Framework Composition Research Articles

Machine learning-assisted computational exploration of the optimal loading of IL in IL/COF composites for carbon dioxide capture

The “volumetric loading ratio” is proposed as a descriptor for regulating the IL loading of IL/COF composites. IL and COFs can form CO2favorable “wire-tube” and “wall-arm” type structures in COFs with pore sizes <10 Å and ≥10 Å, respectively.

One-step synthesis of magnetic covalent organic framework composite for the adsorption of marine toxin okadaic acid

One-step synthesis of a crystalline magnetic covalent organic framework composite is reported using a sub-stoichiometric amount of the diamino building block. The composite showed high efficiency for the removal of okadaic acid toxin from seawater.

Covalent connections between metal-organic frameworks and polymers including covalent organic frameworks.

Hybrid composite materials combining metal-organic frameworks (MOFs) and polymers have emerged as a versatile platform for a broad range of applications. The crystalline, porous nature of MOFs and the flexibility and processability of polymers are synergistically integrated in MOF-polymer composite materials. Covalent bonds, which form between two distinct materials, have been extensively studied as a means of creating strong molecular connections to facilitate the dispersion of "hard" MOF particles in "soft" polymers. Numerous organic transformations have been applied to post-synthetically connect MOFs with polymeric species, resulting in a variety of covalently connected MOF-polymer systems with unique properties that are dependent on the characteristics of the MOFs, polymers, and connection modes. In this review, we provide a comprehensive overview of the development and strategies involved in preparing covalently connected MOFs and polymers, including recently developed MOF-covalent organic framework composites. The covalent bonds, grafting strategies, types of MOFs, and polymer backbones are summarized and categorized, along with their respective applications. We highlight how this knowledge can serve as a basis for preparing macromolecular composites with advanced functionality.

TPN-COF@Fe-MIL-100 composite used as an electrochemical aptasensor for detection of trace tetracycline residues.

In this work, a metal-organic framework@covalent organic framework composite (TPN-COF@Fe-MIL-100) was prepared and used as a sensing material to construct an aptasensor for trace detection of tetracycline (TET). The TPN-COF@Fe-MIL-100 integrates a large surface area, porous structure, excellent electrochemical activity, rich chemical functionality, and strong bioaffinity for aptamers, providing abundant active sites to effectively anchor aptamer strands. As a result, the TPN-COF@Fe-MIL-100-based aptasensor shows high sensitivity for detecting TET via specific recognition between aptamer and TET to form G-quadruplex. An ultralow detection limit of 1.227 fg mL-1 is deduced from the electrochemical impedance spectroscopy within a wide linear range of 0.01-10000 pg mL-1 for TET. The TPN-COF@Fe-MIL-100-based aptasensor also exhibits good selectivity, reproducibility, stability, regenerability, and applicability for a real milk sample. Therefore, the TPN-COF@Fe-MIL-100-based aptasensor will be promising for detecting trace harmful antibiotics residues for food safety.

Metal–organic framework composites from a mechanochemical process

This review summarizes the unique advantages and opportunities offered by the mechanochemical process to generate MOF composites.

Progress and opportunities for metal-organic framework composites in electrochemical sensors.

Metal-organic framework composites have the advantages of large surface area, high porosity, strong catalytic efficiency and good stability, which provide a great possibility of finding excellent electrode materials for electrochemical sensors. However, MOF composites still face various challenges and difficulties, which limit their development and application. This paper reviews the application of MOF composites in electrochemical sensors, including MOF/carbon composites, MOF/metal nanoparticle composites, MOF/metal oxide composites and MOF/enzyme composites. In addition, the application challenges of MOF composites in electrochemical sensors are summarized. Finally, the application prospect for MOF composites is considered to promote the synthesis of more MOF composites with excellent properties.

Recent advances in the synthesis and catalytic applications of metal–organic framework/covalent organic framework composites

MOF/COF composites constructed by heterojunction, functionalization, or integration show enhanced performance in photo-, thermo-, and electrocatalysis. This review is informative for rational design and mechanism understanding of MOF/COF catalysts.

Design of enzyme@metal organic framework composites with thermo-responsivity for colourimetric detection of glucose.

Enzyme immobilization on metal-organic frameworks (MOFs) has interested researchers in recent decades due to the outstanding characteristics of MOFs. However, despite some enzyme@MOF composites exhibiting better tolerance, stability and catalysis than free enzymes, boosting the catalytic performance of stimuli-responsive polymer-grafted MOFs composites remains a challenging task. Herein, a glucose oxidase (GOx)-horseradish peroxidase (HRP)@MOF (UiO-66-NH2, U)@polymer composite with tunable catalytic ability was constructed by modification with thermo-responsive poly(N-isopropylacrylamide) (PN) via a surface-selective post-synthetic protocol. Temperature increases changed the PN-based soft armour from a "stretch" to a "coil" conformation on the MOF surface, resulting in the confinement effect and boosting the catalytic performance of the GOx-HRP@U@PN composites. Compared with its maximum catalytic reaction rate at 25 °C, the proposed composites showed 18-fold improvement in catalytic performance at 37 °C. Additionally, a colourimetric method for serum glucose analysis was developed using a GOx-HRP-based catalytic cascade reaction with a linear range from 0.1 to 2.0 mM and a low detection limit of 0.03 mM. Remarkably, the surface PN-shell-based soft armour proved to be the key factor for enhancing the catalytic performance of the as-designed composites. The co-immobilization of GOx-HRP onto the thermo-responsive U@PN surface provides a new approach for the development of highly sensitive colourimetric glucose sensing protocols.

Integrated carbon nanotube and triazine-based covalent organic framework composites for high capacitance performance.

As a rising class of crystallographic organic polymers, covalent-organic frameworks (COFs) have high specific surface areas, ordered pore structures, and designability, which exhibit broad application prospects in the energy storage sector. However, their low electrical conductivity hinders their potential use in supercapacitors. To improve the electrical conductivity, we introduced carboxylated multi-walled carbon nanotubes to obtain a series of carbon nanotube@COF composites by a facile one-pot method, in which 2D TFA-COFs are in situ grown on the surface of carboxylated multi-walled carbon nanotubes. Among them, the CNT@TFA-COF-3 composite exhibits good crystallinity, regular pores, excellent stability and a specific surface area of 1034 m2 g-1. As expected, as a capacitive electrode material, the CNT@TFA-COF composite shows improved electrochemical performance. Notably, the value of specific capacitance of the CNT@TFA-COF-3 composite (338 F g-1) is about 8.5, 4.9, and 7.5 times higher than those of TFA-COFs, CNTs, and the CNT/TFA-COF physically mixed complex at a current density of 1.0 A g-1, respectively. Furthermore, the CNT@TFA-COF-3 supercapacitor exhibits long-term cycle chemical stability and splendid rate capability even after 7000 charge-discharge cycles. The successful preparation of the CNT@TFA-COF-3 composite can provide new ideas for the construction of new COF-based composites and the development of new materials for energy storage.

Three-dimensional graphene/metal-organic framework composites for electrochemical energy storage and conversion.

Three-dimensional graphene (3DG)/metal-organic framework (MOF)-based composites have attracted more and more attention in the field of energy due to their unique hierarchical porous structure and properties. The combination of graphene with MOFs can not only effectively overcome the limitations of poor electrical conductivity and low stability of MOFs, but also prevent the aggregation and reaccumulation between graphene sheets. Moreover, 3DG/MOF composites can also be used as multifunctional precursors with adjustable structures and composition of derivatives, thus expanding their applications in the field of electrochemistry. This feature article elaborates the latest synthesis methods of 3DG/MOF composites and their derivatives, along with their applications in batteries, supercapacitors (SCs) and electrocatalysis. In addition, the current challenges and future prospects of 3DG/MOF-based composites are discussed.

Rapid synthesis of magnetic microspheres and the development of new macro–micro hierarchically porous magnetic framework composites

Highly porous magnetic microspheres are synthesised through a flame spheroidisation process and surface functionalised. Metal–organic frameworks are then grown on the surfaces to produce novel hierarchically porous magnetic framework composites.

Development of core@shell magnetic framework composite for immunoselective detection and capture of Salmonella typhimurium

A Fe3O4/Si@MIL-125 magnetic framework composite is demonstrated for optical detection and simultaneous removal of pathogenic Salmonella typhimurium. The fabricated nanomaterial exhibited promising opto-magnetic properties and stability.

In situ anchoring of MnO nanoparticles into three-dimensional nitrogen-doped porous carbon framework as a stable anode for high-performance lithium storage

Although transition metal oxides have the advantages of large theoretical capacity, low cost and eco-friendliness, their application as anodes for lithium-ion batteries (LIBs) is still limited due to their undesirable electrical conductivity and large volume expansion. Herein, a novel two-step rapid freeze-drying-calcination strategy was applied to prepare highly dispersed nano-MnO-anchored three-dimensional nitrogen-doped porous carbon framework composites (MnO@3D N-PCF). Compared with MnO and undoped MnO@3D PCF, the MnO@3D N-PCF anode exhibits superb cycle stability, remarkable specific capacity and impressive high-rate performance (1037.0 mAh g−1 over 100 cycles at 0.1 A g−1 and 760.9 mAh g−1 over 500 cycles at 5 A g−1), mainly due to its well-designed 3D nanoarchitecture. It is found that 3D nitrogen-doped carbon networks can act as stable conductive bridges to facilitate electron transport and sufficient diffusion channels for Li ions. The MnO nanoparticles obtained by rapid lyophilization and calcination technology are highly dispersed in the porous 3D carbon skeleton, which can buffer volume expansion and preserve the stability of the electrode. It is expected that this simple and green synthesis strategy will open the door for the development of transition metal oxide/carbon three-dimensional nanocomposites with high stability and excellent electrochemical properties.

Overview on recent advances of magnetic metal-organic framework (MMOF) composites in removal of heavy metals from aqueous system.

Developing a novel, simple, and cost-effective analytical technique with high enrichment capacity and selectivity is crucial for environmental monitoring and remediation. Metal-organic frameworks (MOFs) are porous coordination polymers that are self-assembly synthesized from organic linkers and inorganic metal ions/metal clusters. Magnetic metal-organic framework (MMOF) composites are promising candidate among the new-generation sorbent materials available for magnetic solid-phase extraction (MSPE) of environmental contaminants due to their superparamagnetism properties, high crystallinity, permanent porosity, ultrahigh specific surface area, adaptable pore shape/sizes, tunable functionality, designable framework topology, rapid and ultrahigh adsorption capacity, and reusability. In this review, we focus on recent scientific progress in the removal of heavy metal ions present in contaminated aquatic system by using MMOF composites. Different types of MMOFs, their synthetic approaches, and various properties that are harnessed for removal of heavy metal ions from contaminated water are discussed briefly. Adsorption mechanisms involved, adsorption capacity, and regeneration of the MMOF sorbents as well as recovery of heavy metal ions adsorbed that are reported in the last ten years have been discussed in this review. Moreover, particular prospects, challenges, and opportunities in future development of MMOFs towards their greener synthetic approaches for their practical industrial applications have critically been considered in this review.

Dye-encapsulated metal–organic framework composites for highly sensitive and selective sensing of oxytetracycline based on ratiometric fluorescence

Dye-encapsulated metal–organic framework composites for highly sensitive and selective sensing of oxytetracycline based on ratiometric fluorescence

Characteristics of in situ synthesized activated carbon and metal‐organic framework composites for CH4/N2 gas mixture separation

AbstractIn this study, activated carbon and metal‐organic framework composites were synthesized by in situ hydrothermal method, and the surface morphology, physicochemical structure and adsorption performance of the materials were tested. Moreover, the competitive adsorption characteristics of CH4/N2 gas mixture on the materials MIL‐101, DFAC‐MIL‐101 and NMAC‐MIL‐101 were predicted based on the ideal adsorption solution theory (IAST). Results show that the rod‐like fibers formed after doping with activated carbon did not affect the crystal structure of the metal‐organic framework material but caused the unevenness and passivation of the crystal surface, and the crystal size of MIL‐101 was significantly decreased due to which the micropores of the composite material were more developed, while the mesopores and macropores were decreased accordingly. Meanwhile, the micropore size of MIL‐101 and Ac‐MIL‐101 composite materials were mainly distributed around 0.9, 1.2 and 1.7 nm. The adsorption isotherms of these three materials for CH4 and N2 had typical type I characteristics, and the adsorption selectivity S for binary CH4/N2 gas mixture is greater than 2. Doping activated carbon could properly control the structure of MIL‐101 crystals and improved the selectivity effectively, which provides a certain guiding significance for the structure regulation and application of MIL‐101 metal‐organic framework materials. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Constructing Porous Alumina Frameworks by Sintering for Enhanced Thermal Conductivity of Polymer Composites.

Constructing continuous filler networks in a polymer matrix can significantly improve the thermal conductivity of the composite. In this study, we fabricated porous Al2O3 frameworks (f-AO) by decomposing the sacrificial material and sintering to serve as heat conduction pathways in the matrix. Then, epoxy/Al2O3 frameworks (EP/f-AO) composites with excellent thermal conductivity were obtained by vacuum infiltration. The pre-constructed Al2O3 frameworks and sintering reduce interfacial thermal resistance by 1 order of magnitude and result in a dramatically enhanced thermal conductivity of EP/f-AO composites. At the filler content of 49.5 vol %, the thermal conductivity of the EP/f-AO composite is 6.96 W m-1 K-1, which is 4.3 times that of the EP/AO composite (1.61 W m-1 K-1) with randomly dispersed fillers. The heat dissipation capability of the EP/f-AO composites was further confirmed by infrared thermal imaging. This study provides a promising approach for fabricating thermal conductive polymer composites as electronic package materials.

Physical and mechanical properties of pre-bound aggregate composites

New building materials and products in construction and reconstruction, which improve the performance and efficiency characteristics of buildings, reduce material consumption, cost and labor intensity, are always relevant. A promising direction for further development of composite materials is the employment of pre-bound aggregate materials. Their production is a two-stage process, which involves at first creating an optimal aggregate mix and gluing the grains to each other and secondly filling the voids of the obtained aggregate framework with a high-workability matrix. Presented research is an experimental investigation of physical and technical properties of pre-bound aggregate composite materials. Composites with complex binders are also considered in this study. In such cases, the aggregate framework and the grouting matrix were made of binders of different nature, which are incompatible when the components are mixed ordinarily. When studying composites, a complex of physical and mechanical methods was used. Improvement of physical and mechanical properties of framework composites in comparison with composites obtained according to conventional techno- logy has been established. These advantages are identified primarily for such properties as deformability, impact strength, creep.

Environmental and hydrologic controls on sediment and organic carbon export from a subalpine catchment: insights from a time series

Abstract. Studies engaging in tracking headwater carbon signatures downstream remain sparse, despite their importance for constraining transfer and transformation pathways of organic carbon (OC) and developing regional-scale perspectives on mechanisms influencing the balance between remineralization and carbon export. Based on a 40-month time series, we investigate the dependence of hydrology and seasonality on the discharge of sediment and OC in a small (350 km2) Swiss subalpine watershed (Sihl River basin). We analyze concentrations and isotopic compositions (δ13C, F14C) of particulate OC and use dual-isotope mixing and machine learning frameworks to characterize and estimate source contributions, transport pathways, and export fluxes. The majority of transferred OC is sourced from plant biomass and soil material. The relative amount of bedrock-derived (petrogenic) OC, abundant in headwater streams, progressively decreases downstream in response to a lack of source material and efficient overprinting with biospheric OC, illustrating rapid organic matter alteration over short distances. Large variations in OC isotopic compositions observed during baseflow conditions converge and form a homogenous mixture enriched in OC and characterized by higher POC-F14C values following precipitation-driven events. Particulate OC isotopic data and model results suggest that storms facilitate surface runoff and the inundation of riparian zones, resulting in the entrainment of loose plant-derived debris and surficial soil material. Although particle transport in the Sihl River basin is mainly driven by hydrology, subtle changes in bedrock erosivity, slope angle, and floodplain extent likely have profound effects on the POC composition, age, and export yields.

Synthesis of UiO-66 series metal–organic framework composites and the adsorption effect on gallium

It is an urgent problem to alleviate the contradiction between the supply and demand of gallium (Ga) resources and improve the extraction and utilization efficiency of Ga resources. The GO/UiO-66-NH2 composite adsorbent was synthesized by hydrothermal synthesis of graphene oxide (GO) and UiO-66-NH2 series metal–organic skeleton, which was employed for efficient recovery and extraction of Ga in solution. The morphology, structure, elemental composition, and chemical properties of the composite adsorbent were studied by a series of batch experiments, respectively. The effects of the amount of adsorbent, adsorption time, initial concentration, and pH value of the solution on the adsorption effect were investigated. Results found that the adsorption mechanism of Ga by 4-GO/UiO-66-NH2 is mainly ion exchange forming chelate, accompanied by electrostatic interaction. The optimized adsorption conditions for reaching the saturated adsorption capacity of 661.67 mg/g Ga were found to be pH 9 and the temperature 313 K. The results of thermodynamic study pointed out the adsorption of Ga is spontaneous and feasible. The aforementioned results demonstrate that GO/UiO-66-NH2 composite adsorbent has strong adsorption performance and application potential for the recovery and exploitation of Ga, offering practical and theoretical support for the future development and utilization of Ga resources.