ion batteries (AZIBs) are increasingly being acknowledged as a promising candidate to safely power large-scale energy storage systems and portable devices. However, the development of effective separator materials remains a significant challenge due to issues such as harmful dendrite growth on zinc (Zn) anodes and parasitic side reactions in aqueous electrolytes. To address this challenge, we synthesize a manganese-coordinated cellulose nanofibril (Mn-CNF)-based separator for high-performance AZIBs. This separator affords enhanced ion transport channel, a large number of hydroxyl groups, and exceptional mechanical properties, with a tensile strength of 2.8 MPa and superior ionic conductivity of 5.14 mS·cm−1. These attributes collectively enhance Zn-ion transport, minimize nucleation overpotential for Zn, and accelerate the Zn deposition kinetics, thus significantly outperforming the untreated CNF separators. Consequently, the Zn||MnO2 battery with the Mn-CNF separator shows a marked improvement in the galvanostatic rate performance and cycling stability by effectively accelerating and optimizing Zn-ion transport. This study offers valuable insights into the development of efficient and reliable separators for advanced electrochemical energy storage technologies.

Improved superhydrophobicity of magnetic melamine sponge by aminosilane for batch and continuous oil–water separation

Continuous and efficient separation remains the thorny problem that restricts oil–water separation materials for the large-scale application of oil–water separation. A kind of magnetic melamine sponges with enhanced superhydrophobicity was fabricated by dip coating of polydopamine-modified Fe3O4 nanoparticles, (3-aminopropyl)triethoxysilane (APTES) and hexadecyltrimethoxysilane (HDTMS) on melamine sponge. The superhydrophobicity of melamine sponge was improved by adding APTES to cover hydrophilic group of polydopamine. The melamine sponge exhibited water contact angle of 158.3°, the absorption capacity of 43.2–80.7 g/g, volume utilization of 0.70–0.97 v/v and separation efficiencies of 99.6 % for oil–water mixture and 98.6 % for oil/water emulsion. The sponge could carried out in batch and continuous filter devices, and repeated oil absorption capacity could achieve 92.8–96.4 % of initial oil absorption capacity after 45 absorbing-squeezing cycles. The above performances of the as-prepared sponge suggest that it is a promising candidate for large-scale application of oil-spill cleanup and oily wastewater treatment.

Macromolecular Architecture in the Synthesis of Micro- and Mesoporous Polymers.

Polymers with micro- and mesoporous structure are promising as materials for gas storage and separation, encapsulating agents for controlled drug release, carriers for catalysts and sensors, precursors of nanostructured carbon materials, carriers for biomolecular immobilization and cellular scaffolds, as materials with a low dielectric constant, filtering/separating membranes, proton exchange membranes, templates for replicating structures, and as electrode materials for energy storage. Sol-gel technologies, track etching, and template synthesis are used for their production, including in micelles of surfactants and microemulsions and sublimation drying. The listed methods make it possible to obtain pores with variable shapes and sizes of 5-50 nm and achieve a narrow pore size distribution. However, all these methods are technologically multi-stage and require the use of consumables. This paper presents a review of the use of macromolecular architecture in the synthesis of micro- and mesoporous polymers with extremely high surface area and hierarchical porous polymers. The synthesis of porous polymer frameworks with individual functional capabilities, the required chemical structure, and pore surface sizes is based on the unique possibilities of developing the architecture of the polymer matrix.

In situ construction of 3D 1T-VS2/V2C heterostructures for enhanced polysulfide trapping and catalytic conversion in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries represent a promising next-generation energy storage solution, yet their performance is hindered by the insulating nature of sulfur and the detrimental shuttle effect. This study presents the in-situ synthesis of metal-phase 1T-VS2 as a modified separator material on a two-dimensional Mxene substrate V2C (VSC). The synergistic effect of strong adsorption by V2C and highly conductive catalysis provided by 1T-VS2 significantly enhances the transport of ions and electrons between lithium polysulfide and the interface. The combinations of experimental data and density functional theory (DFT) indicate that 1T-VS2, which is characterized by its high density of defective active sites and high conductivity, not only effectively improves the adsorption of lithium polysulfides, but also dramatically lowers the redox energy barrier of Li2S, thereby accelerating the chemical reaction kinetics. As a result, the Li-S cells assembled by the VSC-modified separator exhibit an impressive initial capacity of 1131 mAh/g at 1 C with a capacity decay rate of only 0.05% per cycle. In addition, even after 100 cycles and at a high sulfur loading of 5.6 mg cm−2, the cells maintain a discharge capacity of 817 mAh/g. Impressively, the VSC continues to deliver excellent cycling and rate performance even when the environmental temperature is reduced to 0 °C. These findings offer valuable insights into the potential for the advancement of highly practical Li-S batteries.

Degradation Mechanism of Phosphate-Based Li-Nasicon Conductors in Alkaline Environment

Li-NASICON solid-state superionic conductors have traditionally been regarded as promising candidates for Li-air applications because of their stability in ambient air and water [1], [2]. However, the presence of water in the cathode can change the discharge product from Li2O2 to LiOH [3], [4], inducing a highly alkaline environment which may degrade cathode and separator materials. Here, we investigate the impact of octahedral substitution on the alkaline stability of common Li-NASICON chemistries through a systematic experimental case study of LiTixGe2-x(PO4)3 (LTGP) with varying x = 0 - 2.0. Density functional theory calculations are combined to gain mechanistic understandings of the alkaline instability. We demonstrated that the alkaline instability of LTGP is mainly driven by the dissolution of PO4 polyanion groups, which subsequently precipitate as Li3PO4. The introduction of Ti facilitates the formation of a Ti-rich compound on the surface that eventually passivates the material, but only after significant bulk degradation. Consequently, phosphate-based Li-NASICON materials exhibit limited alkaline stability, raising concerns of their viability in humid Li-air batteries.[1] N. Imanishi, S. Hasegawa, T. Zhang, A. Hirano, Y. Takeda, and O. Yamamoto, “Lithium anode for lithium-air secondary batteries,” Journal of Power Sources, vol. 185, no. 2, pp. 1392–1397, Dec. 2008, doi: 10.1016/j.jpowsour.2008.07.080.[2] R. Chen, Q. Li, X. Yu, L. Chen, and H. Li, “Approaching Practically Accessible Solid-State Batteries: Stability Issues Related to Solid Electrolytes and Interfaces,” Chem. Rev., vol. 120, no. 14, pp. 6820–6877, Jul. 2020, doi: 10.1021/acs.chemrev.9b00268.[3] S. Ma, J. Wang, J. Huang, Z. Zhou, and Z. Peng, “Unveiling the Complex Effects of H2O on Discharge–Recharge Behaviors of Aprotic Lithium–O2 Batteries,” J. Phys. Chem. Lett., vol. 9, no. 12, pp. 3333–3339, Jun. 2018, doi: 10.1021/acs.jpclett.8b01333.[4] T. Liu et al., “Cycling Li-O2 batteries via LiOH formation and decomposition,” Science, vol. 350, no. 6260, pp. 530–533, Oct. 2015, doi: 10.1126/science.aac7730.

Solidification of High-Concentration Electrolytes with Faujasite As Nanosized Porous Zeolite Additive for Solid-Type Batteries

Introduction: With a renewed push for commercialization of Li-metal anode batteries due to their potential to drastically increase battery performance, new electrolyte systems need to be investigated that can not only withstand the harsh reduction potential of Lithium, but also be used with cathodes operating above 4 V. Commercially used electrolytes such as ethylene carbonate (EC) and dimethyl carbonate (DMC), with lithium-salt concentrations in the range of 1 M exhibit high ionic conductivities, however, are susceptible to leakage, show high volatility which together with the high flammability of organic electrolyte solutions, lead to safety concerns and show incompatibilities with Li-metal anodes.[1][2][3] High-concentration liquid electrolytes (HCLE) due to their stability against Li-metal anodes and their wide electrochemical stability window are viewed as promising alternatives.[4][5] However, commercially used separators made from polypropylene (PP) suffer from low wettability with high-concentration electrolytes[6] and are susceptible to thermal shrinking leading to fatal malfunctioning of the cell.[7] Therefore, there is an interest in finding new separator materials with excellent wettability that can utilize the unique properties of high-concentration electrolytes while simultaneously increasing its performance by enhancing its safety properties.In this report we propose the use of nanosized lithiated faujasite-type zeolite (FAUX-Li) powder as solidification agent of HCLE made from DMC and LiFSI for the preparation of a quasi-solid-state electrolyte (QSSE) in lithium metal batteries. QSSE, electrolytes which consist of a solid-matrix for stability improvement and a liquid electrolyte for facilitating the ion-transport, with the potential to improve the safety by leakage prevention. Experimental: HCLE was prepared by mixing lithium bis(fluorosulfonyl)imide (LiFSI, IONEL®, Nippon Shokubai Ltd.) with dimethyl carbonate (DMC, >99.5 %, Kishida Chemicals Ltd.) in a molar ratio of LiFSI:DMC= 1/1.5. For the preparation of the quasi-solid-state electrolyte (QSSE), lithiated faujasite (FAUX-Li, Nakamura-choukou Ltd., Si/Al = 1.15, average particle size of 100 nm) was mixed into the HCLE in a weight ratio of 1:3 and mixed hereafter via a shaker until the mixture showed a smooth texture. Low-concentration liquid electrolyte (LCLE) with 1 M LiFSI in DMC solution was also made. Electrochemical stability was investigated by CV and LSV with Cu||Li and Li||Al cells respectively. Stability of the electrolyte with Lithium metal was performed with Li||Li cells. Li-surface morphology was analyzed with SEM. Performance of electrolyte was investigated in LFP||Li 2023-type coin cells with HCLE, QSSE and LCLE. LFP dry electrodes with 70% LFP, 25 wt% AB and 5% PTFE with an active material load of 1.5 mAh cm-2 were used. TG-DTA was used for thermal analysis of the electrolyte and FT-IR for the electrolyte solvation structure analysis. Results: Mixing of HCLE with the FAUX-Li resulted in the formation of a QSSE that displayed excellent wettability with a wide electrochemical stability window up to 5.25 V vs Li/Li+ and good stability with the Li-metal anode, analyzed by LSV and CV respectively. Li-metal compatibility was further investigated by employing the QSSE in a symmetrical Li||Li cell, cycled at 25 °C with a current density of 0.1 mA cm-2. While the QSSE was able to cycle stable for 500 cycles with no signs of dendrite formation, shown by SEM analysis, the HCLE showed instable cycling after 90 cycles and an irregular Li-metal surface. Stable cycling of the QSSE can be explained by the increase of LiTN to 0.68 from 0.49 for the HCLE. The increase of LiTN is due to the interaction of the FSI-anion with the Lewis-acidic functional group of the FAUX-Li hindering its movement when a potential is applied. LFP||Li cells with HCLE, QSSE and low-concentration electrolyte (1 M LiFSI in DMC, LCLE) were tested to compare the performance. Compared to the HCLE and LCLE, the QSSE showed a good initial capacity of 151 mAh g-1, negligible capacity loss after 100 cycles with a capacity retention of 98.6 % and excellent coulombic efficiency. This report shows that the QSSE has good stability and excellent properties when used in a lithium-metal battery.[1] C. Cao, Y. Zhong, Z. Shao, Chin. J. Chem. 2023, 41, 1119–1141.[2] X. Wu, K. Song, X. Zhang, N. Hu, L. Li, W. Li, L. Zhang, H. Zhang, Front. Energy Res. 2019, 7.[3] X. Yu, R. Chen, L. Gan, H. Li, L. Chen, Engineering 2023, 21, 9–14.[4] G. A. Giffin, Nat. Commun. 2022, 13, 5250.[5] J. Wang, Y. Yamada, K. Sodeyama, C. H. Chiang, Y. Tateyama, A. Yamada, Nat. Commun. 2016, 7, 12032.[6] Y. Yamada, Bull. Chem. Soc. Jpn. 2020, 93, 109–118.[7] L. Zhao, Y. Li, M. Yu, Y. Peng, F. Ran, Advanced Science 2023, 10,202300283. Figure 1

Ingenious design of novel layered double hydroxide/conjugated microporous polymer modified silica gel for diversified chromatographic applications

The development of novel stationary phases with specific functionalities for multitudinous separations has far-reaching implications in the field of chromatography. Layered double hydroxide (LDH) shows great potential for application in separation science, and the composite use of LDH with other materials is an effective way to increase its application potential. Herein, an attempt has been made for the first time to combine LDH nanosheets with full exposure of active sites and porous conjugated microporous polymer (CMP) with π-conjugated backbones and large aperture cavity for the preparation of a novel separation material. Compositing of 2D-LDH nanosheets with CMP can achieve synergistic effects, coupling the coordination, hydrogen bonding and electrostatic interactions provided by LDH with the hydrophobic and π-conjugation properties of CMP, which is expected to enhance the separation capabilities. In this work, 2D-LDH/CMP@SiO2 composites were first developed as liquid chromatographic stationary phases, in which CMP was coordinated with metal ions on LDH nanosheets, and meanwhile, immobilized on the thiolated silica microspheres via thiol-yne click reaction. This facile strategy not only reduces the particle aggregation of LDH, but also increases its opportunity to interact with analytes, thus endowing the composites with more interaction sites. The synthesized novel 2D-LDH/CMP@SiO2 possesses superior separation efficiency and selectivity to the CMP@SiO2 and commercialized columns, which shows good separation for various hydrophilic/ionic/hydrophobic analytes, including polycyclic aromatic hydrocarbons, steroid hormones, bisphenols, phthalates, alkylphenols and positional isomers. The separation process is determined by multiple interactions resulting from the synergistic function of CMP and 2D-LDH materials. In summary, this work confirms the promising application of 2D-LDH/CMP@SiO2 composites in the separation of multicomponent samples, providing new possibilities for the use of LDH/CMP as functional materials for liquid chromatographic separation.

New Insights into the Effect of Cellulose-Based Separators on Electrode-Electrolyte Interface in Lithium Metal Batteries

With a surging demand for electrification, lithium-ion batteries (LIBs) featuring higher energy and power densities have become indispensable. Copious research is being conducted on various components of LIBs to achieve cells with superior performance. Among these components, the separator plays a crucial role as it serves as insulation between the positive and negative electrodes while providing mechanical and thermal stability to the cells, thereby ensuring battery safety. In the pursuit of enhancing separators, a sufficient and controllable porosity and increased electrolyte wettability have gained prominence in separator research for high-performance LIBs, reflected in a large increase in research publications on separator technology in the past decade1.Currently, polyethylene (PE)/polypropylene (PP) membranes, known for their desirable electrochemical stability, have been the favored material for separators. However, these membranes have poor thermal stability, particularly at higher temperatures associated with fast charging rates. This thermal vulnerability can culminate in the decomposition of the separator, introducing a major hazard in the form of electrical shorts that may discharge the battery and lead to battery fires. Thus, separator materials that offer superior safety benefits are needed to ensure safe application of LIBs in next-generation applications2.Among the proposed materials for next-generation separators, there is a notably strong interest in cellulose-based separators (CBS). The primary advantage of cellulose compared to PE/PP membranes is greater thermal stability, as demonstrated by an initial decomposition temperature of 270°C. This greatly increases the safety of the battery since the risk of battery fires stemming from separator decomposition is reduced significantly. Along with increased thermal stability, several reports have shown enhanced energy density, and longevity in LIBs using CBS because of its desirable electrochemical stability, wettability, and water scavenging capability3,4,5.In this work, we study the CBS in a Li-metal battery with inherently higher energy density, thus, intensified challenges. While the majority of reports discuss the advantages of CBS, herein, we present new insights into possible drawbacks of CBS and its suitability for highly concentrated Li-based batteries. We investigated a commercial CBS with Li metal anode and NMC cathode materials. The compatibility and performance of CBS in Li metal-based coin cells (symmetrical and asymmetrical) are studied through electrochemical measurement techniques including cyclic voltammetry (CV), pre- and post-cycling electrochemical impedance spectroscopy (EIS) and cycling test. Similar measurements are carried out on cells with conventional PE/PP separator. Surface and morphological characterizations are conducted on the CBS, Li metal anode, and cathode to provide a more comprehensive view of the CBS interaction with Li metal and NMC cathode. It was observed that while CBS results in a more stable and uniform solid electrolyte interphase (SEI) on Li metal, it is incompetent in impeding Li dendrites. A potential method to reach a clearer understanding of the underlying mechanisms, involving the introduction of oxide coatings to the CBS separator, is explored. It is expected that this study will provide a fundamental understanding of the effects of cellulose on Li metal battery and further clarify its potential for next generation LIBs.

Bacterial nanocellulose (BNC) produced from sorbitol as a sustainable nano-filter for oil-water separation

Oil spillage is one of the serious problems for sustainable environment. Bacterial nanocellulose (BNC), a hydrophilic and highly porous material holds a promising material for oil-water separation from contaminants. In the present work, a hydrophilic BNC produced from a sorbitol as the carbon source demonstrated the unique porous symmetrical arrangement having an oleophilic property. The BNC membrane obtained showed the highest water holding capacity (WHC) of ≈147 gg 1. The Brunauer-Emmett-Teller (BET) analysis of BNC revealed the unique characteristics of isothermic patterns, having macro sized pores with diameter of 121.3 nm and surface area of 40.6m2/g, which plays a vital role in separation of oil from water by allowing passage of only water through it. The separation efficiency of BNC membrane produced after 5th day of incubation has showed 99.0 % oil removal compared to 10 and 15th day incubated BNC membranes. a CFD model to investigate the possibilities of BNC membranes and clarify the dynamics of oil-water separation. The nanostructured network of BNC offers a tortuous path for oil molecules while allowing rapid permeation of water, leading to high separation selectivity and flux. Although BNC has been previously studied for oil water separation, this study provides new insights into the use of wet BNC membranes into its pristine state with sorbitol as carbon source for this application.

In Situ Formation of Liquid Crystal Interphase for Aqueous Dual-Electrode-Free Batteries

Aqueous Zn/MnO₂ batteries have emerged as a promising solution in energy storage due to their inherent safety and environmental benefits. Over the past few decades, significant research efforts have been dedicated to enhancing their energy density and cycle life. However, challenges still remain in pushing these limits further, particularly with respect to simplifying battery design while maintaining performance and cost-efficiency. Traditional designs rely on separate anode and cathode materials, but a more streamlined approach could lead to breakthroughs in energy density and production costs.In this work, we present a transformative strategy aimed at creating an ultra-simplified Zn/MnO₂ battery, consisting only of current collectors and electrolyte, with no anode or cathode at the initial stage—what we call a dual-electrode-free battery (DEFB)1. This design achieves impressive energy densities of up to ~213 Wh/kg, setting new benchmarks for cost-effectiveness and energy storage potential. However, the irreversible deposition of Zn and MnO₂ has previously resulted in short battery lifespans, preventing practical applications of such batteries.Here we show that by leveraging soft template strategies, commonly used in material synthesis, we can overcome this limitation. We introduce trace amounts of surfactants into the electrolyte, triggering the in-situ formation of a liquid crystal interphase1. This novel interphase directs the deposition of Zn and MnO₂ along the c-axis, significantly enhancing the reversibility of deposition and stripping. As a result, we observe a substantial improvement in cycle life, with 80% capacity retention after 950 cycles—an unprecedented achievement for dual-electrode-free Zn/MnO₂ batteries. Our research highlights the innovative use of liquid crystals as an interphase, a concept rarely applied in the field of batteries. Traditionally, liquid crystals have been used as bulk electrolyte materials to enhance ionic transport, but their potential as a dynamic interphase layer has been untapped. By controlling the in-situ self-assembly processes of surfactant molecules into liquid crystal structures, we create a soft templating effect that enables highly reversible, patterned deposition. This process, confirmed through advanced soft matter characterizations such as cryo-TEM, marks a significant departure from traditional battery approaches, allowing for textured Zn and MnO₂ growth with minimal degradation. Moreover, this liquid crystal interphase chemistry holds promise for other electrode systems, such as cubic Cu, through the customization of liquid crystal phase structures. This opens up new possibilities for improving energy storage solutions2,3 beyond Zn/MnO₂ systems. Our method not only enhances the cycling stability of batteries but also provides a cost-effective and environmentally friendly pathway for advancing high-energy-density, long-cycle-life aqueous batteries.

Investigation of Electrospun Lignin Fiber Separators for Supercapacitor Applications

This research work investigates the potential of fossil-free electrospun lignin fibers (ELFs) as separators in supercapacitors, contrasting with commonly used commercial separators. We focus on ELFs derived from both hardwood and softwood wood derivatives, along with electrospun ELF with reduced graphene oxide (rGO), comparing their performance to eco-friendly cellulose separators.While polyolefin-based separators are prevalent in the industry, they often suffer from high production costs and limited performance due to sluggish ionic transfer kinetics and poor thermal stability 1. Separators play a critical role in battery performance, providing a microchannel for ion migration and affecting mechanical properties and safety. Lignin, with its high biocompatibility and stable aromatic rings, presents an attractive alternative material for separators2. Previous studies have demonstrated the potential of lignin-based separators, exhibiting high-rate capability and capacity retention compared to commercial separators. Lignin-polymer composite fibers, especially those with polyacrylonitrile (PAN) as the host polymer, have shown improved thermal stability, electrolyte affinity, and electrochemical performance. In our work, we aim to explore further the suitability of lignin-derived separators, particularly fossil-free ELFs and lignin nonwovens, for supercapacitor applications. By synthesizing nanofibers via electrospinning, we create separators with desirable pore properties and mechanical strength3. Our initial electrochemical investigations indicate promising results for ELF derived from both softwood and hardwood lignin, exhibiting specific capacitances of 174 F/g and 170 F/g, respectively. The nonwovens on the other hand demonstrate notably high specific capacitances, with 187 F/g surpassing conventional cellulose nonwovens at 173 F/g. These findings suggest that ELFs perform comparably to cellulose nonwovens, while lignin-based nonwovens exhibit superior performance. In large-scale applications, it's crucial to reduce the overall weight of individual supercapacitor devices. This helps improve their efficiency and ultimately makes them more affordable. One way to do this is by reducing the weight of separators inside the devices. Notably, the reduced mass of ELFs, nearly five times less than nonwoven counterparts, presents an avenue for improving overall component mass. Furthermore, ELFs demonstrate satisfactory rate capabilities comparable to nonwoven materials, further highlighting their potential for various applications. Moreover, lignin's substantially lower raw material costs compared to cellulose, even at its highest quality priced at 100-300 USD/milli ton, position it as an economically feasible alternative for separator material exploration 4. Employing lignin in nonwoven separators, particularly when utilizing inexpensive variants, offers a cost-effective solution for large-scale production of simple nonwoven fabrics. However, electrospinning, despite its advantages such as high surface area and precise fiber morphology control, typically entails higher expenses. Nevertheless, with the declining cost of lignin raw materials, electrospinning may become a more viable option. However, a thorough cost analysis, encompassing all relevant factors, remains essential for evaluating specific cases comprehensively. Furthermore, we intend to discuss more about the electrolyte absorption, mechanical properties, and thermal stability of these lignin-based separators compared to the commercial counterparts with continued investigation of this study. Therefore, through detailed characterization and electrochemical testing, we seek to elucidate the performance of the different separators in supercapacitors. Our findings aim to contribute to the development of sustainable and high-performance energy storage devices, leveraging lignin-derived materials as eco-friendly alternatives to traditional separators.

Hydrophilic Separator Stables CO2-to-C2H4 Conversion at Low Cell Voltage with Non-Noble Metal Anode

Electrochemical carbon dioxide (CO2) reduction (ECR) is a promising approach for enabling the conversion of greenhouse gas CO2 into valuable products with electricity from renewable sources to achieve net-zero CO2 emission. ECR simultaneously reduces carbon emissions and dependence on fossil-based fuels and chemicals. Membrane electrode assemblies (MEAs), which often comprise an anion exchange membrane (AEM) and a precious iridium oxide (IrOx)-based anode, have been extensively studied in the last few years. However, challenges such as salt precipitation on cathodic gas diffusion electrodes (GDEs), high cell voltage and the need to use noble metal anodes have hindered ECR's practical applications. Herein, we introduce a new design of MEA cells using a low-cost hydrophilic film separator and a Nickel (Ni) foam instead of AEM and IrOx, respectively. Hydrophilic separator material with high water permeability lowers the full-cell voltage and eliminates the salt accumulation on the GDE in both alkaline and neutral-pH conditions. Using copper-sputtered polytetrafluoroethylene (Cu/PTFE) as cathodes, we demonstrated a stable conversion of CO2 to ethylene (C2H4) at current densities over 100 mA/cm2. In neutral-pH anolyte, the average C2H4 FE was sustained at around 50% for more than 200 hours with a cell voltage of 3.1 V at the current density of 110 mA/cm2. Under alkaline conditions, this system showed 500 hours of stability of CO2-to-C2H4 conversion: the C2H4 FE was maintained above 60% with the cell voltage of only 2.2 V at 110 mA/cm2 current density. Our research provides a solution for achieving stable ECR operation at a relatively high current density using Earth-abundant materials. This work opens opportunities for energy-efficient and stable CO2 conversion without needing expensive and rare elements, which are crucial for practical applications.

Effective removal of Pb2+ from water by a novel magnetic Fe3O4-MnO2 composite prepared from steel pickling waste liquid: Adsorption behavior and mechanism

The high-value utilization of steel pickling waste liquid (SPWL) is an important direction in the resourceful utilization of hazardous waste. In this study, nano-Fe3O4 prepared from SPWL (S-Fe3O4) was hydrothermally compounded with MnO2 as Fe3O4-MnO2 (SFM), which were compared with Fe3O4-MnO2 (CFM) prepared by chemical reagents. The synthetic materials were evaluated by SEM, VSM, BET, XRD, and zeta potential, the results show that the spherical S-Fe3O4 was encapsulated by spiny spherical shell-like MnO2, and the SFM has a high saturation magnetization and specific surface area (159.91 m2/g). The adsorption experiments demonstrated that the adsorption effect of SFM on Pb2+ is highly similar to that of CFM. The maximal adsorption capacity of SFM reached 129.74 mg/g under ideal composite ratio and pH conditions, and the adsorption process was unaffected by competing heavy metal ions coexisting in the environment. Moreover, the high saturation magnetization strength of the SFM makes it simple to separate materials under a magnetic field. The pseudo-second-order kinetics and Langmuir isotherm models provided a good description of the Pb2+ adsorption on SFM. XPS and FTIR analysis provided evidence that the adsorbent surface has a high concentration of -OH functional groups, and that O atoms serve as Pb2+ binding sites, suggesting that ion exchange occurs during the SFM adsorption process. In this paper, we developed a cheap SFM with high adsorption performance and provided a novel approach to the high-value application of SPWL.

A Novel kgd-Topological Covalent Organic Framework with Optimum Pore Size for Efficient Benzene/Cyclohexane Separation.

Separation of benzene and cyclohexane is essential for obtaining high-purity cyclohexane in the chemical industry and for resource recovery from exhaust gas, but is one of the most challenging separation processes due to their highly similar boiling points and kinetic diameters. Herein, based on the isoreticular contraction strategy, a novel covalent organic framework (i.e., HFPB-TAB-COF) with kgd topological structure and average pore size of 5.70 Å, between the kinetic diameters of benzene (5.60 Å) and cyclohexane (6.10 Å), is synthesized for benzene/cyclohexane separation by pore confinement effect. HFPB-TAB-COF has the highest ideal adsorbed solution theory (IAST) selectivity of 36.0 for benzene/cyclohexane separation, and can produce 0.48mmol g-1 cyclohexane with purity of +99% from 50:50 (v:v) benzene/cyclohexane mixture under dynamic condition, higher than reported separation materials. Optimizing the pore size of COFs by isoreticular contraction strategy can trigger the pore confinement effect for better meeting the separation challenge in industry.

Dual-Asymmetric Janus Membranes Based on Two-Dimensional Nanowebs with Superspreading Surface for High-Performance Desalination.

Distillation membranes with hydrophobic surfaces and defined pores are considered a promising solution for seawater desalination. Most existing distillation membranes exhibit three-dimensional (3D) stacking bulk structures, where the zigzag water-repellent channels often lead to limited permeability and high energy costs. Here, we created two-dimensional nanowebs directly from the polymer/sol solution to construct dual-asymmetric Janus membranes. By tailoring the phase separation rate, the polymer phase evolved into continuous hydrophilic webs in situ weld on the microporous hydrophobic layer. The webs possess true-nanoscale architectures (internal fiber diameter of ∼20 nm, pore size of ∼140 nm) with enhanced roughness, serving as a superspreading surface to reach a water contact angle of 0° in 1.7 s. Benefiting from the architecture and wettability dual asymmetries, the obtained Janus membrane shows high-efficiency desalination performance (salt rejection >99%, flux of 11 kg m-2 h-1, and energy efficiency of 79%) with a thickness of 6.7 μm. Such a fascinating nanofibrous web-based Janus membrane may inspire the design of advanced liquid separation materials.

Advances in Membranes from Microporous Materials for Hydrogen Separation from Light Gases

With the pressing concern of the climate change, hydrogen will undoubtedly play an essential role in the future to accelerate the way out from fossil fuel‐based economy. In this case, the role of membrane‐based separation cannot be neglected since, compared with other conventional process, membrane‐based process is more effective and consumes less energy. Regarding this, metal‐based membranes, particularly palladium, are usually employed for hydrogen separation because of its high selectivity. However, with the advancement of various microporous materials, the status quo of the metal‐based membranes could be challenged since, compared with the metal‐based membranes, they could offer better hydrogen separation performance and could also be cheaper to be produced. In this article, the advancement of membranes fabricated from five main microporous materials, namely silica‐based membranes, zeolite membranes, carbon‐based membranes, metal organic frameworks/covalent organic frameworks (MOF/COF) membranes and microporous polymeric membranes, for hydrogen separation from light gases are extensively discussed. Their performances are then summarized to give further insights regarding the pathway that should be taken to direct the research direction in the future.

PEEK-PANI bi-functional oil-water separation membrane based on structural switchable wettability

Prewetting-induced switchable wettability materials demonstrate considerable potential for a diverse range of applications in comparison to traditional oil-water separation membranes including conventional special wetting materials, due to the distinctive advantages they offer. The current prewetting-induced switchable wettability materials are still constrained by the preparation strategy, separation performance and stability in practical application environment. This study presents a method for the preparation of PEEK/PANI bi-functional oil-water separation membranes by electrospinning and in-situ polyaniline growth. The controllable in-situ growth of PANI particles on PEEK fibers resulted in the formation of surface nano-micro structures, which enhanced the switchable underwater oleophobicity and underoil hydrophobicity of the membrane. The switching of wettability and the separation process is induced by prewetting in water or oil. The membranes display high permeability (maximum water flux of up to 8910 L⋅m−2⋅h−1) and separation efficiency (greater than 99.9 %) in gravity-driven oil-water mixtures/emulsion separation. PEEK-PANI composite fiber membranes demonstrate consistent separation performance in a range of corrosive or organic solvent environments due to the robust nature of the materials and the structural wettability This work presents a novel approach for the introduction of surface nano-micro structures and switchable structural wettability, as well as the production of high-performance multifunctional oil-water separation materials.

A Ni4O4-cubane-squarate coordination framework for molecular recognition

Molecular recognition is a fundamental function of natural systems that ensures biological activity. This is achieved through the sieving effect, host-guest interactions, or both in biological environments. Recent advancements in multifunctional proteins reveal a new dimension of functional organization that goes beyond single-function molecular recognition, emphasizing the need for artificial multifunctional materials in industrial applications. Herein, we have designed a porous Ni4O4-cubane squarate coordination polymer as an artificial molecular recognition host, drawing inspiration from the structural and functional features of natural enzymes. A comprehensive assessment of the material’s ability to distinguish target species under different operating conditions was carried out. The results confirm its sieving function through hexane isomers separation, host-guest interaction function via xenon/krypton separation, and dual presence of sieving and interaction through carbon dioxide/nitrogen separation. Additionally, the material demonstrates good stability and feasibility for large-scale production, indicating its practical potential. Our findings provide a bio-inspired multifunctional recognition material for chemical separations as proof-of-concept while offering solutions to advance artificial multifunctional materials adaptable to other applications beyond chemical separations.

Microfluidic Precision Manufacture of High Performance Liquid Chromatographic Microspheres

AbstractA key bottleneck in developing chromatographic material is the chemically entangled control of morphology, pore structure, and material chemistry, which holds back precision material manufacture in order to pursue advanced separation performance. In this work, a precision manufacture strategy based on droplet microfluidics was developed, for production of highly efficient chromatographic microspheres with independent control over particle morphology, pore structure and material chemistry. The droplet‐synthesized microspheres display extremely narrow particle size distribution (CV<3 %), enabling a 100 % production yield due to complete elimination of sieving steps. More importantly, the size of the droplet‐synthesized microspheres is freely adjustable without the need for re‐optimizing chemical recipes or reaction conditions. The resulting materials exhibit excellent separation efficiencies, achieving a reduced plate height of hmin=1.67. This precision manufacture strategy also allows for flexible pore design and continuous pore size adjustment across three orders of magnitudes, providing a novel vehicle for resolution fine‐tuning targeting protein separation. Besides traditional silica, organic–inorganic hybrid silica, zirconia, and titania microspheres can also be precisely synthesized on the same platform, supporting various separation applications and operating conditions. Powered by precision manufacture, super‐throughput production, and versatile chemistry, the high‐performance droplet‐synthesized separation material will pave the way towards green and precision chromatographic industry.