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As the atmospheric carbon dioxide (CO2) concentration rapidly rises, carbon capture, utilization, and storage (CCUS) is an emerging field for climate change mitigation. Various carbon capture technologies are in development with the help of adsorbents, membranes, solvent-based systems, etc. One of the main challenges in this field is the removal of CO2 from nitrogen (N2) gas. This paper focuses on mixed matrix membrane technology, for which the CO2/N2 separation performance is based on differences in gas permeations. Membrane separation and purification technologies are widely studied for carbon capture. Microporous adsorbents such as zeolites and metal organic frameworks (MOFs) for carbon capture have been attracting researchers' attention due to their highly porous structures, high selectivity values, and tunable porosities. Utilizing microporous adsorbents dispersed within a novel, blended polymer matrix, fourteen membranes were prepared with the commercial MOF ZIF-8, zeolite 13X, and kaolin, with methyl cellulose (MC) and polyvinyl alcohol (PVA), which were tested using a single gas permeation setup in this study. The addition of polyallylamine (PAH) as a chemisorbent was also investigated. These membranes were synthesized both with and without a polyacrylonitrile (PAN) support to compare their performances. MC was found to be an ideal polymeric matrix component to develop free-standing MMMs. At 24 °C and a relatively low feed pressure of 2.36 atm, a free-standing zeolite-13X-based membrane (MC/PAH/13X/PVA) exhibited the highest N2/CO2 selectivity of 2.8, with a very high N2 permeability of 6.9 × 107 Barrer. Upon the optimization of active layer thickness and filler weight percentages, this easily fabricated free-standing MMM made of readily available materials is a promising candidate for CO2 purification through nitrogen removal. [ABSTRACT FROM AUTHOR]

As the atmospheric carbon dioxide (CO2) concentration rapidly rises, carbon capture, utilization, and storage (CCUS) is an emerging field for climate change mitigation. Various carbon capture technologies are in development with the help of adsorbents, membranes, solvent-based systems, etc. One of the main challenges in this field is the removal of CO2 from nitrogen (N2) gas. This paper focuses on mixed matrix membrane technology, for which the CO2/N2 separation performance is based on differences in gas permeations. Membrane separation and purification technologies are widely studied for carbon capture. Microporous adsorbents such as zeolites and metal organic frameworks (MOFs) for carbon capture have been attracting researchers’ attention due to their highly porous structures, high selectivity values, and tunable porosities. Utilizing microporous adsorbents dispersed within a novel, blended polymer matrix, fourteen membranes were prepared with the commercial MOF ZIF-8, zeolite 13X, and kaolin, with methyl cellulose (MC) and polyvinyl alcohol (PVA), which were tested using a single gas permeation setup in this study. The addition of polyallylamine (PAH) as a chemisorbent was also investigated. These membranes were synthesized both with and without a polyacrylonitrile (PAN) support to compare their performances. MC was found to be an ideal polymeric matrix component to develop free-standing MMMs. At 24 °C and a relatively low feed pressure of 2.36 atm, a free-standing zeolite-13X-based membrane (MC/PAH/13X/PVA) exhibited the highest N2/CO2 selectivity of 2.8, with a very high N2 permeability of 6.9 × 107 Barrer. Upon the optimization of active layer thickness and filler weight percentages, this easily fabricated free-standing MMM made of readily available materials is a promising candidate for CO2 purification through nitrogen removal.

To enhance the energy density of batteries and explore intrinsic charge storage mechanism of the active materials, it is important to reduce or eliminate the use of non‐active materials in electrodes, such as binder and conductive additives. Herein, free‐standing Na4MnV(PO4)3@C (F‐NMVP@C) fiber membrane is fabricated and directly used as a sodium‐ion battery (SIB) cathode. In situ X‐ray diffraction reveals that the V3+/V4+ redox reaction occurs through a solid‐solution reaction while a two‐phase Mn2+/Mn3+ redox reaction is identified, and both are highly reversible. Meanwhile, ex situ electrochemical impedance spectroscopy reveals that both the ion diffusion coefficient and charge transfer resistance of F‐NMVP@C change reversibly during the Na+ intercalation/de‐intercalation. Battery full cells are assembled based on the free‐standing F‐NMVP@C cathodes and F‐Sb@C anodes, which manifests a high energy density (293 Wh kg−1) and good cyclability (87.5% after 100 cycles at 1 C). The high‐performance free‐standing cathodes and anodes shed light on the development of flexible SIBs. [ABSTRACT FROM AUTHOR]

In 2D materials, a key engineering challenge is the mass production of large-area thin films without sacrificing their uniform 2D nature and unique properties. Here, it is demonstrated that a simple fluid phenomenon of water/alcohol solvents can become a sophisticated tool for self-assembly and designing organized structures of 2D nanosheets on a water surface. In situ, surface characterizations show that water/alcohol droplets of 2D nanosheets with cationic surfactants exhibit spontaneous spreading of large uniform monolayers within 10 s. Facile transfer of the monolayers onto solid or flexible substrates results in high-quality mono- and multilayer films with high coverages (>95%) and homogeneous electronic/optical properties. This spontaneous spreading is quite general and can be applied to various 2D nanosheets, including metal oxides, graphene oxide, h-BN, MoS 2 , and transition metal carbides, enabling on-demand smart manufacture of large-size (>4 inchϕ) 2D nanofilms and free-standing membranes., (© 2024 Wiley‐VCH GmbH.)

Graphene-based materials have been extensively investigated as light converters for photothermal therapy, energy harvesting, and laser ignition owing to their good light absorption and high thermal conductivity. Further, the energy output of pure graphene materials as laser converters is relatively low. In this paper, we reported the introduction of ammonium nitrate (AN) into graphene oxide (GO) for the preparation of free-standing, graphene-based membranes using anti-solvent method and vacuum filtration. They showed good light absorption and energy output, leading to excellent photothermal performance owing to the synergistic reaction between GO and AN. The existence of AN was confirmed by scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy analyses. The influence of GO and NH4NO3 on the photothermal performance of the composite membranes was entirely investigated by ultraviolet, thermal gravimetric analysis, and differential scanning calorimetry analyses. The heat release and the maximum heat release rate of the G20N5 film were 1030 ​J·g−1 and 8.9 ​J·g−1s−1, respectively, which were much higher than those of the pure GO. The flame produced by the laser irradiation was captured by a high-speed camera. The prepared G20N5 film showed the best performance among all the samples. Compared with pure GO (approximately 300 ​°C at 0.7 ​W), the temperature of the G20N5 composite film was dramatically increased (approximately 450 ​°C at 0.7 ​W) under the same power of the pulse laser irradiation, which is important for the potential application of optical ignition with low initiating energy.

As a new class of crystalline porous organic materials, covalent organic frameworks (COFs) have attracted considerable attention for proton conduction owing to their regular channels and tailored functionality. However, most COFs are insoluble and unprocessable, which makes membrane preparation for practical use a challenge. In this study, we used surface‐initiated condensation polymerization of a trialdehyde and a phenylenediamine for the synthesis of sulfonic COF (SCOF) coatings. The COF layer thickness could be finely tuned from 10 to 100 nm by controlling the polymerization time. Moreover, free‐standing COF membranes were obtained by sacrificing the bridging layer without any decomposition of the COF structure. Benefiting from the abundant sulfonic acid groups in the COF channels, the proton conductivity of the SCOF membrane reached 0.54 S cm−1 at 80 °C in pure water. To our knowledge, this is one of the highest values for a pristine COF membrane in the absence of additional additives. [ABSTRACT FROM AUTHOR]

Free-standing poly(ethylene glycol) (PEG) membranes were prepared from amine- and epoxy-terminated four-arm STAR-PEG precursors in a thickness range of 40–320 nm. The membranes feature high stability and an extreme elasticity, as emphasized by the very low values of Young’s modulus, varying from 2.08 MPa to 2.6 MPa over the studied thickness range. The extreme elasticity of the membranes stems from the elastomer-like character of the PEG network, consisting of the STAR-PEG cores interconnected by crosslinked PEG chains. This elasticity is only slightly affected by a moderate reduction in the interconnections at a deviation from the standard 1:1 composition of the precursors. However, both the elasticity and stability of the membranes are strongly deteriorated by a strong distortion of the network imposed by electron irradiation of the membranes. In contrast, exposure of the membranes to ultraviolet (UV) light (254 nm) does not affect their elastic properties, supporting the assumption that the only effect of such treatment is the decomposition of the PEG material with subsequent desorption of the released fragments. An analysis of the data allowed for the exclusion of so called “hot electrons” as a possible mechanism behind the modification of the PEG membranes by UV light.

This work is the first reporting the use of layer-by-layer to produce adhesive free-standing (FS) films fully produced using natural-based macromolecules: chitosan (CHI), alginate (ALG) and sulfated levan (L-S). The deposition conditions of the natural polymers were studied through zeta potential measurements and quartz crystal microbalance with dissipation monitoring analysis. The properties of the FS films were evaluated and compared with the control ones composed of only CHI and ALG in order to assess the influence of levan polysaccharide introduced in the multilayers. Tensile tests, dynamic mechanical analysis and single lap shear strength tests were performed to evaluate the mechanical properties of the prepared FS films. The presence of L-S conferred both higher tensile strength and shear strength to the developed FS membranes. The results showed an adhesion strength 4 times higher than the control (CHI/ALG) FS films demonstrating the adhesive character of the FS films containing L-S. Morphological and topography studies were carried out revealing that the crosslinking reaction granted the L-S based FS film with a higher roughness and surface homogeneity. Preliminary biological assays were performed by cultivating myoblasts cells on the surface of the produced FS films. Both crosslinked and uncrosslinked FS films containing L-S were cytocompatible and myoconductive. Statement of Significance Sutures remain as the “gold standard” for wound closure and bleeding control; however they still have limitations such as, high infection rate, inconvenience in handling, and concern over possible transmission of blood-borne disease through the use of needles. One of the challenges of tissue engineering consist on the design and development of biocompatible tissue adhesives and sealants with high adhesion properties to repair or attach devices to tissues. In this work, the introduction of sulfated levan (L-S) on multilayered free-standing membranes was proposed to confer adhesive properties. Moreover, the films were myoconductive even in the absence of crosslinking just by the presence of L-S. This study provides a promising strategy to develop biological adhesives and for cardiac tissue engineering applications. [ABSTRACT FROM AUTHOR]

Three structures: free-standing Ta 2 O 5 nanotube membranes, adhered Ta 2 O 5 nanotube arrays and spark discharge Ta 2 O 5 films, have been fabricated respectively by anodizing pure Ta for one hour in three different using stages of the same original concentration electrolyte consisting of 96 vol% H 2 SO 4 (95–98%) and 4 vol% HF (48%) in this work. Stage I: In the 0–10 hours used electrolyte, patchy free-standing Ta 2 O 5 nanotube membranes formed within the potential range of 10 V–70 V; Stage II: In the 30–50 hours used solution, highly ordered amorphous adhered Ta 2 O 5 nanotube arrays with top diameter of 40 nm–270 nm and length of 5 μm–122 μm were fabricated during 10 V–170 V; Stage III: When the using time of electrolyte exceeded 50 hours, spark discharge films with Ta 2 O 5 crystal phase formed at 180 V–200 V, and nanotube structure still remained partially in the spark discharge films. The diameter of Ta 2 O 5 nanotubes increases with the increasing of voltage. In addition to Ta and O elements, adhered Ta 2 O 5 nanotube array films contain a small amount of S and F elements, but the spark discharge Ta 2 O 5 films do not consist of S element. Adhered Ta 2 O 5 nanotube arrays and spark discharge Ta 2 O 5 films show excellent hydrophilicity. The current density-time curves of adhered Ta 2 O 5 nanotube arrays obtained at high voltage (70 V–170 V) exhibit unique fluctuation phenomena and the current oscillation behaviors have a significant influence on the morphologies of nanotube array. Moreover, irritating gases emission on anode and light yellow sediment on cathode occur in the anodization process of Ta 2 O 5 nanotube arrays. This work obtains Ta 2 O 5 nanotube arrays with various structure parameters and expands anodic Ta 2 O 5 film fabrication windows using HF/H 2 SO 4 electrolyte at different stages, meanwhile provides the detailed analyses for growth mechanism of Ta 2 O 5 nanotube arrays. Our results are expected to provide references for the nanostructure preparation on the surface of other metals and alloys by anodization. [ABSTRACT FROM AUTHOR]

Free-standing (FS) membranes have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we studied the potential of free-standing membranes made by the layer-by-layer assembly of chitosan and alginate to be used as a simple biomimetic system of the periosteum. The design of a periosteum-like membrane implies the elaboration of a thick membrane suitable for both muscle and bone formation. Our aim was to produce well-defined ∼50 μm thick polysaccharide membranes that could be easily manipulated, were mechanically resistant, and would enable both myogenesis and osteogenesis in vitro and in vivo. The membranes were chemically crosslinked to improve their mechanical properties. Crosslinking chemistry was followed via Fourier transform infrared spectroscopy and the mechanical properties of the membranes were assessed using dynamic mechanical analysis. The loading and release of the potent osteoinductive growth factor bone morphogenetic protein 2 (BMP-2) inside and outside of the FS membrane was followed by fluorescence spectroscopy in a physiological buffer over 1 month. The myogenic and osteogenic potentials of the membranes in vitro were assessed using BMP-2-responsive skeletal myoblasts. Finally, their osteoinductive properties in vivo were studied in a preliminary experiment using a mouse ectopic model. Our results showed that the more crosslinked FS membranes enabled a more efficient myoblast differentiation in myotubes. In addition, we showed that a tunable amount of BMP-2 can be loaded into and subsequently released from the membranes, depending on the crosslinking degree and the initial BMP-2 concentration in solution. Only the more crosslinked membranes were found to be osteoinductive in vivo. These polysaccharide-based membranes have strong potential as a periosteum-mimetic scaffold for bone tissue regeneration. [ABSTRACT FROM AUTHOR]

Partially amorphous La0.6Sr0.4CoO3- δ (LSC) thin-film cathodes are fabricated using pulsed laser deposition and are integrated in free-standing micro-solid oxide fuel cells (micro-SOFC) with a 3YSZ electrolyte and a Pt anode. A low degree of crystallinity of the LSC layers is achieved by taking advantage of the miniaturization of the cells, which permits low-temperature operation (300-450 °C). Thermomechanically stable micro-SOFC are obtained with strongly buckled electrolyte membranes. The nanoporous columnar microstructure of the LSC layers provides a large surface area for oxygen incorporation and is also believed to reduce the amount of stress at the cathode/electrolyte interface. With a high rate of failure-free micro-SOFC membranes, it is possible to avoid gas cross-over and open-circuit voltages of 1.06 V are attained. First power densities as high as 200-262 mW cm−2 at 400-450 °C are achieved. The area-specific resistance of the oxygen reduction reaction is lower than 0.3 Ω cm2 at 400 °C around the peak power density. These outstanding findings demonstrate that partially amorphous oxides are promising electrode candidates for the next-generation of solid oxide fuel cells working at low-temperatures. [ABSTRACT FROM AUTHOR]

Free-standing poly(ethylene glycol) (PEG) membranes were prepared from amine- and epoxy-terminated four-arm STAR-PEG precursors in a thickness range of 40-320 nm. The membranes feature high stability and an extreme elasticity, as emphasized by the very low values of Young's modulus, varying from 2.08 MPa to 2.6 MPa over the studied thickness range. The extreme elasticity of the membranes stems from the elastomer-like character of the PEG network, consisting of the STAR-PEG cores interconnected by crosslinked PEG chains. This elasticity is only slightly affected by a moderate reduction in the interconnections at a deviation from the standard 1:1 composition of the precursors. However, both the elasticity and stability of the membranes are strongly deteriorated by a strong distortion of the network imposed by electron irradiation of the membranes. In contrast, exposure of the membranes to ultraviolet (UV) light (254 nm) does not affect their elastic properties, supporting the assumption that the only effect of such treatment is the decomposition of the PEG material with subsequent desorption of the released fragments. An analysis of the data allowed for the exclusion of so called "hot electrons" as a possible mechanism behind the modification of the PEG membranes by UV light.

Pharmaceuticals, steroids, personal care products, and disruptive endocrine substances are increasingly being used for healthcare objectives and to improve living conditions, resulting in the widespread presence of micropollutants in various water sources. Traditional water/ sewage and wastewater treatment plants are limited in their ability to cope with with these pollutants, making it challenging to supply safe and clean water for drinking and other domestic purposes. In this review, carbon nanotubes (CNTs) and CNTs related composites/ membranes have been considered suitable for settling this emerging issue. The existence of emerging micropollutants and their deleterious effects on human and animal health are discussed in this review. The efficient removal of micropollutants from different water sources using different types of CNTs (pristine/ functionalized) and CNTs-based composites/ membranes have been reviewed and evaluated. Moreover, fabrication approaches CNTs- based composites/membranes are also presented with their merits and demerits. Lastly, the current barriers and future perspectives are discussed in detail. The present review provides an in-depth understanding of the removal of micropollutants from CNTs and CNTs related composites/ membrane and allows future researchers to resolve the barriers related to their applications at an industrial scale. [Display omitted] • European legislation and legal guidelines on micropollutants discharge into the environment. • Fabrication routes and applications of CNT and CNT-based composites/ membranes. • Challenges and future perspective of CNT- based adsorbents and membranes in water treatment. [ABSTRACT FROM AUTHOR]

The combination of strain and electrostatic engineering in epitaxial heterostructures of ferroelectric oxides offers many possibilities for inducing new phases, complex polar topologies, and enhanced electrical properties. However, the dominant effect of substrate clamping can also limit the electromechanical response and often leaves electrostatics to play a secondary role. Releasing the mechanical constraint imposed by the substrate can not only dramatically alter the balance between elastic and electrostatic forces, enabling them to compete on par with each other, but also activates new mechanical degrees of freedom, such as the macroscopic curvature of the heterostructure. In this work, an electrostatically driven transition from a predominantly out-of-plane polarized to an in-plane polarized state is observed when a PbTiO 3 /SrTiO 3 superlattice with a SrRuO 3 bottom electrode is released from its substrate. In turn, this polarization rotation modifies the lattice parameter mismatch between the superlattice and the thin SrRuO 3 layer, causing the heterostructure to curl up into microtubes. Through a combination of synchrotron-based scanning X-ray diffraction imaging, Raman scattering, piezoresponse force microscopy, and scanning transmission electron microscopy, the crystalline structure and domain patterns of the curved superlattices are investigated, revealing a strong anisotropy in the domain structure and a complex mechanism for strain accommodation., (© 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

The efficiency of CO 2 electroreduction has been largely limited by the activity of the catalysts as well as the three-phase interface. Herein, a multiscale strategy is proposed to synthesize hierarchical nanofibers covered by carbon nanotubes and embedded with cobalt nanoparticles (Co/CNT/HCNF). The confinement effect of carbon nanotubes can restrict the diameter of the cobalt particles down to several nanometers and prevent the easy corrosion of these nanoparticles. The three-dimensional carbon nanofibers, in size range of several hundred nanometers, improve the electrochemically active surface area, facilitate electron transfer, and accelerate CO 2 transportation. These cross-linked carbon nanofibers eventually form a freestanding Co/CNT/HCNF membrane of dozens of square centimeters. Consequently, Co/CNT/HCNF produces CO with 97% faradaic efficiency at only -0.4 V RHE cathode potential in an H-type cell. From the regulation of catalyst nanostructure to the design of macrography devices, Co/CNT/HCNF membrane can be directly used as the gas-diffusion compartment in a flow cell device. Co/CNT/HCNF membrane generates CO with faradaic efficiencies higher than 90% and partial current densities greater than 300 mA cm -2 for at least 100-h stability. This strategy provides a successful example of efficient catalysts for CO 2 electroreduction and also has the feasibility in other self-standing energy conversion devices., (© 2021 Wiley-VCH GmbH.)

Metasurfaces have emerged as a breakthrough platform for manipulating light at the nanoscale and enabling on-demand optical functionalities for next-generation biosensing, imaging, and light-generating photonic devices. However, translating this technology to practical applications requires low-cost and high-throughput fabrication methods. Due to the limited choice of materials with suitable optical properties, it is particularly challenging to produce metasurfaces for the technologically relevant mid-infrared spectral range. These constraints are overcome by realizing functional metasurfaces on almost completely transparent free-standing metal-oxide membranes. A versatile nanofabrication process is developed and implemented for highly efficient dielectric and plasmonic mid-infrared metasurfaces with wafer-scale and complementary metal-oxide-semiconductor (CMOS)-compatible manufacturing techniques. The advantages of this method are revealed by demonstrating highly uniform and functional metasurfaces, including high-Q structures enabling fine spectral selectivity, large-area metalenses with diffraction-limited focusing capabilities, and birefringent metasurfaces providing polarization control at record-high conversion efficiencies.  Aluminum plasmonic devices and their integration into microfluidics for real-time and label-free mid-infrared biosensing of proteins and lipid vesicles are further demonstrated. The versatility of this approach and its compatibility with mass-production processes bring infrared metasurfaces markedly closer to commercial applications, such as thermal imaging, spectroscopy, and biosensing., (© 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

• Free-standing porous membranes are prepared for Li-S electrodes with high areal sulfur loading. • Mo 3 Ni 3 N and Mo 2 C nanoparticles are demonstrated to attract sulfur and soluble intermediate polysulfide species. • Large specific capacity and excellent cycling stability are achieved. Lithium-sulfur batteries are considered as a promising candidate for next-generation energy-storage applications because of its high energy densities. However, the practical utilization of lithium–sulfur batteries is compromised by fast capacity decay, limited sulfur loading and significant polysulfide shuttling. Herein, we designed and prepared a free-standing lithium-sulfur electrode by loading sulfur into a hybrid material (Mo 3 Ni 3 N/Mo 2 C-CBC/S) constructed by growing Mo 3 Ni 3 N/Mo 2 C nanoparticles on carbonized bacterial cellulose film (CBC). High sulfur content up to 70 wt% and high areal sulfur loading of 15.5 mg cm−2 in Mo 3 Ni 3 N/Mo 2 C-CBC/S membrane are achieved. Reversible specific capacities of 1218 and 823 mA h g−1 are delivered for current rates of 0.1 and 1.0 C, respectively. A high capacity over 500 mA h g−1 is retained after 500 cycles at 1.0 C. The superior electrochemical performance of Mo 3 Ni 3 N/Mo 2 C-CBC/S composite is attributed to the unique structure feature and the synergistic effect of the Mo 3 Ni 3 N and Mo 2 C nanoparticles. The Mo 3 Ni 3 N/Mo 2 C component could suppress the dissolution and shuttling of the polysulfides and Mo 2 C could improve the electronic conductivity of the composite, consequently contributing to the excellent electrochemical performance of the composite. [ABSTRACT FROM AUTHOR]

The search for high-capacity, low-cost electrode materials for sodium-ion batteries is a significant challenge in energy research. Among the many potential candidates, layered compounds such as MoS2 have attracted increasing attention. However, such materials have not yet fulfilled their true potential. Here, we show that networks of liquid phase exfoliated MoS2 nanosheets, reinforced with 20 wt % single-wall carbon nanotubes (SWNTs), can be formed into sodium-ion battery electrodes with large gravimetric, volumetric, and areal capacity. The MoS2/SWNT composite films are highly porous, electrically conductive, and mechanically robust due to its percolating carbon nanotube network. When directly employed as the working electrode, they exhibit a specific capacity of >400 mAh/g and volumetric capacity of ∼650 mAh/cm(3). Their mechanical stability allows them to be processed into free-standing films with tunable thickness up to ∼100 μm, corresponding to an areal loading of 15 mg/cm(2). Their high electrical conductivity allows the high volumetric capacity to be retained, even at high thickness, resulting in state-of-the-art areal capacities of >4.0 mAh/cm(2). Such values are competitive with their lithium-ion counterparts.