Functional covalent organic framework illuminate rapid and efficient capture of Cu (II) and reutilization to reduce fire hazards of epoxy resin

Polymer Encapsulated Framework Materials for Enhanced Gas Storage and Separations

Within the broader field of energy storage, polymer-encapsulated framework (PEF) materials have witnessed remarkable growth in recent years, with transformative implications for diverse applications. This comprehensive review discusses in detail the latest advancements in the design, synthesis, and applications of PEFs in gas storage and separations. Following a thorough survey of existing literature, the article delves into mechanistic considerations and foundational principles governing PEF synthesis. Emphasis is placed on covalent and coordinative covalent grafting methods, physical blending, nonsolvent utilization, and various vapor deposition techniques. The discussion critically evaluates the advantages and disadvantages of these synthesis approaches, considering factors such as grafting density, coating thickness, and other physical properties relevant to processability and stability in comparison to traditional framework materials. Special attention is given to the impact of polymer coatings on gas adsorption analysis. Finally, notable accomplishments and advancements in the PEF field, including mixed matrix membrane (MMM) technology, improvements in framework form factors, and enhanced chemical and mechanical stability are summarized. This review concludes by offering valuable perspective for researchers, highlighting gaps and challenges that confront the current state-of-the-art in PEF materials, paving the way for future innovations that are poised to help address global energy challenges.

Emerging MOFs, COFs, and their derivatives for energy and environmental applications

Traditional fossil fuels significantly contribute to energy supply, economic development, and advancements in science and technology. However, prolonged and extensive use of fossil fuels has resulted in increasingly severe environmental pollution. Consequently, it is imperative to develop new, clean, and pollution-free energy sources with high energy density and versatility as substitutes for conventional fossil fuels, although this remains a considerable challenge. Simultaneously, addressing water pollution is a critical concern. The development, design, and optimization of functional nanomaterials are pivotal to advancing new energy solutions and pollutant remediation. Emerging porous framework materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), recognized as exemplary crystalline porous materials, exhibit potential in energy and environmental applications due to their high specific surface area, adjustable pore sizes and structures, permanent porosity, and customizable functionalities. This work provides a comprehensive and systematic review of the applications of MOFs, COFs, and their derivatives in emerging energy technologies, including the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, lithium-ion batteries, and environmental pollution remediation such as the carbon dioxide reduction reaction and environmental pollution management. In addition, strategies for performance adjustment and the structure-effect relationships of MOFs, COFs, and their derivatives for these applications are explored. Interaction mechanisms are summarized based on experimental discussions, theoretical calculations, and advanced spectroscopy analyses. The challenges, future prospects, and opportunities for tailoring these materials for energy and environmental applications are presented.

Synthesis of MnFe2O4-biochar with surficial grafting hydroxyl for the removal of Cd(II)-Pb(II)-Cu(II) pollutants: Competitive adsorption, application prospects and binding orders of functional groups

A novel biochar material with magnetic modification by MnFe2O4 and surficial hydroxyl grafting (h-MFO-BC) was synthesized for capturing HMs (Cd, Pb and Cu) and their competition in composite systems was investigated. The modification of hydroxyl considerably improved the adsorption capacity of HMs. Chemisorption and monolayer and homogeneous reaction dominated adsorption processes. Moreover, a pronounced competitive adsorption effect between HMs was observed in composite systems. The order of selectivity by h-MFO-BC was Pb > Cu ≫ Cd. The distinction in the adsorption of HMs was related to different adsorption pathways and binding sequences of functional groups. Two-dimensional correlation spectroscopy revealed that Pb and Cu preferred to bind to the active sites (Mn/Fe-OH) on h-MFO-BC surface. Moreover, they could generate hydroxide precipitation more easily, which prevented further adsorption of Cd due to the occupation or coverage of binding sites and electrostatic repulsion. Furthermore, h-MFO-BC could be effectively regenerated and recycled and possessed fascinating performance in HMs removal from real water, indicating its potential for widespread applicability. This work provided a novel composite material for the treatment of HMs in wastewater or selective recovery of Pb and Cu and gave a new perspective on understanding the competition mechanisms between HMs on adsorbents.

Full Spectral Overlap to Enhanced Fluorescence Quenching Ability by Using Covalent Organic Frameworks as a Springboard of Quencher for the Turn-on Fluorescence Immunoassay

According to the fluorescence internal filtering effect (IFE), the more the absorption spectrum of the quencher overlaps with the excitation and emission spectra of the fluorescent substance, the better the quenching effect and, correspondingly, the more significant and sensitive the contrast becomes when the fluorescence is turned on. Thus, in the competitive fluorescence-quenching lateral flow immunoassays (FQ-LFIAs), the fluorescence quencher with an outstanding optical property is of great importance. Herein, gold nanoparticles (AuNPs) and polydopamine (PDA) coengineered covalent organic frameworks (COF/Au@PDA) were synthesized as a fluorescence quencher to increase spectral overlap. Thanks to the excellent visible light absorption of COF with donor-acceptor (D-A) structure, the localized surface plasmon resonance (LSPR) capability of AuNPs, and the broad light absorption of the PDA layer, the COF/Au@PDA exhibits intense absorption and a full spectral overlap toward aggregation-induced emission luminous (AIE) dots. Thereafter, COF/Au@PDA, with its immense potential to completely quench the fluorescence of AIE dots through primary IFE and secondary IFE, was applied to a bimodal LFIA platform for verification with a nitrofurazone metabolite as a model analyte. As expected, the detection sensitivity of the COF/Au@PDA-based FQ-LFIA (turn-on) is improved by 6-fold compared with that of the colorimetric (CM)-LFIA (turn-off). Further, ChatGpt was used to improve the assay accuracy and sensitivity, utilizing its high sensitivity to subtle changes in LFIA signals, especially for weak signals that are indeterminate with the naked eye. This work offers a potential approach for building a high-performance fluorescence quencher in the FQ-LFIA and indicates the potential for the application of artificial intelligence in highly sensitive LFIAs.

Salted Dried Bamboo Shoots-Derived Mesoporous Carbon Inherently Doped with SiC and Nitrogen for Capacitive Deionization

Dried bamboo shoots (DBS) are a natural resource with inherent silica content, which can serve as sacrificial templates for the formation of mesoporous carbon but also promote the generation of silicon carbide (SiC). Building on this, we introduced mesoporous and graphitic carbon/SiC (SiC/BSC) as the CDI electrode for copper ion (Cu2+) removal. Mesoporous carbon electrodes facilitate faster ion transport, diffusion, and electron-transfer pathways. Furthermore, SiC accelerates electron transfer and promotes faradic redox reactions during the charge and discharge processes. Consequently, the synergistic effect of SiC/BSC mesoporous carbon material leads to a promising electrode for Cu2+ capacitive deionization. Leveraging these unique properties, the SiC/BSC electrode material exhibits an outstanding CDI performance of 381.5 mg/g at 1.8 V. This study offers a strategy for the preparation of efficient mesoporous carbon materials as CDI electrodes, specifically tailored for the deionization of Cu2+ ions.

Applications of covalent organic frameworks for the elimination of dyes from wastewater: A state-of-the-arts review

Covalent organic frameworks (COFs) are class of porous coordination polymers made up of organic building blocks joined together by covalent bonding through thermodynamic and controlled reversible polymerization reactions. This review discussed versatile applications of COFs for remediation of wastewater containing dyes, emphasizing the advantages of both pristine and modified materials in adsorption, membrane separation, and advanced oxidations processes. The excellent performance of COFs towards adsorption and membrane filtration has been centered to their higher crystallinity and porosity, exhibiting exceptionally high surface area, pore size and pore volumes. Thus, they provide more active sites for trapping the dye molecules. On one hand, the photocatalytic performance of the COFs was attributed to their semiconducting properties, and when coupled with other functional semiconducting materials, they achieve good mechanical and thermal stabilities, positive light response, and narrow band gap, a typical characteristic of excellent photocatalysts. As such, COFs and their composites have demonstrated excellent potentialities for the elimination of the dyes.

Advanced Covalent Organic Framework-Based Membranes for Recovery of Ionic Resources

Membrane technology has shown a viable potential in conversion of liquid-waste or high-salt streams to fresh waters and resources. However, the non-adjustability pore size of traditional membranes limits the application of ion capture due to their low selectivity for target ions. Recently, covalent organic frameworks (COFs) have become a promising candidate for construction of advanced ion separation membranes for ion resource recovery due to their low density, large surface area, tunable channel structure, and tailored functionality. This tutorial review aims to analyze and summarize the progress in understanding ion capture mechanisms, preparation processes, and applications of COF-based membranes. First, the design principles for target ion selectivity are illustrated in terms of theoretical simulation of ions transport in COFs, and key properties for ion selectivity of COFs and COF-based membranes. Next, the fabrication methods of diverse COF-based membranes are classified into pure COF membranes, COF continuous membranes, and COF mixed matrix membranes. Finally, current applications of COF-based membranes are highlighted: desalination, extraction, removal of toxic metal ions, radionuclides and lithium, and acid recovery. This review presents promising approaches for design, preparation, and application of COF-based membranes in ion selectivity for recovery of ionic resources.

Hierarchical core-shell SiO2@COFs@metallic oxide architecture: An efficient flame retardant and toxic smoke suppression for polystyrene

SiO₂@3COFs@CuO and SiO₂@3COFs@Fe₂O₃ are prepared in this study. Then SiO₂ and its hybrids are incorporated into PS through solution blending method. The thermal stability, mechanical performance, combustion performance and smoke density of PS and its nanocomposite are investigated. The temperature at 5 wt% weight loss and the maximum weight loss rate of PS/SiO₂@3COFs@ Fe₂O₃ (PS 4) under air are 15 and 14 °C higher than that of neat one, respectively. The glass-transition temperature of PS/SiO₂@3COFs (PS 2) is 1.5 °C lower than that of PS, which can conclude that SiO₂@3COFs contributes to impact strength of PS 0. The peak heat release rate (20.8%) and total heat release (14.0%) of PS 2 decreases further compared with that of PS 0. The smoke density of PS 4 is 23.1% lower than that of neat PS. The influence of SiO₂ and its nano-hybrids on the pyrolysis and combustion of PS is investigated. Incorporation of SiO₂ and its nano-hybrids shows little effect on pyrolysis process of PS. However, heat resistance of PS is enhanced obviously and thermal degradation rate of PS is also decreased through incorporation of SiO₂ and its nano-hybrids. The gaseous pyrolysis products (aromatic compounds and alkenyl compounds) of PS and its nanocomposite also decrease.

Structural Characteristics and Environmental Applications of Covalent Organic Frameworks

Covalent organic frameworks (COFs) are emerging crystalline polymeric materials with highly ordered intrinsic and uniform pores. Their synthesis involves reticular chemistry, which offers the freedom of choosing building precursors from a large bank with distinct geometries and functionalities. The pore sizes of COFs, as well as their geometry and functionalities, can be pre-designed, giving them an immense opportunity in various fields. In this mini-review, we will focus on the use of COFs in the removal of environmentally hazardous metal ions and chemicals through adsorption and separation. The review will introduce basic aspects of COFs and their advantages over other purification materials. Various fabrication strategies of COFs will be introduced in relation to the separation field. Finally, the challenges of COFs and their future perspectives in this field will be briefly outlined.