Lamellar Membranes Research Articles

Tuning Nanochannel Microenvironments of a Thermoresponsive MXene Membrane for Mixed Molecule Gradient Separation.

Drawing inspiration from dynamic biological ion channels, researchers have developed various artificial membranes featuring responsive nanochannels. Typically, these membranes modify mass transport behaviors by manipulating the responsive layer on the inner surfaces of the intrinsic layer. In this study, we build two-dimensional lamellar membranes composed of titanium carbide MXene and poly(N-isopropylacrylamide), endowed with dual-level regulatable nanochannels, achieved through adjustments of nanochannel microenvironments. The size of these two-dimensional nanochannels can be altered by both the thermoresponsive polymer layer and the intrinsic MXene layer that could undergo spontaneous oxidation. The multilevel regulation strategy substantially enhances the molecular selectivity of MXene separation membranes, which is further applied for precise gradient separation toward multiple molecules. This advancement showcases the versatility and transformative capabilities of responsive nanochannel technology, setting the stage for innovative developments in diverse fields.

Lamellar COF solid-state electrolytes for robust ambient-temperature lithium-ion transfer enhanced by PEI-driven channel alignment

Ionic covalent organic framework (COF) lamellar membranes are the alternative materials as promising Li+ conductors for all-solid-state lithium batteries. However, COF lamellar membrane suffers from poor structural stability and inevitable cross-layer transfer resistance due to the weak interaction at interface of adjacent nanosheets. Herein, a lamellar polymer-threaded ionic COF (PEI@TpPa-SO3Li) composite electrolyte with single Li+ conduction was prepared by assembling lithium sulfonated COF (TpPa-SO3Li) nanosheets and then threading them with polyethyleneimine (PEI) chains. It reveals that the threaded PEI chains induce the oriented permutation of pore channel of PEI@TpPa-SO3Li electrolyte through electrostatic interaction between –NH2/−NH− and –SO3Li groups. This enables the construction of continuous and aligned –SO3− … Li+ … −NH2/−NH− pairs along pore channels, which act as efficient Li+ conducting sites and afford high Li+ hopping conduction (1.4 × 10−4 S cm−1 at 30 °C) with a high Young's modulus of 408.7 MP and wide electrochemical stability window of 0∼4.7 V. The assembled LiFePO4||Li and LiNi0.8Mn0.1Co0.1O2||Li half-cells achieve high discharge capacities of 155.0 mAh g−1 and 167.2 mAh g−1 at 30 °C under 0.2 C, respectively, with high capacity retention of 98% after 300 cycles. This study provides an alternative route to highly ion-conductive lamellar porous electrolytes for high-performance energy devices.

Research Progress on the Regulation Methods for Selective Separation and Precise Control of Two-dimensional (2D) Lamellar Membranes

Selective separation and precise control of the structure and surface characterization for two-dimensional (2D) membranes is the key technology that requires to be revealed for further development of the material in practical application. Current researches focus on the cross-linking and modification of single nanosheet to improve and manipulate the performance of 2D lamellar membranes. In this paper, the selectivity principles such as size exclusion, charge properties, and surface chemical affinity in the separation process of 2D membranes were comprehensively and systematically reviewed, as well as the preparation of hybrid membranes combining the advantages of various raw materials. We also analyzed the practical application for the separation principles in relevant researches and discussed the development directions of 2D membranes. These inductions have certain summary and guiding significance for the selective regulation and goal-oriented design of 2D membranes.

Double bioinspired of robust BaSO4/SnO2 membrane with anti-crude oil adhesion and remarkable emulsion separation

Pollution from oily waste water is a serious environmental problem worldwide, causing serious damage to the environment and human health. At the same time, emulsifiers also cause great difficulties in wastewater treatment. Although efforts have been made to develop many high performance emulsion separation membranes, it is difficult to have the ability to resist crude oil pollution in practical applications. The construction of superoleophobic micro/nano-scale lamellar structured membranes with the potential to efficiently separate oil/water emulsions was inspired by the observation of bi-organisms, specifically the oil-resistant properties of fish scales and the unique adhesion of mussels. Tin dioxide, polydopamine and hydrophilic barium sulphate have been modified on the surface of stainless steel mesh by in-situ hydrothermal and dip coating. The superhydrophilic stainless steel mesh was successfully prepared by using the adhesion of polydopamine. Using the excellent underwater hydration ability of tin dioxide and the hydroxyl group-rich hydrophilic barium sulfate, the modified membrane showed excellent resistance to crude oil pollution. The superhydrophilic membrane can continuously separate different types of oil-in-water emulsions with high separation efficiency (99.9 %) and excellent separation flux (900 L m−2 h−1), with no decrease in efficiency and flux after 10 emulsion separation cycles. In addition, the superhydrophilic membrane has excellent durability and stability, remaining super-oleophobic underwater to sand shock, sandpaper abrasion, high saline corrosion and UV ageing. The prepared stainless steel membrane not only provides a novel anti-fouling strategy, but its excellent stability also provides some new inspiration for the treatment of oil and water pollution in the future.

Adipic acid-mediated hydrogen bonding network allocation for efficient proton conduction in water-stabilized lamellar MOF membranes

The poor water-stability and cross-layer proton transfer property pose a challenge to the lamellar metal–organic frameworks (MOFs) membrane when acting as a promising proton exchange membrane. Herein, we report an adipic acid-mediated strategy to improve the water-stability and the cross-layer proton conductivity of CuTCPP lamellar MOF membrane, which achieves a maximum power density and current density of 112.6 mW cm−2 and 424.4 mA cm−2, respectively. Adipic acid with extra functional groups (–PO3H2, –COOH) stably bridges the adjacent crystal layers via the terminal carboxylic acid anchoring Cu sites. In particular, the extra functional groups introduced into the adipic acid regulate the allocation of hydrogen bonding networks in an umbrella-shape around adipic acid with copper-porphyrin structures as external margin, enriching the coherence of hydrogen bonding network on the proton transport path. Benefiting from the regular pore structure of MOF, the optimized hydrogen bonding networks in adjacent crystal layers construct a more abundant through-plane transfer pathway. The resultant through-plane proton conductivities of CuTCPP-PO3H2/–COOH membranes are up to 108/89 mS cm−1 at 80 °C and 100 % RH, which is ∼ 6-fold higher than that of the pristine CuTCPP membrane (13 mS cm−1), with a conductivity attenuation of < 5 % during a humidity cycling test for 12 times.

Efficient removal of per- and polyfluoroalkyl substances by a metal-organic framework membrane with high selectivity and stability

Per- and polyfluoroalkyl substances (PFAS) in water requires sufficient removal due to their extreme chemical stability and potential health risk. Membrane separation can be a promising strategy, while membranes with conventional structures used for PFAS removal often face challenges such as limited efficiency and stability. In this study, a novel metal-organic framework (MOF) membrane with local modification of polyamide (PA) was developed by introducing interfacial polymerization process during the construction of lamellar membranes with MOF nanosheets. Benefiting from the dense structure and strong negative surface charge, the PA-modified MOF membrane could effectively remove 11 types of PFAS (five short-chain and six long-chain ones with molecular weights ranging from 214.0 to 514.1 Da), especially displaying high rejections for short-chain PFAS (over 84%), along with a remarkable water permeance of 21.4 L·m⁻²·h⁻¹·bar⁻1. The membrane removal characteristics for PFAS were deeply analyzed by elucidating various rejection mechanisms, with particularly distinguishing the rejection and adsorption capacity. Moreover, the membrane stability was significantly enhanced, demonstrated by the structural integrity after 10 min of ultrasonic treatment and stable separation efficiency over 120 h of continuous filtration. With enhanced surface hydrophilicity and negative charge as well as dense membrane pores, the novel membrane also exhibited more superior anti-fouling performance compared to conventional lamellar and PA membranes, further manifesting advantages for practical applications. This work provides a promising solution for developing high-performance membranes tailored specifically for efficient PFAS removal, addressing a critical need in water treatment.

Highly Efficient, Flexible, and Self-Healable Moisture-Driven Energy Harvester Based on 2D Vanadium Pentoxide Nanosheets

The ubiquitous source of atmospheric moisture brought about a fascinating research avenue of extracting atmospheric water to generate sustainable electricity. Energy may be extracted from ambient moisture with obvious and substantial advantages. This point-of-use technology provides a decentralized alternative to meet the energy needs in isolated off-grid places. Unlike traditional energy generators which predominantly rely upon fossil fuel, moisture-induced energy generators can extract energy from moisture in a sustainable and eco-friendly way. Herein, we demonstrated a self-healable moist electric generator (MEG) based on vanadium pentoxide (V2O5) 2D nanosheet membranes. Lamellar membranes of V2O5 nanosheets have been shown to be excellent cation conductors and excellent materials for harvesting energy from ambient moisture. Ultra-thin 2D nanosheets of V2O5 was obtained by treatment of bulk V2O5 crystals with hydrogen peroxide. V2O5 nanosheet membrane was fabricated by vacuum-assisted filtration of 2D V2O5 nanosheets dispersion over a PTFE support membrane. The V2O5 membrane was easily peeled off from the support membrane on drying to obtain a flexible and freestanding V2O5 membrane. The V2O5 membrane consisting of percolated nanofluidic channels was sandwiched between a bottom solid copper foil and a perforated copper foil as the bottom electrode. The top electrode is perforated for exposure to atmospheric humidity. As the atmospheric water molecules come in contact with the V2O5 surface, an open-circuit voltage of 0.5 Volts and a short-circuit current of 0.3 microamperes is generated. The generated voltage and current is attributed to the preferential flow of cations through the V2O5 nanochannels. The exposed surface and edges of V2O5 nanosheets have a high negative surface charge which results in the splitting of water molecules into H3O+ and OH- ions. An electrical double layer (EDL) is established at the V2O5/water interface which selectively permits H3O+ ions through the channels. The mobile ions of the EDL transport through the nanofluidic channels creating a gradient between the two electrodes, resulting in a constant potential difference between the top and bottom electrodes which is harvested as electric current. The MEGs can be easily connected in parallel or series to enhance the current and voltage respectively. We demonstrate ten MEGs connected in series to power small electronic devices such as calculators and humidity meters. One of the key features of the V2O5 MEG is its ability to repair any physical damage to the active material owing to the water-assisted healing characteristics V2O5 membrane. Figure 1

A Matthew MXene (Ti3C2Tx) Lamellar Membrane as a Potassium-Sieving Amplifier

Transport channels with ultrahigh K+ selectivity over other ions play a crucial role for living beings, but constructing ionic channels with promising K+ selectivity and permeability remains a challenge. Here, an asymmetric bilayer membrane based on MXene (Ti3C2Tx) lamellar channels consisting of a recognition layer (RL) on top of an enhancement layer (EL) exhibits an amazing Matthew effect: amplification of the preferred transport of K+, resulting in an excellent K+-separation performance. The K+ ion is selected by the 1-aza-18-crown-6 ether-modified RL, owing to preferential affinity energy, and then rapidly transported as a hydrated ion through the EL, based on the confinement effect. Other undesired ions such as Na+ are hindered from entering the RL by the preferred K+ occupation of the crown ether. The MXene (Ti3C2Tx)-based Matthew membrane presents high K+-permeation rates of 0.1–0.2 mol∙m–2∙h–1, with a significant K+/Na+ selectivity of 5–9. The molecular separation mechanism of the Matthew membrane is investigated deeply to explore the nature of the Matthew amplification effect on K+ sieving, where the precise matching of the RL and EL within the membrane governs the fast K+ permeation with good selectivity. The asymmetric structure of our Matthew membrane is the key to understanding the biological function of ion channels for precise and fast ion transport, which will guide us in the creation of artificial ion channels or membranes.

Photocatalytically self-cleaning graphene oxide nanofiltration membranes reinforced with bismuth oxybromide for high-performance water purification

Graphene oxide (GO) membranes have emerged as promising candidates for water purification applications, owing to their unique physicochemical attributes. Nevertheless, the trade-off between permeability and selectivity, coupled with their vulnerability to membrane fouling, poses significant challenges to their widespread industrial deployment. In this study, we introduce an innovative in-situ growth and layer-by-layer assembly technique for fabricating multilayer GO membranes reinforced with bismuth oxybromide (BiOBr) on commonly employed Nylon substrates. This method allows for the creation of two-dimensional lamellar membranes capable of photocatalytic self-cleaning and tunable nanochannel dimensions. The synthesized GO/BiOBr composite membranes exhibit remarkable water permeance rates (approximately 493.9 LMH/bar) and high molecular rejection efficiency (>99 % for Victoria Blue B and Congo Red dyes). Notably, these membranes showcase an enhanced photocatalytic self-cleaning performance upon exposure to visible light. Our work provides a viable route for the fabrication of functionalized GO-based nanofiltration membranes with BiOBr inclusions, offering a synergistic combination of high water permeability, modifiable nanochannels, and effective self-cleaning capabilities through photocatalysis.

Novel ultrastable 2D MOF/MXene nanofluidic membrane with ultralow resistance for highly efficient osmotic power harvesting

Two-dimensional (2D) materials have shown great potential in harvesting osmotic power due to their high membrane selectivity, but the high resistance from tortuous pathways of 2D nanofluidic membranes still impedes the further improvement in output performance. Here, we report an innovative 2D MXCT (MXene/Cu-TCPP) lamellar membrane with ultralow resistance for highly efficient osmotic power generation. The incorporation of 2D Ti3C2Tx MXene with rich functional groups not only resolves the water-stability issue of 2D metal-organic framework (MOF) Cu-TCPP, but provides large surface charges for selective ion transport. The orderly sub-2 nm framework channels of Cu-TCPP provide much shorter permeation pathways for fast ion transport, thus endowing the MXCT membrane with ultralow resistance. Consequently, the MXCT membrane reaches an ultrahigh power output of ∼8.29 W/m2 by mixing seawater and river water, which is ∼275 % higher than that of the pristine MXene membrane. Additionally, it outperforms all the reported single-layer 2D nanosheet-based osmotic power generators under the same experimental conditions in terms of output power and internal resistance (9 kΩ). This work presents a reliable strategy for stabilizing 2D Cu-TCPP MOF in electrolytes, opening new avenues for designing promising 2D nanofluidic membranes for efficient blue energy harvesting and ionic devices.

High performance lamellar structured graphene oxide nanocomposite membranes via Fe3O4-coordinated phytic acid control of interlayer spacing for organic solvent nanofiltration (OSN)

Graphene oxide (GO), a 2D nanomaterial known for its precise molecular sieving, holds potential for Organic Solvent Nanofiltration (OSN) and wastewater treatment. However, challenges such as thin interlayer spacing, extended diffusion pathways, and susceptibility to dehydration and negative charge-induced swelling limit its separation performance. To overcome these limitations, Herein, we have fabricated novel Fe3O4 coordinated PhA intercalated GO nanocomposite membranes. Impressively, these nanocomposite membranes exhibited remarkable separation efficiency for dyes, pesticides, and pharmaceutical ingredients, addressing the drawbacks associated with pristine GO membranes and enhancing their overall performance. The optimum G10(1)/P1.5-F100µL nanocomposite membrane displayed impressive solvent permeance of 40.43, 33.45, 20.70, 16.24, and 5.6 L/m2 h bar for acetone, methanol, water, ethanol, and IPA, respectively, while maintaining a rejection rate of ≥98.97 % for the MO dye (MW = 327.33 g/mol). Furthermore, the membrane exhibited outstanding efficiency in separating tetracycline (TC) in ethanol (≥97.97 %) and Pendimethalin (PM) in water (≥99.88 %). Additionally, it demonstrated high rejection capabilities for MB (≥98 %) and CR (≥98.78 %) in harsh DMF solvent. Importantly, the nanocomposite membrane displayed outstanding durability throughout continuous separation of Pendimethalin (PM) in a water solution over a period of 168 h. The PM separation remained nearly unchanged for the entire 168-h duration, demonstrating high mechanical strength and chemical stability. Additionally, the single nanocomposite membrane showcased high efficiency in feed change separation, successfully separating CR in ethanol and PM in water. These results, compared to the other GO-based nanocomposite membranes, demonstrate the exceptional stability and immense potential for real OSN applications.

Polymer-functionalized metal-organic framework nanosheet membranes for efficient CO2 capture

Two-dimensional metal-organic frameworks (2DMOFs) have emerged as highly appealing candidates as advanced separation membrane materials. However, constructing 2DMOF membranes with appropriate channel sizes to separate CO2 from N2 remains a great challenge. Here, we propose an in-situ crystallization approach to synthesize CO2-philic-polymer functionalized Zr-based MOF nanosheets, enabling the fabrication of efficient CO2 capture membranes. The in-situ MOF crystallization with polyethylenimine (PEI) polymers leads to a uniform distribution of amines, resulting in the formation of PEI-NUS hybrid nanosheet characterized by both high porosity and strong affinity to CO2. These nanosheets are assembled into ultrathin lamellar membranes with thicknesses ranging from 40 to 120 nm. The amines of PEI polymers significantly facilitate the CO2 transfer as reaction carriers, resulting in a substantially improved CO2/N2 separation performance with a CO2 permeance of 410 GPU and a CO2/N2 selectivity of 90, which are among the best for MOF membranes in CO2 separation. This in-situ functionalization strategy paves the way for the fabrication of ultrathin 2D membranes for various separations.

Multidimensional Spectral Phasors of LAURDAN's Excitation-Emission Matrices: The Ultimate Sensor for Lipid Phases?

The impact of lipid diversity on the lateral organization of biological membranes remains a topic of debate. While the existence of domains in lamellar membranes is well-established, the nonlamellar phases occurring in biological systems are less explored due to technical constraints. Here, we present the measurement of the excitation-emission matrices (EEM) of LAURDAN in several lipid structures. LAURDAN is a fluorescence probe widely used for characterizing lipid assemblies. The EEMs were analyzed by multidimensional spectral phasors (MdSP), an approach that seizes information from both the excitation and emission spectra. We developed a computer algorithm to construct EEM data based on a model for LAURDAN's photophysics. The MdSP calculated from the simulated EEMs reveals that all feasible possibilities lie inside a universal triangle in the phasor's plot. We use this triangle to propose a ternary representation for the phasors, allowing a better assessment of LAURDAN's surroundings in terms of hydration, water mobility, and local electronic environment. Building upon this foundation, we constructed a theoretical "phase map" that can assess both lamellar and nonlamellar membranes. We thoroughly validated this theory using well-known lipid mixtures under different phase-state conditions and enzymatically generated systems. Our results confirm that the use of MdSP is a powerful tool for obtaining quantitative information on both lamellar and nonlamellar structures. This study not only advances our understanding of the impact of lipid diversity on membrane organization but also provides a robust and general framework for the assessment of fluorescence properties that can be further extended to other probes.

Built-in Electric Fields in Heterostructured Lamellar Membranes Enable Highly Efficient Rejection of Charged Mass.

Separation membranes with homogeneous charge channels are the mainstream to reject charged mass by forming electrical double layer (EDL). However, the EDL often compresses effective solvent transport space and weakens channel-ion interaction. Here, built-in electric fields (BIEFs) are constructed in lamellar membranes by assembling the heterostructured nanosheets, which contain alternate positively-charged nanodomains and negatively-charged nanodomains. We demonstrate that the BIEFs are perpendicular to horizontal channel and the direction switches alternately, significantly weakening the EDL effect and forces ions to repeatedly collide with channel walls. Thus, highly efficient rejection for charged mass (salts, dyes, and organic acids/bases) and ultrafast water transport are achieved. Moreover, for desalination on four-stage filtration option, salt rejection reaches 99.9 % and water permeance reaches 19.2 L m-2 h-1 bar-1. Such mass transport behavior is quite different from that in homogeneous charge channels. Furthermore, the ion transport behavior in nanochannels is elucidated by validating horizontal projectile motion model.

Nuclear receptors for epidermal lipid barrier: Advances in mechanisms and applications.

The skin plays an essential role in preventing the entry of external environmental threats and the loss of internal substances, depending on the epidermal permeability barrier. Nuclear receptors (NRs), present in various tissues and organs including full-thickness skin, have been demonstrated to exert significant effects on the epidermal lipid barrier. Formation of the lipid lamellar membrane and the normal proliferation and differentiation of keratinocytes (KCs) are crucial for the development of the epidermal permeability barrier and is regulated by specific NRs such as PPAR, LXR, VDR, RAR/RXR, AHR, PXR and FXR. These receptors play a key role in regulating KC differentiation and the entire process of epidermal lipid synthesis, processing and secretion. Lipids derived from sebaceous glands are influenced by NRs as well and participate in regulation of the epidermal lipid barrier. Furthermore, intricate interplay exists between these receptors. Disturbance of barrier function leads to a range of diseases, including psoriasis, atopic dermatitis and acne. Targeting these NRs with agonists or antagonists modulate pathways involved in lipid synthesis and cell differentiation, suggesting potential therapeutic approaches for dermatosis associated with barrier damage. This review focuses on the regulatory role of NRs in the maintenance and processing of the epidermal lipid barrier through their effects on skin lipid synthesis and KC differentiation, providing novel insights for drug targets to facilitate precision medicine strategies.

Tuning the interlayer spacing of graphene oxide membrane via surfactant intercalation for ultrafast nanofiltration

A facile method has been developed to fabricate lamellar composite graphene oxide (CGO) membranes by incorporating positively charged surfactants – cetyltrimethylammonium bromide (CTAB). The interlayer spacing of GO nanosheets was regulated by the sum of both vertical and horizontal alignment of CTAB on the GO surface via electrostatic interaction. The CTAB intercalated GO membrane exhibited an internal layer spacing of 16.97 Å compared to 8.26 Å for the GO membrane. The obtained CGO lamellar membrane with well-defined nanochannels showed ultrafast pure water flux of ∼1112 L h−1 m−2 bar−1 and an excellent separation efficiency of >99 % towards negatively charged organic dye molecules at a high permeation flux of ∼932 L h−1 m−2 bar−1, which was nearly 2.5-fold enhancement compared with that of the pristine GO membrane (∼400 L h−1 m−2 bar−1). The electrostatic and π–π interaction forces between the CGO membrane and organic dye molecules played a major role in the overall dye separation mechanism. Furthermore, the CGO membrane demonstrated excellent stability with no loss in separation performance (>96 % organic molecules rejection) after exposure to various pH solutions and deionized water (DI) water. The current work provides a straightforward approach for the formation of highly tunable and stable CTAB-intercalated GO membranes for ultrafast molecular separation.

Designing Nanofluidic Channels of Boron Nitride Nanosheets/Aramid Nanofibers/Covalent Organic Frameworks Nanofiltration Membrane for Ultrafast Mass Transport.

2D lamellar nanofiltration membrane is considered to be a promising approach for desalinating seawater/brackish water and recycling sewage. However, its practical feasibility is severely constrained by the lack of durability and stability. Herein, a ternary nanofiltration membrane via a mixed-dimensional assembly of 2D boron nitride nanosheets (BNNS) is fabricated, 1D aramid nanofibers (ANF), and 2D covalent organic frameworks (COF). The abundant 2D and 1D nanofluid channels endow the BNNS/ANF/COF membrane with a high flux of 194 L·m‒2·h‒1. By the synergies of the size sieving and Donnan effect, the BNNS/ANF/COF membrane demonstrates high rejection (among 98%) for those dyes whose size exceeds 1.0nm. Moreover, the BNNS/ANF/COF membrane also exhibits remarkable durability and mechanical stability, which are attributed to the strong adhesion and interactions between BNNS, ANF, and COF, as well as the superior mechanical robustness of ANF. This work provides a novel strategy to develop robust and durable 2D lamellar nanofiltration membranes with high permeance and selectivity simultaneously.

Comparative Retention Analysis of Intercalated Cations Inside the Interlayer Gallery of Lamellar and Nonlamellar Graphene Oxide Membranes in Reverse Osmosis Process: A Molecular Dynamics Study.

Over the past decade, multilayered graphene oxide (GO) membranes have emerged as promising candidates for desalination applications. Despite their potential, a comprehensive understanding of separation mechanisms remains elusive due to the intricate morphology and structural arrangement of interlayer galleries. Moreover, a critical concern of multilayered GO membranes is their susceptibility to swelling within aqueous environments, which hinders their practical implementation. Therefore, this study introduces cation intercalation within GO laminates to elucidate the underlying factors governing swelling behavior and subsequently mitigate it. Moreover, this study performed nonequilibrium molecular dynamics simulations on the cation (Mg2+ or K+)-intercalated lamellar and nonlamellar GO membranes to understand the effect of the arrangement of GO sheets on the retention time of intercalated cations within GO layers, water permeance, and salt rejection mechanism in the reverse osmosis process using cation-intercalated GO membranes. Our results highlight that lamellar GO membranes exhibit higher water permeance, attributed to their well-defined interlayer gallery structure. On the other hand, nonlamellar GO membranes display superior salt rejection due to their complex interlayer gallery structure that impedes salt permeation. Moreover, the structural complexity of nonlamellar GO membranes contributes to greater stability by retention of the more intercalated cations for a longer time within the layers. Furthermore, it is observed that a higher percentage of Mg2+ cations remained inside the GO laminates as compared to K+ cations, hence resulting in the greater stability of the Mg2+-intercalated GO membrane in the aqueous environment.

Bendable, lamellar MXene membrane electrodes with diverse diffusion pathways for potential application in miniaturized capacitive deionization devices

Flexible devices have shown great application potential in portable and miniaturized devices. However, work on flexible electrodes for capacitive deionization (CDI) has not been well developed due to the issues of desalination property, processability, and availability under actual bending conditions. Herein, we constructed a kind of flexible lamellar MXene membrane by assembling Ti3C2Tx sheets with both crumpled and perforated structures and studied their desalination performance in conventional planar and bent configurations. The crumpled and perforated features in Ti3C2Tx (C-P-TC) nanosheets could optimize the in-plane and out-of-plane diffusion channels of the stacked samples, respectively, effectively improving the accessibility of membranes. As a result, the desalination performance of such C-P-TC electrodes was superior to that of those assembled from crumpled or perforated sheets alone. Significantly, this flexible C-P-TC electrode still showed excellent performance at real bend deformation, which possessed not only almost the same CDI capacity as the traditional planar configuration but also good cycling stability. This work not merely proposes an alternative strategy to improve the CDI performance of lamellar MXene electrodes by regulating the nanostructures of channels but also confirms their effective deionization ability under real bent state, greatly facilitating the potential use of flexible electrodes in miniaturized CDI devices.

A multistage assembled laminar membrane for solar thermal conversion and nighttime electricity production

Interfacial solar-driven evaporation technology has great potential to address freshwater shortages. Despite significant progress in developing efficient evaporators, the challenge of evaporation rates of two-dimensional evaporators still needs to be solved. In addition, interfacial solar-driven evaporation relies on solar energy to trigger the evaporation of thin water layers at the water–air interfaces. It thus may be at risk of interruption in the absence of sunlight. To overcome these challenges, we have intelligently assembled different functional components to form a multistage assembled laminar membrane used for interfacial solar-driven evaporation during the day and power generation at night. Specifically, solar evaporation achieved a high evaporation rate of 1.78 kg m−2h−1 under single solar irradiation. Desalination and water purification capabilities were also demonstrated. More notably, the membrane also showed its worth as an electrical generator in overcast weather or nights, delivering a voltage of 309 mV and a current of 2 μA. The voltage and current can be multiplied by connecting four membranes in series and parallel to 1.1 V and 8.8 μA, respectively. This powers a calculator directly and stores excess electricity in a capacitor, which can be as high as 2 V in 2000 s. This innovation shows promising applications in next-generation freshwater production and power generation.