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With the growing interest in fabricating nanofiltration membranes using novel materials and techniques, there is an increasing need to evaluate the practical viability of innovative membranes at the early stages of development. In many materials research laboratories, access to professionally manufactured membrane-evaluation systems may be limited. Here we present a pressure-driven filtration system for evaluation of nanofiltration membranes, which can be constructed from 3D-printed parts and widely available off-the-shelf components at a cost of approximately 60 €. The system uses a stirred cross-flow design capable of circulating the feed solution in the filter cell and maintaining a stable solute concentration during extended filtration experiments—as in conventional cross-flow cells. It is suitable for the filtration of aqueous solutions containing dyes, inorganic salts, and dilute acids. Validation was performed by filtering a 2000 mg L−1 MgSO4 solution through a Veolia RL membrane at 7.6 bar, achieving a 96.5% rejection rate and a permeance of 7.5 L m−2 h−1 bar−1 after 24 h of continuous operation.

Flexible supercapacitors hold promise for applications in wearable electronic devices. However, the challenges of achieving flexibility, miniaturization, and high volumetric capacitance persist. In this work, precise laser etching of cellulose composites, prepared via in-situ growth of conductive metal–organic frameworks (c-MOFs) on cellulose nanofibers (CNF), was employed to fabricate flexible, binder-free, and integrated microsupercapacitors (MSCs). The interfacial synthesis of Ni₃(HITP)₂ (a type of c-MOF) on the surface of CNF yields a continuous and uniform conductive shell, enabling efficient electron transfer along the CNF@c-MOF nanofibers. The interwoven structure of the nanofibers creates a hierarchical porous network with enhanced surface area featuring interconnected porous channels, enabling rapid ion transport. The laser etching technique facilitates one-step production of integrated MSCs with a precisely interdigitated configurations and micron-scale accuracy. The fabricated MSCs demonstrate excellent mechanical stability, with a tensile strength of up to 81.9 MPa, and remarkable flexibility, maintaining consistent electrochemical performance under bending stress. The flexible device, with a thickness of only 45 µm, achieves a high volumetric specific capacitance of 36.7 F cm⁻³ at a current density of 0.17 mA cm⁻² and a specific energy density of 2,497.5 µWh cm⁻³ at a power density of 53.3 mW cm⁻³. This study provides a new strategy for designing flexible, binder-free, integrated MSCs with high capacitances and long cyclic stability, demonstrating significant potential for applications in wearable electronics.

The synthesis of covalent organic frameworks (COFs) has traditionally been carried out under strict solvothermal and anaerobic conditions. The utilization of organic solvents in such reactions not only carries significant costs but also imposes a great burden on the environment. The fabrication of COFs using alternative synthetic pathways has, therefore, seen rapid development in recent years and much attention has been placed on green and sustainable methods in particular. The synthesis of COFs in purely aqueous media, however, remains challenging due to the delicate nature of the chemical reactions and the crystallization process in water. This mini-review discusses different synthetic strategies for the construction of crystalline COFs in aqueous media and offers a perspective on the future development of facile COF synthesis in ambient conditions.

Covalent organic framework (COF) membranes hold significant promise for applications in separation, catalysis, and energy conversion; however, their industrial adoption has been hindered by the lack of scalable and efficient fabrication methods. Here, we present a fast, versatile, and broadly applicable strategy for fabricating free-standing and flexible COF membranes by casting precursor suspensions, followed by heat treatment under controlled humidity. This approach enables the fabrication of COF membranes with lateral dimensions up to several square decimeters and thicknesses that are tunable down to submicron levels within 1 h. It demonstrates remarkable versatility for producing a family of ketoenamine-linked COF membranes through the condensation of 1,3,5-triformylphloroglucinol with various amine monomers differing in length, side groups, and geometry. The resulting crack-free COF membranes exhibit high mechanical strength, with ultimate tensile strength up to 60 MPa and Young’s modulus up to 1.7 GPa, as well as exceptionally high porosity, with Brunauer–Emmett–Teller (BET) surface areas reaching up to 2226 m2 g–1. More importantly, the morphology, porosity, and crystallinity of the membranes can be finely tuned by modulating the heating conditions. The membranes with optimized microstructures demonstrate excellent separation performance, achieving over 99% rejection in nanofiltration of aqueous dye solutions, and a separation factor of 11 with an H2 permeance of 2857 GPU in H2/CO2 gas separation. This approach provides a scalable and effective pathway toward large-scale COF membrane manufacturing for advanced molecular separations and other membrane-based technologies.

Wearable electronics are some of the most promising technologies with the potential to transform many aspects of human life such as smart healthcare and intelligent communication. The design of self-powered fabrics with the ability to efficiently harvest energy from the ambient environment would not only be beneficial for their integration with textiles, but would also reduce the environmental impact of wearable technologies by eliminating their need for disposable batteries. Herein, inspired by classical Archimedean spirals, we report a metastructured fiber fabricated by scrolling followed by cold drawing of a bilayer thin film of an MXene and a solid polymer electrolyte. The obtained composite fibers with a typical spiral metastructure (SMFs) exhibit high efficiency for dispersing external stress, resulting in simultaneously high specific mechanical strength and toughness. Furthermore, the alternating layers of the MXene and polymer electrolyte form a unique, tandem ionic–electronic coupling device, enabling SMFs to generate electricity from diverse environmental parameters, such as mechanical vibrations, moisture gradients, and temperature differences. This work presents a design rule for assembling planar architectures into robust fibrous metastructures, and introduces the concept of ionic–electronic coupling fibers for efficient multimodal energy harvesting, which have great potential in the field of self-powered wearable electronics.

Porous organic polymers (POPs) have shown significant potential for CO₂ capture and utilization due to their high surface areas, tunable porosity, high stability, and ease of modification. Developing POPs for CO₂ capture and catalytic conversion offers a viable solution to rising CO₂ emissions. This study presents POPs composed of pyridine units, serving as dual functional materials that act as sorbents for CO₂ capture and as substrates supporting silver chalcogenolate clusters (SCCs) for catalytic CO₂ conversion. The scalable and cost-effective synthesis of these POPs enabled the design of pilot-scale breakthrough apparatus with two parallel POP sorbent beds for continuous CO₂ capture from simulated flue gas, achieving a high working capacity of 20 L_{flue gas} kg_POP⁻¹ h⁻¹ for flue gas separation. Given the practical feasibility of using POPs for CO₂ capture and the high catalytic activity of POPs loaded with SCCs in CO₂ cycloaddition, a sequential process that integrates capturing CO₂ from simulated flue gas and directly converting the captured CO₂ into oxazolidinone achieves a high space–time yield of up to 9.6 g L_POP⁻¹ day⁻¹ in continuous operation. This study provides a viable strategy for CO₂ capture and utilization using cost-effective, dual-functional porous materials.

Covalent organic frameworks (COFs) are usually synthesized under solvothermal conditions that require the use of toxic organic solvents, high reaction temperatures, and complicated procedures. Additionally, their insolubility and infusibility present substantial challenges in the processing of COFs. Herein, we report a facile, green approach for the synthesis of imine-linked COFs in an aqueous solution at room temperature. The key behind the synthesis is the regulation of the reaction rate. The preactivation of aldehyde monomers using acetic acid significantly enhances their reactivity in aqueous solutions. Meanwhile, the still somewhat lower imine formation rate and higher imine breaking rates in aqueous solution, in contrast to conventional solvothermal synthesis, allow for the modulation of the reaction equilibrium and the crystallization of the products. As a result, highly crystalline COFs with large surface areas can be formed in relatively high yields in a few minutes. In total, 16 COFs are successfully synthesized from monomers with different molecular sizes, geometries, pendant groups, and core structures, demonstrating the versatility of this approach. Notably, this method works well on the gram scale synthesis of COFs. Furthermore, the aqueous synthesis facilitates the interfacial growth of COF nanolayers on the surface of cellulose nanofibers (CNFs). The resulting CNF@COF hybrid nanofibers can be easily processed into freestanding nanopapers, demonstrating high efficiency in removing trace amounts of antibiotics from wastewater. This study provides a route to the green synthesis and processing of various COFs, paving the way for practical applications in diverse fields.