Hybrid Metal Organic Frameworks Research Articles

Modified metal–organic frameworks for sonophotocatalytic elimination of wastewater pollutants

In recent decades, people have witnessed a rapid development of society, accompanied by the increase sharply of numerous organic/inorganic contaminants from industrial effluents. The high toxicity of pollutants has led to long‐term risk to human health. To connect with environment‐friendly green chemistry and sustainable development, photocatalysis technology has emerged. Metal–organic framework (MOF)‐based photocatalysts performed high efficiency for the elimination of wastewater pollutants. Nevertheless, the large band gap energy and high recombination rate of photogenerated electron–hole pair decrease the catalytic efficiency. Sonochemistry is regarded as a safe, highly efficient, clean, and eco‐friendly technology, which has aroused a lot of interest in the treatment of wastewater. The cavitation effect induced by ultrasonic waves promotes the generation of additional active radicals. The ultrasonic oscillation facilitates cleaning the surface of catalysts, dispersing catalyst particles, and increasing proton transport. Therefore, photocatalysis coupling with ultrasonic waves, known as sonophotocatalysis (SPC), is a promising means for enhancing the overall performance of wastewater treatments. This review discusses the recent advancements of hybrid MOF‐based photocatalysts driving the wastewater treatments in SPC system. The catalytic performance of hybrid MOF is discussed in the SPC process. The inner properties of phases in hybrid MOF such as the location of redox potential and transfer direction of electrons and energy after hybridization are elucidated. Additionally, the review discusses the existing challenges and obstacles of MOF‐based SPC system and proposes feasible improvements to meet the future requirements of practical applications.

Microwave-Enabled Fast Preparation of a Metal-Organic Framework Hybrid Membrane for Filtration-Enhanced Simultaneous Separation and Detection of Aflatoxin B1.

Mycotoxin contamination in food and the environment seriously harms human health. Sensitive and timely detection of mycotoxins is crucial. Here, we report a dual-functional hybrid membrane with absorptivity and responsiveness for fluorescent-quantitative detection of mycotoxin aflatoxin B1 (AFB1). A biomineralization-inspired and microwave-accelerated fabrication method was established to prepare a hybrid membrane with a metal-organic framework (MOF) loaded in high density. The MOF presented high efficiency in capturing AFB1 and showed fluorescence intensity alteration simultaneously, enabling a dual adsorption-response mode. Deriving from the inherent porous structure of the hybrid membrane and the absorptive/responsive ability of the loaded MOF, a filtration-enhanced detection mode was elaborated to provide a 1.67-fold signal increase compared with the conventional soaking method. Therefore, the hybrid membrane exhibited a rapid response time of 10 min and a low detection limit of 0.757 ng mL-1, superior to most analogues in rapidity and sensitivity. The hybrid membrane also presented superior specificity, reproducibility, and anti-interference ability and even performed well in extreme environments such as strong acid or alkaline, satisfying the practical requirements for facile and in-field detection. Therefore, the membrane had strong applicability in chicken feed samples, with a detection recovery between 70.6% and 101%. The hybrid membrane should have significant prospects in the rapid and in-field inspection of mycotoxins for agriculture and food.

Metal-organic framework/MXene nanohybrid composites as an emerging electrochemical sensing platform for food safety and biomedical monitoring: From synthesis to application

Metal-organic frameworks (MOFs) are created through the self-assembly process of metal ions or clusters with organic linkers. These materials have attracted important interest owing to their advantageous features, comprising abundant pore structures, ultrahigh porosity, and well-exposed active sites. However, some traditional MOFs have limitations in terms of low stability and conductivity. Despite significant endeavors to enhance the stability of MOF materials, limited advancement has prompted researchers to concentrate on the development of hybrid materials. MXenes, a group of 2D transition-metal compounds comprising nitrides, carbides, and carbonitrides, are recognized for their diverse composition and their ability to form various buildings with rich surface chemistry. The hybridization of MOFs with functional MXene layered could be advantageous if the host structure offers suitable interactions to enhance and stabilize the desired features. Current research has concentrated on incorporating MXenes and MOFs to generate nanohybrid materials with boosted electrochemical features, thus broadening the scope for new applications. This review explores potential design approaches for MXene@MOF nanohybrids, the tunable characteristics of the resulting hybrids, and their use in electrochemical sensing platforms for food safety and biomedical monitoring. Finally, the authors discuss the challenges and future opportunities of MOF@MXene-derived nanocomposites.

Achieving a balance between permeability and selectivity in a ZIF-8-matrix nanocomposite membrane for desalination

Hybrid metal–organic framework (MOF) polymer membranes are promising for addressing the permeability-selectivity tradeoff in membrane applications. The key challenges for achieving high-efficiency separation performance have been identified as increasing the MOF loading while maintaining interfacial compatibility with polymeric matrices. Herein, a novel design of ZIF-8 matrix nanocomposite membrane, with ZIF-8 nanoparticles (NPs) serving as the main matrix, was prepared by functionalizing the external surface of zeolitic imidazolate framework-8 (ZIF-8) NPs with polyethyleneimine and subsequent crosslinking into the selective layer using trimesoyl chloride as a crosslinking agent via confined interfacial polymerization. The content of ZIF-8 NPs in the selective layer was up to about 70 wt%, resulting in superior permeability (＞ 43.6 LMH bar−1) for desalination due to the large number of transport channels, which was several folds as compared to most of the reported membranes. Meanwhile, a reasonably high Na2SO4 rejection (∼95.1 %) was maintained as the polyamide fragments formed during interfacial polymerization, which filled defects among the ZIF-8 NPs. Overall, such strategy paves the way for the design of efficient MOF-based membranes for balancing between permeability and selectivity in desalination.

Cyclodextrin-metal-organic framework (CD-MOF)/ organic-inorganic hybrid composite as a potential material for drug delivery devices

Metal-organic frameworks (MOFs) constitute a distinctive class of materials composed of metal ions or clusters intricately linked by organic ligands. Among MOFs, γ-cyclodextrin- based MOFs (γ-CD-MOFs) have attracted significant attention for their potential in edible, non-toxic, and renewable applications. This study introduces a facile and environmentally friendly method for synthesizing γ-CD-MOFs, integrated with a ureasyl-polyether film to develop a cutaneous patch exhibiting a unique release profile. This system's physicochemical properties, encapsulation, and release kinetics were rigorously evaluated using Ibuprofen as a model anti-inflammatory drug. The resulting films, integrated with γ-CD-MOFs, exhibited an impressive encapsulation efficiency exceeding 80%, and a controlled release effect. Notably, the system demonstrated superior ability in sustaining Ibuprofen release, indicating a synergistic combination of multiple mechanisms, including drug diffusion and erosion of metal-organic frameworks. The comprehensive findings underscore the potential of these systems as effective topical drug-delivery platforms, meeting the stringent criteria of releasing less than 10% of the payload within 12 hours. This study emphasizes the crucial role of rational MOF and organic-inorganic hybrid selection, shedding light on the intricate interplay of chemical parameters among MOF, polymer, and drug, which significantly influence drug adsorption and release dynamics. The outcomes presented herein contribute to advancing our understanding of MOF-based drug delivery systems and highlight their promising future applications in pharmaceutical research.

Assembly of Amorphizing Porous Bimetallic Metal‐Organic Frameworks Spheres with Zn─O─Fe Cluster and Coordination Deficiency via Ligand Competition for Efficient Electro‐Fenton Catalysis

AbstractElectro‐Fenton process stands out as a highly promising approach for generating reactive oxygen‐containing radicals to address the escalating issue of environmental pollution. However, the long‐term goal of application necessitates ongoing pursuit of high‐quality catalysts with both sufficient activity and stability. Herein, a general route is reported for large‐scale synthesis of amorphizing porous bimetallic metal‐organic framework (MOF) spheres with Zn─O─Fe structure and coordination deficiency through facile and low‐cost synthesis of ligand competition. Assisted by a coordination modulator, deprotonation of terephthalic acid is accelerated and rapid synthesis of amorphous bimetallic MOF spheres is successfully achieved at room temperature. As inactive metal Zn is introduced into metal clusters of MOFs, the cycling efficiency of Fe3+/Fe2+ is improved and a secondary building unit of Zn─O─Fe is constructed, greatly accelerating electron conduction rate. Compared to crystalline spindle cMIL‐88B(Fe2Zn) by traditional solvothermal route, amorphous aMIL‐88B(Fe2Zn) has a unique spherical porous structure with larger surface area, higher conductivity, and more exposed active sites. Endowed with unique textural and surface chemistry, aMIL‐88B(Fe2Zn) exhibits superior catalytic activity in the degradation of refractory organic pollutants. The progress offers a feasible way to rational design of iron‐based hybrid MOF materials with tunable structures and enhance properties for various applications.

Graphene conductance modulation through controlled molecular release in a hybrid coordination polymer/graphene field-effect transistor

Coordination polymers, including metal-organic frameworks (MOFs), present a wide range of functionalities ranging from sensing to energy storage. Despite this, many coordination polymers are typically insulating which prevents their implementation into nanoscale electronic devices. Besides, the hybridization of MOFs with other conducting materials, like graphene, is rather unexplored. Here we introduce the grafting of a soft non-porous coordination polymer, the 1·2CH3CN, on a single-layer graphene to form a hybrid 1·2CH3CN/graphene field effect transistor. Electron transport measurements show that the sharp structural transformations in 1·2CH3CN, triggered at two specific temperatures, are detected in graphene as two sharp increments in the electrical current. Gate spectroscopy measurements show that the origin of the electrical modulation is an abrupt p-doping due to the sudden release of acetonitrile right at the structural transition temperatures. Reciprocally, the sensitivity of graphene to external perturbations allows to detect additional transformations in the coordination polymer not observed in direct transport measurements across crystals. Finally, the results have been reproduced in in-situ grown 1·2CH3CN nanoscale films on CVDG FETs. This simple method optimizes the contact area between graphene and 1·2CH3CN and facilitates the integration of coordination polymers with van der Waals materials and electronic devices. Further, a selective doping at specific temperatures could be obtained by modifying the nature of the interstitial molecule in 1.

Universal Strategy for Metal-Organic Framework Growth: From Cascading-Functional Films to MOF-on-MOFs.

Transformation of metal-organic framework (MOF) particles into thin films is urgently needed for the persistent development of well-applicable devices, and recently emerging functional-integrated hybrid frameworks. Although some flexible polymers and exclusive modification approaches have been proposed, the additive-free and widely applicable strategy has not been reported, hampering the deep investigation of the structure-performance relationship. A universal strategy for the in situ growth of large-area and continuous MOF films with controllable microstructures is introduced, through the modification of multi-scale and multi-structure substrates with poly(4-vinylpyridine) as the anchor to capture metal ions via Coulomb attraction. Based on the clarified structure-adsorption-separation mechanisms, the customized devices fabricated by in situ growth can achieve highly selective adsorption and excellently synergetic separation of various industrially relevant isomers. In addition, this strategy is also feasible for the construction of MOF-on-MOFs with varied lattice parameters. This strategy is easy to implement and will be widely applicable to the surface growth of diverse MOFs on desired substrates, and provides a new concept for developing hybrid MOFs integrating with customized functionalities.

In-situ construction of Ti3C2TX/Ni-HHTP heterostructure as anode for lithium-ion batteries

Pursuing anode materials with high specific capacity and long cycle stability is critical for advanced lithium-ion batteries (LIBs). Metal-organic frameworks (MOFs) with high specific surface area, regular pore channels, and multiple active sites are promising anode materials for LIBs. However, the poor electronic conductivity limits their application in LIBs. Thus, introducing some conducting materials is necessary. MXene, known for its excellent electronic conductivity in electrochemical energy storage systems, is an ideal candidate. Herein, a heterostructure composite material (Ti3C2TX/Ni-HHTP) that combines the advantages of both MOFs and MXene has been synthesized via an in-situ growth method, the composite exhibits regular pore channels, enhanced electronic conductivity, and excellent stability. When it is used as an anode material in LIBs, the composite presents satisfying rate performance and cycling stability. The initial discharge capacity of the Ti3C2TX/Ni-HHTP electrode exhibits 424.4 mA h g−1 at 0.5 A g−1 and remains at 390.2 mA h g−1 after 800 cycles with a capacity retention rate of 92.0%. This design strategy provides valuable insights into constructing MOF hybrid materials with enhanced electronic conductivity for various electrochemical applications.

Enhanced simultaneous voltammetric detection of dopamine and uric acid using Au@Ni‐metal–organic framework‐modified electrode

A novel conductive Ni‐based metal–organic framework (MOF) decorated with Au nanoparticles (AuNPs; Au@Ni‐MOF) was developed and used as a drop‐cast thin‐film electrode to individually and simultaneously quantify dopamine (DA) and uric acid (UA). The Ni‐MOF composite was synthesized using an in situ growth strategy involving the growth of [Ni3(BTC)2(H2O)6]n (BTC = 1,3,5‐benzenetricarboxylate) with coordinatively unsaturated Ni (II) sites. The Ni‐MOF powder was then mixed with a AuNP solution to produce a Au@Ni‐MOF hybrid material. The synthesized Au@Ni‐MOF hybrid material was employed as a surface modifier for a screen‐printed carbon electrode, and its efficacy for the detection of DA and UA was assessed using differential pulse voltammetry (DPV) and cyclic voltammetry. The developed sensor exhibited remarkable sensitivity, achieving low detection limits of approximately 0.027 and 0.028 μM (S/N = 3) in the simultaneous quantification of DA and UA, respectively. The sensor exhibited an extensive linear range of 0.5 μM to 1 mM, coupled with excellent sensitivities for DA and UA of 1.43 and 1.35 μA μM−1 cm−2, respectively. Furthermore, the sensor performance in human serum and urine samples was successfully validated using DPV, which revealed outstanding recovery rates of 93.8–105.0% with a minimal relative standard deviation below 3%. Moreover, the synthesized Au@Ni‐MOF composite exhibited exceptional dispersion stability, high sensitivity, and remarkable selectivity, which were attributed to the well‐arranged combination of AuNPs and Ni‐MOFs, enabling its use in non‐enzymatic sensing applications targeting DA and UA.

Sunlight assisted highly efficient desorption of ammonia by redox graphene hybrid metal–organic framework photothermal conversion adsorbents

The capture, storage and release of NH3 play a pivotal role in sustainable energy applications. However, to simultaneously achieve high adsorption capacity and low energy desorption remains a challenge. In this work, a novel class of hybrid materials with photothermal conversion performance have been developed by doping redox graphene and metal–organic framework of MOF-303(Al). It is found that the optimized rGO@MOF-303(Al)-8% exhibits high NH3 uptake (17.0 mmol g−1) at 25.0 °C and 1.0 bar and exceptional photothermal conversion performance. Under the irradiation of simulated sunlight, its temperature can be raised to about 75 °C in 10 min. Even under direct natural sunlight irradiation, a stable equilibrium temperature of 53 °C may be achieved. Based on this excellent photothermal conversion performance, we investigated the desorption behavior of ammonia under visible light irradiation for the first time. We found that due to the breakdown of hydrogen bonds of NH3 and N-N, N–H sites of rGO@MOF-303(Al)-8% caused by the rapid rise of temperature, approximately 68% of NH3 could be effectively desorbed in 2-hour irradiation under ambient conditions. In addition, the optimized adsorbent demonstrated remarkable cycling stability. After undergoing 10 cycles, high adsorption capacity and efficient light-induced desorption of NH3 were still maintained Thus, the present study provides a novel concept for high-capacity adsorption and low-energy desorption of NH3 and other industrial gases.

Graphene and metal-organic framework hybrids for high-performance sensors for lung cancer biomarker detection supported by machine learning augmentation.

Conventional diagnostic methods for lung cancer, based on breath analysis using gas chromatography and mass spectrometry, have limitations for fast screening due to their limited availability, operational complexity, and high cost. As potential replacement, among several low-cost and portable methods, chemoresistive sensors for the detection of volatile organic compounds (VOCs) that represent biomarkers of lung cancer were explored as promising solutions, which unfortunately still face challenges. To address the key problems of these sensors, such as low sensitivity, high response time, and poor selectivity, this study presents the design of new chemoresistive sensors based on hybridised porous zeolitic imidazolate (ZIF-8) based metal-organic frameworks (MOFs) and laser-scribed graphene (LSG) structures, inspired by the architecture of the human lung. The sensing performance of the fabricated ZIF-8@LSG hybrid sensors was characterised using four dominant VOC biomarkers, including acetone, ethanol, methanol, and formaldehyde, which are identified as metabolomic signatures in lung cancer patients' exhaled breath. The results using simulated breath samples showed that the sensors exhibited excellent performance for a set of these biomarkers, including fast response (2-3 seconds), a wide detection range (0.8 ppm to 50 ppm), a low detection limit (0.8 ppm), and high selectivity, all obtained at room temperature. Intelligent machine learning (ML) recognition using the multilayer perceptron (MLP)-based classification algorithm was further employed to enhance the capability of these sensors, achieving an exceptional accuracy (approximately 96.5%) for the four targeted VOCs over the tested range (0.8-10 ppm). The developed hybridised nanomaterials, combined with the ML methodology, showcase robust identification of lung cancer biomarkers in simulated breath samples containing multiple biomarkers and a promising solution for their further improvements toward practical applications.

Modification sub-nano Zn-Co Metal-Organic framework for electrochemical detection of neurotransmitter

We developed a novel platform that was constructed using an in-situ technique to simultaneously synthesize sub-nano Zn-Co on the metal–organic framework (MOF) with a dodecahedron size of 150 nm. The hybridization structure of sub-nano Zn-Co MOF has been demonstrated through shifts of diffraction peaks (XRD patterns) and shake-up satellite peaks, shifting negativity of metallic Co (XPS spectra). The electrochemical dopamine (DA) sensing mechanism was thoroughly analyzed. The sub-nano Zn-Co MOF hybrid material has shown excellent electrochemical results in detecting DA detection at extremely low concentrations. Results from DPV showed that the Zn-Co MOF/GCE has a linear range of 0.01–300 µM of DA and a limit of detection of 6.72 nM. The interference experiments of neurotransmitters (UA, GABA, AA, Gly, Ser) demonstrated not much effect on amperometry changes of DA. Especially, sub-nano Zn-Co MOF/GCE electrode indicated good results in the serum samples, high reproducibility, and can practical application. With advantages including a simple, environmentally friendly, non-enzymatic production process, high selectivity, and reproducible outcomes, DA-detecting sub-nano Zn-Co MOF that has been developed can be used for the initial diagnosis of neurological disorders, the functional evaluation of dopaminergic neurons, chemicals or drugs on human neuronal cells.

Synthesis of metal-organic framework hybrid nanocomposites based on MOFs@C3N4 with high selective separation ability for luteolin

Complex substrates found in certain extracts-particularly those containing high phenolic compounds with significant medicinal value-pose considerable challenges to developing molecularly imprinted membranes (MIMs) with specific recognition abilities. In this study, UiO-66-NH2, a metal–organic structure (MOF), was chosen as an optimizer to enhance the basic support material C3N4. A composite imprinted membrane based on MOFs was then prepared for the targeted adsorption of luteolin (LTL). This not only increases the surface area and pore capacity of the composite membranes, but also ensures unprecedented control over the membranes structure and good stability. To maximize the proportion of imprinted sites, we utilize an advanced boron affinity sol–gel imprinting technique that capitalizes on the exceptional response of the bifunctional monomer. By finely manipulating the imprinting process, controlled distribution of imprinted sites was achieved. Furthermore, the incorporation of Ag nanoparticles into the composite matrix of MIMs enhances selectivity and efficiency due to their plasmonic properties and high affinity for phenolic compounds, providing increased adsorption surface area and additional binding sites. The results showed satisfactory rebinding ability (56.25 mg g−1) and superselective (βAG/LTL = 4.43 and βCT/LTL = 8.49). It was worth noting that incorporating Ag nanoparticles into composite MIMs for the selective adsorption of LTL demonstrates significant potential. This includes enhanced selectivity, efficiency, and hydrophilicity of the membrane surface. Thus, enhanced hydrophilicity can establish stronger non-covalent interactions, namely hydrogen bonding and van der waals forces, with the target molecules, thereby significantly improving the adsorption capacity of the MIMs. The feasibility of this method was demonstrated via in-situ infrared analysis of the chemical structure changes before and after adsorption.

Accelerating Uranium Extraction from Water via Synergy of Adsorption and Filtration by MOF Hybrid Membrane

AbstractIn this paper, novel UiO‐66‐AO‐based adsorption‐filtration hybrid membranes (UAMs) are prepared via an irradiation‐mediated growth strategy to simultaneously improve water flux and accelerate uranium extraction from water resources. The UAM shows an equilibrium adsorption that is four times faster than UiO‐66‐AO powder and an adsorption capacity that is over two times higher. UAM also achieves a record synergy of high flux and high uranium removal ratio from simulated seawater (1358.8 L m−2 h−1, 84.5%) by one‐time filtration under ambient temperature and pressure (the adsorption is 1.83 mg g−1 in 90 min). The excellent uranium extraction performance is attributed to the unique UAM structure, in which water flows through the channels of thin metal‐organic framework (MOF) film without blocking by substrate leading to the high flux during filtration, and the full contact of uranium with abundant exposed active sites promotes the adsorption. This work will be conducive to overcoming the bottleneck problems of uranium extraction from water resources.

Block Copolymer‐Stabilized Metal–Organic Framework Hybrids Loading Pd Nanoparticles Enable Tumor Remission Through Near‐Infrared Photothermal Therapy

Metal–organic frameworks (MOFs), such as the magnetic resonance imaging‐fit MIL‐100 based on Fe, are gaining significant attention as versatile theranostics with high‐loading capability. Moreover, as MOFs can be engineered to target tumors, there is much interest in applying them for precise pin‐point treatment of cancer. Herein, Pd nanoparticles within MIL‐100(Fe) are generated to create MOFs with remarkable photothermal conversion properties for cancer therapy. The Pd‐loaded MIL‐100(Fe) (Pd@MIL‐100(Fe)) are stabilized with biocompatible block copolymers to generate MOFs with PEGylated surfaces. This is achieved by directly mixing poly(ethylene glycol)‐poly(L‐aspartic acid) (PEG‐p(Asp)) or dopamine‐modified PEG‐p(Asp) (PEG‐p(Asp‐Dopa)) block copolymers with the MOFs in aqueous conditions. The resulting block copolymer‐stabilized MOF hybrids are stable in physiological conditions. Particularly, the Pd@MIL‐100(Fe)/PEG‐p(Asp‐Dopa) hybrids show enhanced blood circulation and increased accumulation in B16F10 melanoma. Furthermore, when irradiated with 808 nm light, the Pd@MIL‐100(Fe)/PEG‐p(Asp‐Dopa) hybrids rapidly increase the temperature to 50 °C, enabling tumor remission. The surface‐stabilized Pd@MIL‐100(Fe)/polymer hybrids open viable opportunities for innovating MOF/polymer hybrid‐based approaches for drug delivery.

Semiconductive (Cu–S)n Metal–Organic Frameworks Hybrid Polyaniline Nanocomposites as Hydrogen Sulfide Gas Sensor

A semiconductive (Cu–S)n metal–organic framework (MOF) incorporated polyaniline (PANI) nanocomposite was applied for hydrogen sulfide (H2S) gas sensing. The (Cu–S)n MOF nanosheets were successfully synthesized using a one-pot reflux method. First, fiber-like (Cu–S)n MOF/ PANI nanocomposites were prepared through an in situ oxidative polymerization. As evaluated by field-emission transmission electron microscopy (FE-TEM), the nanosized spherical (Cu–S)n MOF particles were well-distributed in the fiber matrix. Then, the nanocomposite was spin-coated onto an interdigitated electrode (IDE) for H2S gas sensing, displaying high sensitivity, selectivity, repeatability, and stability similar to pure PANI. As a result, 3wt% (Cu–S)n MOF/ PANI nanocomposite showed the best performance for H2S detection. The mechanism for improving H2S sensing performance might be attributed to the conductive composite networks' significantly enhanced conductivity and increased doping sites of the (Cu–S)n MOF. In addition, the energy band gaps of PANI-based nanocomposites were optimized by the incorporated (Cu–S)n MOF, indicating the successful hybridization of energy levels between inorganic MOF and organic PANI. This study first demonstrates semiconductive MOF-PANI-based nanocomposites for H2S gas sensing.

Hierarchical Amino-Functionalized Ionic Liquids@MOF Composite Gel for Catalytic Conversion of CO2.

Hybridization of metal-organic frameworks (MOFs) and homogeneous ionic liquids (ILs) endows the heterogeneous composite with high porosity and accessible multiple active sites (e.g., acidic or basic sites), which exhibits great potential in CO2 capture and conversion. Nevertheless, the majority of MOF composites are synthesized as powders, significantly restricting their practical applications due to inherent problems such as poor handling properties, high pressure drops, and mechanical instability. Thus, it is crucial to shape MOF composites into various monoliths that allow efficient processing, especially for industrial purposes. In this work, a hierarchical ILs@nanoMOF composite gel (H-IL@UiO-66-gel) featuring both intraparticle micropores and interparticle mesopores and multiple active sites was successfully fabricated by a two-step approach. Benefiting from the integrated advantages of the hierarchically porous MOF for enhanced mass transfer and affinity of ILs for activating CO2 molecules, the resultant H-IL@UiO-66-gel exhibits excellent uptake of macromolecules and catalytic activity toward CO2 cycloaddition with epoxides under moderate conditions, far beyond the traditional microporous IL@UiO-66-gel and unfunctionalized H-UiO-66-gel. Furthermore, the H-IL@UiO-66 composite monolith can be effortlessly separated and reused at least three times without depletion of catalytic activity. It is believed that this fabrication method for the shaping of MOF composites is highly versatile and can be extended to other types of MOFs for various application fields.

A series of formic acid MOFs/polylactic acid blending composites with the improved dielectric performance in Co(II) systems

In order to improve the limited compatibility of existing polymer/ceramic dielectric composites and further enhance the energy storage density, MOF/polymer composite dielectrics have been explored, which exhibit good compatibility to the polymer matrix from abundant organic groups of the inorganic–organic hybrid metal-organic framework (MOF) fillers. However, they still lack a clear composition–structure–property rule, and the precise design of MOF fillers and polymer matrix becomes a prominent problem in these composites due to the diversity of the metal ions and the organic groups. Thus, in this paper, we present a series of formic acid MOFs/polylactic acid dielectric composites in which ferroelectric formic acid MOFs, namely PDLLA/[NH[Formula: see text](CH[Formula: see text])[Formula: see text]NH[Formula: see text]][M[Formula: see text](HCOO)[Formula: see text]][Formula: see text] and PDLLA/[CH[Formula: see text]NH[Formula: see text]][M[Formula: see text](HCOO)[Formula: see text]][Formula: see text], in which the formic acid MOFs are with different structures and different metal ions as fillers, including [NH3(CH[Formula: see text]NH3][MII(HCOO)3]2 (namely MOF–Co (M [Formula: see text] Co), MOF–Mg(M [Formula: see text] Mg), MOF–Mn (M [Formula: see text] Mn), with 1, 4-butanediamine ion as guest) and [CH3NH3][M[Formula: see text](HCOO)3]2 (namely MOF–Co[Formula: see text] (M = Co), MOF–Ni[Formula: see text] (Ni), with methylamine ion as guest). The composition and morphology of composite films were characterized by XRD, IR, SEM, DSC and UV, respectively, while the dielectric characterizations of the composites including the dielectric permittivity, the dielectric loss, the breakdown field strength and the energy density were also performed. The composition–structure–property relationships were also investigated including the influence of MOF content and MOF category. With the introduction of MOFs, the dielectric constant of the polylactic acid substrate was improved slightly while the breakdown field strength can be improved in some systems. Interestingly, the Co(II)-containing formic acid MOF has advantages over other formic acid MOFs with similar structure for the enhancement of the dielectric constant and breakdown field strength. Also, in some composite films with methylamine ion guest MOF fillers and low-MOF content (MOF–Co[Formula: see text] (1 vol.%) and MOF–Ni[Formula: see text] (1 vol.%)), the breakdown electric field enhanced significantly and further led to improved energy storage density which was about 43% higher than that of the polylactic acid matrix. The possible reason is that in these composites, the orientation of C–H bonds of MOFs seems more beneficial to the formation of hydrogen bonds between the carboxyl group of formic acid and the polylactic acid matrix. These relationships obtained from formic acid MOFs/polylactic acid composites are valuable to the design of high-performance polymer/MOF energy storage composites and may be a new perspective to the practical use of ferroelectric MOFs.

Synchronous wrapping and inward-etching strategy on constructing yolk-shell MIL-88A@NiFe-PB heterostructures for electrochemical non-enzymatic glucose detection

Construction of heterocompositional hybrid metal–organic frameworks (MOFs) by integration of more than two MOFs is a smart strategy for fine-tuning MOF properties. In this work, a novel yolk-shell MIL-88A@NiFe-PB heterostructure, in which MIL stands for Materials from Institute Lavoisier, and PB represents the coordination network of Prussian Blue, was fabricated through a fast wrapping and then inward-etching growth synthetic strategy under mild stirring condition. The thickness of the outmost layer of NiFe-PB and the internal core structure of MIL-88A can be controlled by tuning the concentration of K4[Fe(CN)6]·3H2O in the assembly system. A rational growth mechanism for the yolk-shell MIL-88A@NiFe-PB heterostructure was proposed. The as-prepared yolk-shell MIL-88A@Ni10Fe PB-50 architectures were then explored for non-enzymatic glucose sensing. The results show that the designed glucose sensor exhibits a high sensitivity of 1963.2 μA mM−1 cm−2 over a wide linear range of 0.005–1.0 mM, a low detection limit (0.12 μM), as well as a fast reaction time (<2 s) and long-term stability for non-enzymatic glucose detection. Also, it shows good applicability in real serum samples. This work provides a “wrapping-inward-etching” synthetic strategy for construction of hybrid MOFs with exceptional outstanding non-enzymatic glucose sensing performance, providing a reasonable guide for construction of other MOF on MOF intriguing structures for electrochemical sensing applications.