Zeolitic Imidazolate Framework Research Articles

Nano-enzyme hydrogels for cartilage repair effectiveness based on ternary strategy therapy.

Designing artificial nano-enzymes for scavenging reactive oxygen species (ROS) in chondrocytes (CHOs) is considered the most feasible pathway for the treatment of osteoarthritis (OA). However, the accumulation of ROS due to the amount of nano-enzymatic catalytic site exposure and insufficient oxygen supply seriously threatens the clinical application of this therapy. Although metal-organic framework (MOF) immobilization of artificial nano-enzymes to enhance active site exposure has been extensively studied, artificial nano-enzymes/MOFs for ROS scavenging in OA treatment are still lacking. In this study, a biocompatible lubricating hydrogel-loaded iron-doped zeolitic imidazolate framework-8 (Fe/ZIF-8/Gel) centrase was engineered to scavenge endogenous overexpressed ROS synergistically generating dissolved oxygen and enhancing sustained lubrication for CHOs as a ternary artificial nano-enzyme. This property enabled the nano-enzymatic hydrogels to mitigate OA hypoxia and inhibit oxidative stress damage successfully. Ternary strategy-based therapies show excellent cartilage repair in vivo. The experimental results suggest that nano-enzyme-enhanced lubricating hydrogels are a potentially effective OA treatment and a novel strategy.

Sn Nanoclusters Confined in COP‐Derived Carbon for Catalytic Oxygen Reduction Reaction

AbstractThe development of catalysts composed of single atoms is crucial for enhancing the performance of oxygen reduction reaction (ORR). However, the unsatisfactory intrinsic activity of these catalysts still poses a major challenge, limiting their overall effectiveness. One approach to addressing this challenge is the introduction of metal clusters, which can form a synergistic effect with the single atoms, ultimately improving their performance. In this study, core‐shell structured carbon polymer is constructed with Zn atoms and Sn nanoclusters by directly subjecting pyrolysis of the covalent organic polymer (COP) and metal organic framework (MOF) (COP@MOF). The thin COP shell serves a dual purpose: it prevents the collapse and aggregation of zeolitic imidazolate framework‐8 (ZIF‐8) and promotes the formation of mesopores, facilitating mass transport and enhancing the graphitization degree to improve conductivity. The resulting Sn‐COP@MOF800 exhibits promising catalytic performance in the ORR, demonstrating a half‐wave potential of 0.81 V and current density of 5.56 mA cm−2 in 0.1 m KOH, which is comparable to that of Pt/C. This study provides new ideas for exploring the application of metal single atoms and metal nanoclusters in ORR catalysis through synergistic effects.

Heteroatom Sulfur-Modified ZIF-8 Derived Zn, N Co-Doped Carbon Nanocages as Highly Efficient ORR Catalysts for Zn-Air Batteries

Carbon-based electrocatalysts derived from zeolitic imidazolate framework-8 (ZIF-8) have garnered significant attention, owing to their structural advantages, high surface area, and tunable active sites. Herein, we report the synthesis of heteroatom sulfur (S) modified ZIF-8 derived carbon nanocages (ZnS@N/S-C) for oxygen electrocatalysis through self-assembly and two-step pyrolysis. The resultant ZnS@N/S-C exhibits catalytic activity towards oxygen reduction reaction (ORR) with high half-wave potential (0.86 V) and stability (91.4%), separately, which is comparable to or superior to Pt/C. Furthermore, the application of ZnS@N/S-C as a cathode for Zn-air batteries (ZABs) demonstrates performance metrics such as an open-circuit voltage of 1.407 V, a power density of 114.4 mW cm−2, and a specific capacity of 764.6 mAh gZn −1, etc surpassing Pt/C. The performance of ZnS@N/S-C can be attributed to the fact that the introduction of S significantly increases the specific surface area, pore volume, and defect extent of the catalyst, while optimizing the electronic structure and generating ZnS active nanocrystals. This work employs a simple sulfurization strategy to enhance the ORR activity of ZIF-8-derived Zn-based catalysts with fully filled 3d orbitals, providing guidance for the development of such materials.

Structural Origin of the Deformation Propensity of Zeolitic Imidazolate Framework Glasses

Structural Origin of the Deformation Propensity of Zeolitic Imidazolate Framework Glasses

Fluorescence sensing probe based on functionalized mesoporous MOFs for non-invasive and detection of dopamine in human fluids

Abnormal amount of dopamine (DA) in human body is closely relate to various diseases, such as Parkinson's disease, pheochromocytoma. Real-time monitoring DA is crucial for disease warning, diagnosis and treatment. Currently, most methods rely on invasive blood testing for detecting DA, which is only completed with the aid of the medical staffs in hospitals. Herein, a non-invasive fluorescence visual strategy is developed for the real-time monitoring DA, based on luminescent nanoparticles and modified mesoporous zeolite imidazole framework (ZIF-8-NH2) dodecahedrons. During the reaction process, DA is enriched through the spatial configuration of ZIF-8-NH2 and hydrogen bonding effect. The luminescence of Cr3+-doped zinc gallate (ZnGa2O4:Cr3+, ZGC) is inhibited by the photo-induced electron transfer (PET) mechanism to realize sensitively detecting DA. The intelligent sensing platform based on the designed fluorescence probe and color recognition system is structured for real-time detection of DA in urine. Furthermore, a skin-fitting hydrogel patch is prepared by combining a fluorescent probe with chitosan, which enables sensitive and accurate detection of DA in sweat without the complex sample pretreatment. The non-invasive fluorescence detection method provides an effective strategy for quantitatively monitoring DA in human fluids.

Photocatalytic performance and mechanism insights of an S-scheme ZnMn2O4/ZIF-67 heterostructure in photocatalytic CO2 reduction under visible light irradiation

Improved separation among photoelectrons and holes (e−, h+) and regulated electron transport routes are essential to improve photocatalytic performance. This work adopts a convenient but more efficient method to prepare an S-scheme composite photocatalyst integrating narrow band gap semiconductor ZnMn2O4 (ZMO) and zeolitic imidazole framework ZIF-67(Z67) for improved photocatalytic CO2 reduction. The designed photocatalyst ZMO(X)/Z67 showed more visible light harvesting capacity compared to individual ZMO and Z67. The ZMO/Z67 nanocomposite containing 3 % ZMO nanosphere produced 1.91 times higher methanol (48.64 μmolg−1) compared to pure Z67 (25.36 μmolg−1) and 1.42 times higher ethanol (30.32 μmolg−1) compared to pure Z67 (21.28 μmolg−1) after 8 h visible light illumination. The composites' increased photocatalytic performance might be attributed primarily to excellent photogenerated charge separation and transfer via the linked S-scheme heterojunction between ZMO nanospheres and Z67. Various characterization methods are used to explore the structural, morphological, optical, and electrochemical features of produced photocatalysts, and a thorough photocatalytic mechanism is provided. After four recycling, the composite photocatalyst demonstrated good stability and recyclability. This study attributed to a viable method for constructing a direct S-scheme heterojunction for photocatalytic CO2 reduction.

Decorated and sculpted zeolitic imidazolate frameworks for electrocatalytic carbon dioxide reduction to formate

The production of value-added chemicals using electrocatalytic CO2 reduction (ECR) is an effective strategy to achieve “carbon neutrality”. However, highly formate-selective production with zinc-based catalysts in ECR systems remains a challenge. In this work, a macroporous hollow nanocage structure was successfully created through the etching of zeolitic imidazolate frameworks (ZIFs) using phytic acid (PA). The surface of the hollow nanocage was then adorned, leading to the formation of a hybrid superstructure product (ZIF-P5/In) with a substantial surface area, enabling effective ECR to formate. The Faraday efficiency of ZIF-P5/In for formate is 80.2 % at −1.26 VRHE. This feasible strategy is expected to provide new insights into the preparation of highly efficient ZIF-derived electrocatalysts.

Designing a MOF-functionalized Nanofibrous Aerogel via Vapor-Phase Synthesis.

Designing 3D mechanically robust and high-surface-area substrates for uniform and high-density deposition of metal-organic frameworks (MOFs) provide a promising strategy to enhance surface accessibility and application of these highly functional materials. Nanofibrous aerogel (NFA) with its highly porous self-supported structure composed of interconnected nanofibrous network offers an ideal platform in this regard. Herein, a facile one-pot strategy is introduced, which utilizes direct deposition of MOF on the nanofibrous surface of the NFAs. NFAs are synthesized using electrospun polyacrylonitrile/polyvinylpyrrolidone (PAN/PVP) polymer nanofibers containing zinc acetate (Zn(Ac)2), which are subjected to freeze drying and thermal treatment. The latter converts Zn(Ac)2 to zinc oxide (ZnO), providing the sites for MOF growth while also adding mechanical integrity to the NFAs through cyclization of the PAN. Exposure of the NFA to the vapor-phase of organic ligand, 2-methylimidazole (2-MeIm) enables in situ growth of zeolitic imidazolate framework-8 (ZIF-8) MOF on the NFA. ZIF-8 loading on the NFAs is further improved by more than tenfold by synthesizing ZnO nanorods/protrusions on the nanofibers, which enables more sites for MOF growth. These findings underscore a significant advancement in designing MOF-based hybrid aerogels, offering a streamlined approach for their use in diverse applications, from catalysis to sensing and water purification.

Application of Langmuir and Freundlich isotherm, pseudo-first-order, and pseudo-second-order kinetic studies for the adsorption of sunset yellow dye onto Cadmium-based imidazole zeolite nanostructure

ABSTRACT Zeolitic-imidazole framework (Cd-ZIF) was synthesised and characterised. Cd-ZIF was accomplished by Fourier transfer infrared (FTIR), field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD), energy-dispersive spectrum (EDX), and Brunauer–Emmett–Teller (BET). The synthesised zeolite was used in the (SY) adsorption. The impact of different variables on batch method as a function of solution pH, concentration of SY, dose of Cd-ZIF, contact time and temperature were analysed and optimal conditions were determined. The point of the zeolite zero charge (pHPZC) was obtained at 7.0. The optimal conditions were obtained at pH = 5, the initial concentration C 0 = 160 mg L−1, 30 mg of Cd-ZIF, t = 60 min, and 40°C. Langmuir and Freundlich models were employed by equilibrium data from SY adsorption process. The results showed that Freundlich model was fitted. Therefore, the adsorbent had a surface heterogeneity. The adsorption capacity increased with increasing the temperature up to 40°C, which showed the endothermic adsorption. Further temperature (at 45°C), the adsorption decreased because of electrostatic attraction between free and adsorbed SY molecules. The kinetics of adsorption indicated that SY adsorption followed a pseudo-second-order model and chemisorption.

Enhancing cellulose hydrolysis via cellulase immobilization on zeolitic imidazolate frameworks using physical adsorption.

This study investigates the immobilization of cellulase on zeolitic imidazolate frameworks (ZIFs) by physical adsorption, specifically the ZIF-8-NH2 and Fe3O4@ZIF-8-NH2, to enhance enzymatic hydrolysis efficiency. The immobilization process was thoroughly analyzed, including optimization of conditions and characterization of ZIF carriers and immobilized enzymes. The impacts on the catalytic activity of cellulase under various temperatures, pH levels, and storage conditions were examined. Additionally, the reusability of the immobilized enzyme was assessed. Results showed the cellulase immobilized on Fe3O4@ZIF-8-NH2 exhibited a high loading capacity of 339.64 mg/g, surpassing previous studies. Its relative enzymatic activity was found to be 71.39%. Additionally, this immobilized enzyme system demonstrates robust reusability, retaining 68.42% of its initial activity even after 10 cycles. These findings underscore the potential of Fe3O4@ZIF-8-NH2 as a highly efficient platform for cellulase immobilization, with promising implications for lignocellulosic biorefinery.

PH/redox-responsive release of interleukin-4 from ZIF-8@diselenide block copolymer to regulate inflammation

Multi-responsive drug-delivery systems have been widely explored to enable specific delivery to target sites. Here, interleukin-4 (IL-4), an anti-inflammatory cytokine, is first encapsulated in situ inside a zeolitic imidazolate framework (ZIF-8) to form IL-4@ZIF-8, which is subsequently coated with a diselenide block copolymer to obtain IL-4@ZIF-8@Se-Se-polymer. This delivery system enables redox-responsive release of IL-4 by the diselenide copolymer and a pH-triggered release by ZIF-8. Moreover, IL-4 release is precisely controlled stepwise by the stimuli response, with the dissociation of the diselenide copolymer, and breakdown of the ZIF-8 structure. The targeted release property of the IL-4@ZIF-8@Se-Se-polymer endows the materials with efficient macrophage immune regulation, as systematically demonstrated in vitro. This study provides an effective example of the delivery and on-demand release of IL-4, and may find promising applications in tissue engineering for the management of inflammation.

Synthesis and High-Pressure and Guest-Mediated Gate-Opening, Breathing, and Phase Transitions of Heterolinker Zeolitic Imidazolate Framework ZIF-60 Derivatives

Synthesis and High-Pressure and Guest-Mediated Gate-Opening, Breathing, and Phase Transitions of Heterolinker Zeolitic Imidazolate Framework ZIF-60 Derivatives

Correction to “Ni-Loaded 2D Zeolitic Imidazolate Framework as a Heterogeneous Catalyst with Highly Activity for Ethylene Dimerization”

Correction to “Ni-Loaded 2D Zeolitic Imidazolate Framework as a Heterogeneous Catalyst with Highly Activity for Ethylene Dimerization”

A networked iron and nitrogen-doped ZIF-8/MWCNTs heterostructure for oxygen reduction reaction.

Zeolitic Imidazolate Frameworks-8 (ZIF-8) is commonly used as an ideal precursor for non-noble metal catalysts because of its high specific surface area, ultra-high porosity, and N-rich content. Upon pyrolyzing ZIF-8 at 900 °C in Ar, the resulting material, referred to as Z8, displayed good activity toward the oxygen reduction reaction (ORR). Then the ZIF-8 was mixed with various conductive carbon materials, such as multiwall carbon nanotubes (MWCNTs), Acetylene black (ACET), Vulcan XC-72R (XC-72R), and Ketjenblack EC-600JD (EC-600JD), to form Z8 composites. The Z8/MWCNTs composite exhibited enhanced ORR activity owing to its network structure, meso-/microporous hierarchical porous structure, improved electrical conductivity, and graphitization. Subsequently, iron and nitrogen co-doping is achieved through the pyrolysis of a mixture comprising Fe, N precursor, and ZIF-8/MWCNTs, which is denoted as FeN-Z8/MWCNTs. The intrinsically high electrical conductivity of MWCNTs facilitated efficient electron transfer during the ORR, while the meso-/microporous hierarchical porous structure and network structure of Fe, N co-doped ZIF-8/MWCNTs promoted oxygen transport. The presence of Fe-containing species in the catalyst acted as activity centers for ORR. This strategy of preparing Z8 composites and modifying them with Fe, N co-doping offers an insightful approach to designing cost-effective electrocatalysts.

Cellulose nanocrystals mediated spontaneous weaving of ZIF-67 hybrid networks: Enhanced peroxymonosulfate activation and rapid removal of dye

Inter-connected zeolite imidazolate framework-67 (ZIF-67) hybrid networks were successfully synthesized by a cellulose nanocrystals (CNCs) mediated spontaneous weaving strategy, which was denoted as ZIF-67@CNC, and was applied to activate peroxymonosulfate (PMS) for Rhodamine B (RhB) degradation. Characterizations results demonstrated that the ZIF-67 nanocrystals are encapsulated within CNCs and subsequently arranged in a string-like configuration. In comparison to pristine ZIF-67, the ZIF-67@CNC catalyst presented superior performances for RhB dye removal both in terms of degradation efficiency and rate, as the kinetic rate constant increased 5.8-fold. This finding was attributed to the improvement in oxygen-containing groups and meso/microporous structures after the introduction of CNCs, leading to efficient binding to compounds and rapid molecular diffusion. Moreover, the ZIF-67@CNC exhibited remarkable stability throughout the catalysis process in aqueous solutions owing to the robust crosslinking between negatively charged CNCs and positively charged cobalt ions, which significantly mitigated the potential secondary pollution of cobalt to the environment. This research opens up new possibilities for the design of highly efficient and durable ZIF-67-based catalysts to promote future wastewater treatment technology.

Spin Density Studies of Tetrahedral Cu(II) Ions Doped into Porous Zeolitic Imidazolate Frameworks

Spin Density Studies of Tetrahedral Cu(II) Ions Doped into Porous Zeolitic Imidazolate Frameworks

Amino Functionality Enables Aqueous Synthesis of Carboxylic Acid-Based MOFs at Room Temperature by Biomimetic Crystallization.

Enzyme immobilization within metal-organic frameworks (MOFs) is a promising solution to avoid denaturation and thereby utilize the desirable properties of enzymes outside of their native environments. The biomimetic mineralization strategy employs biomacromolecules as nucleation agents to promote the crystallization of MOFs in water at room temperature, thus overcoming pore size limitations presented by traditional postassembly encapsulation. Most biomimetic crystallization studies reported to date have employed zeolitic imidazole frameworks (ZIFs). Herein, we expand the library of MOFs suitable for biomimetic mineralization to include zinc(II) MOFs incorporating functionalized terephthalic acid linkers and study the catalytic performance of the enzyme@MOFs. Amine functionalization of terephthalic acids is shown to accelerate the formation of crystalline MOFs enabling new enzyme@MOFs to be synthesized. The structure and morphology of the enzyme@MOFs were characterized by PXRD, FTIR, and SEM-EDX, and the catalytic potential was evaluated. Increasing the linker length while retaining the amino moiety gave rise to a family of linkers; however, MOFs generated with the 2,2'-aminoterephthalic acid linker displayed the best catalytic performance. Our data also illustrate that the pH of the reaction mixture affects the crystal structure of the MOF and that this structural transformation impacts the catalytic performance of the enzyme@MOF.

Adsorption efficacy of acetone with zeolitic imidazolate frameworks–8: a mechanistic and kinetic insight

ABSTRACT The zeolitic imidazolate framework-8 (ZIF-8) has been investigated for the dynamic adsorption of acetone from the gas phase. In this study, ZIF-8 was synthesised using a cost-effective and environmentally friendly method and characterised using SEM, XRD, BET, and FTIR. The synthesised ZIF-8 possessed a BET surface area of 1212 m2. g−1 and a 0.64 µm particle size. The dynamic adsorption efficacy of acetone on the thermally pretreated ZIF-8 was investigated in a gas matrix under different operational factors. Increasing the acetone concentration through the adsorbate inlet from 300 to 800 ppm enhanced the adsorption capacity from 114 to 162 mg. g−1, while increasing flow rates from 100 to 200 mL. min−1 diminished the adsorption capacity from 120 to 114 mg. g−1. Additionally, increasing the relative humidity from 30 to 70% diminished the adsorption capacity from 130 to 87 mg. g−1. The acetone adsorption kinetics on ZIF-8 were investigated by the Elovich equation, pseudo-first order (PFO), and pseudo-second order (PSO) models. The statistical parameters indicated that the Elovich equation model is most suitable for representing the kinetic behaviour. In conclusion, ZIF-8 could be introduced as a sorbent with suitable potential for adsorbing acetone from the air in various environmental and occupational settings.

Coupling the fast electron transportation of cobalt diselenide-based anode via cationic modulation for high rate Na+ storage

The sodium-ion batteries (SIBs), as compelling candidate for partially replacing lithium-ion batteries (LIBs) in relevant application scenarios, is gaining increasing attention. The development of high-rate performance anode materials for sodium-ion batteries is exceptionally crucial. Here, a ZIF (zeolitic imidazolate framework) compound targeting bimetallic cations has applied through a pyrolysis-induced in-situ selenization strategy. This resulted in a nitrogen-doped porous carbon-encapsulated Fe-ion-modified CoSe2 material with a rhombic dodecahedron morphology (Fe-CoSe2@NC). The architecture not only effectively alleviates the bulk stress induced by the insertion/extraction of sodium ions, but also enhances the migration and transport of electrons/ions. Additionally, Fe doping enhances the material's conductivity and expedites reaction kinetics. Consequently, the Fe-CoSe2@NC exhibits outstanding rate performance and cycling stability (362.54 mAh g-1 after 1000 cycles at a current density of 10.0 A g-1) when utilized as an anode for SIBs in a coin-type half-cell. The Fe-CoSe2@NC also delivers a high initial coulombic efficiency (ICE) of 70.14%. This is substantiated by diffusion analysis and in-situ electrochemical impedance spectroscopy (EIS) characterization. The charging and discharging mechanisms of Fe-CoSe2@NC were verified through XRD and TEM characterizations during the electrochemical processes. When coupled with Na3V2(PO4)3 as the cathode material to form a full cell, the Fe-CoSe2@NC// Na3V2(PO4)3 battery system achieves a high energy density of 112.05 Wh kg-1. In this study, the successful construction of a transition metal selenide anode material for SIBs characterized by a stable structure and facilitation of rapid ion migration was demonstrated.

Mechanism of efficient adsorption for arsenic in aqueous solution by zeolitic imidazolate framework‑8.

Arsenic (As) is one extremely hazardous and carcinogenic metalloid element. Due to mining, metal smelting, and other human activities, the pollution of water (especially groundwater) and soil caused by As is increasingly serious, which badly threatens the environment and human health. In this study, a zeolite imidazolate framework (ZIF-8) was synthesized at room temperature and employed as an adsorbent to facilitate the adsorption of As(III) and As(V) from the solution. The successful synthesis of ZIF-8 was demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) revealed that its particle size was approximately 80nm. The adsorption kinetics, adsorption isotherm, solution pH, dose, coexisting ions, and the synonymous elements antimony (Sb) were conducted to study the adsorption of As by ZIF-8 nanoparticles. The maximum saturation adsorption capacity was determined to be 101.47mg/g and 81.40mg/g for As(III), and As(V) at initial pH = 7.0, respectively. Apparently, ZIF-8 had a good removal effect on As, and it still maintained a good performance after four cycles. The coexisting ions PO43- and CO32- inhibited the adsorption of both As(III) and As(V). ZIF-8 performed well in removing both As and Sb simultaneously, although the presence of Sb hindered the adsorption of both As(III) and As(V). Both FTIR and XPS indicated the adsorption mechanism of As on ZIF-8: ZIF-8 generates a large amount of Zn-OH on the surface through hydrolysis and partial fracture of Zn-N, both of which form surface complexes with As.