Zeolitic Imidazolate Framework Research Articles

Machine Learning Based Insights for Metal-Organic Frameworks Synthesis: A Comparative and Explainable Analysis of ZIF-8 Morphology

Metal-organic frameworks (MOFs) such as zeolitic imidazolate framework-8 (ZIF-8) are promising nanomaterials for various applications like drug delivery and energy storage. The efficacy of ZIF-8 in these applications highly depends on its morphology, including size and shape. However, understanding and controlling morphology during synthesis is challenging due to the complex interactions among synthesis conditions such as precursor concentration and reaction temperature. Traditional trial-and-error methods for morphology optimization are inefficient and cannot effectively account for the combined effects of conditions. Machine learning (ML) offers a powerful alternative for morphology prediction, which can accelerate the reverse engineering process to better understand how synthesis conditions affect morphology. Despite recent advances, developing accurate ML models and selecting the appropriate ones for specific applications remain a challenge. This study addresses these issues by experimentally investigating how variations in synthesis conditions, such as precursor concentrations, solvent properties, and temperature, affect ZIF-8 morphology. Using experimental data, this work further built and compared three ML models: Random Forest (RF), Support Vector Regressor (SVR), and Neural Network (NN). Among these, the NN model has the best performance in terms of R-squared and mean squared errors. These ML models provide insights into how synthesis conditions affect ZIF-8, thus setting the basis for future studies aimed at optimizing conditions and guiding more efficient manufacturing strategy to expand the applications of this versatile nanomaterial.

Acetylene semi-hydrogenation catalyzed by Pd single atoms sandwiched in zeolitic imidazolate frameworks via hydrogen activation and spillover.

The semi-hydrogenation of alkynes into alkenes rather than alkanes is of great importance in the chemical industry, and palladium-based metallic catalysts are currently employed. Unfortunately, a fairly high cost and uncontrollable over-hydrogenation impeded the application of Pd-based catalysts on a large scale. Herein, a sandwich structure single atom Pd catalyst, Z@Pd@Z, was prepared via impregnation exchange and epitaxial growth methods (Z stands for ZIF-8), in which Pd single atoms were stabilized by pyrrolic N in a zeolitic imidazolate framework (ZIF-8). Semi-hydrogenation of acetylene was performed and Z@Pd@Z achieved 100% acetylene conversion at 120 °C with an ethylene selectivity of more than 98.3% at an extra low Pd concentration. Z@Pd@Z exhibited a specific activity of 1872.69 mLC2H4 mgPd-1 h-1, surpassing most of the reported Pd-based catalysts. The existence of Pd single atoms coordinated by nitrogen (Pd-N4) was verified by XAS (synchrotron X-ray absorption spectroscopy), which provided active sites for H2 dissociation and the dissociated hydrogen quickly spilled over the surface of the outer ZIF layer to hydrogenate alkyne to ethene; besides, the catalytic activity could be controlled by adjusting the thickness of the outer ZIF layer. The confinement of the ZIF on Pd single-atom sites and the high energy barrier of ethylene hydrogenation were found to be responsible for the superior C2H2 semi-hydrogenation activity. This work opens up valuable insights into the design of ZIF-derived single-atom catalysts for efficient acetylene selective hydrogenation.

SYNTHESIS OF Zn-Fe BIMETALLIC ZIFs AND STUDY OF THE PHOTOCATALYTIC NITROGEN FIXATION PERFORMANCE

In recent years, in-depth studies of zeolitic imidazolate framework-8 (ZIF-8) materials have revealed that they have many unique properties and uses. Zn-Fe bimetallic ZIFs with bimetallic active centers can be designed and fabricated based on ZIF-8 with good water resistance. The structure, composition, and photoelectrochemical properties of the Zn-Fe bimetallic ZIFs were systematically analyzed by field emission scanning electron microscopy (FESEM), mapping, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and photoluminescence (PL). The bimetallic Zn-Fe ZIFs exhibited strong light absorption properties in the visible region at 390 nm, and the forbidden bandwidths were greatly reduced compared to those of ZIF-8. The photoelectrochemical properties of bimetallic Zn-Fe ZIFs and the separation and migration efficiency of photogenerated charge carriers can be optimized by adjusting the amount of metal introduced. The highest average photocatalytic rate of 1363.53 μmol L-1 g-1 h-1 was observed for bimetallic Zn-Fe ZIFs when Zn:Fe = 1:0.3. Finally, the photocatalytic nitrogen fixation performance of Zn-Fe bimetallic ZIFs is discussed.

In situ growing of ZIF-8 crystals into TiO2 micro columnar films

This study proposes a fast and simple method for the in situ growth of metal-organic frameworks (MOFs) on metal oxide substrates as an alternative to the traditional approaches of using gold substrates and self-assembled monolayers (SAMs). As a case study, zeolitic imidazolate framework 8 (ZIF-8) crystals were grown in micro columnar TiO2 films through simple alternate and successive immersions of the TiO2 films into solutions containing the MOFs precursors. The growth process of the MOF crystals in the interstitial spaces between the TiO2 columns was investigated by varying the metal-to-ligand ratio (1:2, 1:4, and 1:8) and by employing modulating agents such as triethylamine. It was found that the optimal deposition of ZIF-8 occurred when using a higher excess of ligand and the addition of triethylamine after a controlled number of immersion cycles. These results were obtained by using glancing angle X-ray diffraction (GAXRD) and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) as characterization techniques. Additionally, a density functional theory (DFT) study as well as Fourier-transform infrared spectroscopy (FTIR) and GAXRD experiments were conducted to elucidate the nucleation process. It was concluded that the starting point is the formation of a covalent bond between the Zn cations and the TiO2 on the metal oxide surface after immersion of the film into a Zinc (II) nitrate solution, allowing for the formation of MOF nuclei once the film is subsequently immersed in the 2-methylimidazole solution. The results demonstrate the feasibility of in situ growth of MOF crystals onto metal oxide structures by a layer-by-layer strategy, offering a promising alternative to conventional methods.

Enhancing nano zero-valent iron (nZVI) performance for Cr(VI) removal through zeolite imidazole framework-8 (ZIF-8) coating

Enhancing nano zero-valent iron (nZVI) performance for Cr(VI) removal through zeolite imidazole framework-8 (ZIF-8) coating

Efficient adsorption of ofloxacin in a novel nanocomposite formed by nano-hexagonal boron nitride fused with zeolite imidazolite skeleton-8: Experimental and molecular dynamics simulation studies.

With the widespread application of antibiotics in the medical field, associated wastewater pollution has become a critical environmental issue, creating potential risks to ecosystems and public health. This study synthesized three novel nanocomposite materials, ZIF-8@h-BN-X, using an in-situ growth method by adjusting h-BN content. Compared to pure two-dimensional hexagonal boron nitride (h-BN), their adsorption capacities for ofloxacin (OFL) in solution were evaluated. Results showed that zeolitic imidazolate framework-8 (ZIF-8) attached and grew on the h-BN surface, altering surface functional groups and significantly enhancing the nanocomposite's adsorption effect on OFL. Adsorption capacity depended on the initial h-BN content, with lower X content resulting in more active sites and stronger adsorption capacity. Equilibrium adsorption capacities were 145.46, 124.91, and 58.16 mg·g-1 for X values of 29.82 %, 45.93 %, and 62.95 %, respectively. Molecular dynamics simulations revealed interaction energies of -109.13 kcal·mol-1 between ZIF-8@h-BN-X and OFL, compared to -84.78 kcal·mol-1 between pure h-BN and OFL, demonstrating the superior adsorption performance of ZIF-8@h-BN-X. OFL adsorption on ZIF-8@h-BN-X followed the Langmuir isotherm model and pseudo-second-order adsorption kinetics. Thermodynamic parameters indicated that the adsorption process of ZIF-8@h-BN-X was exothermic and spontaneous when compared to h-BN alone. This study highlights the significant potential of ZIF-8@h-BN-X in treating antibiotic-contaminated wastewater, while providing theoretical and practical insights for developing novel, efficient two-dimensional nanocomposite adsorbents.

High-performance hybrid supercapacitors enabled by CoTe@CoFeTe double-shelled nanocubes.

Metal tellurides, known for their superior electrical conductivity and excellent electrochemical properties, are promising candidates for supercapacitor applications. This study introduces a novel method involving a metal-organic framework hybrid to synthesize CoTe@CoFeTe double-shelled nanocubes. Initially, zeolitic imidazolate framework-67 (ZIF67) and CoFe Prussian blue analog (PBA) nanocubes are synthesized through an anion-exchange reaction with [Fe(CN)6]3- ions. Subsequent annealing treatment converts these structures into Co3O4@CoFe2O4 double-shelled nanocubes. These are then subjected to a tellurization process to form CoTe@CoFeTe, which exhibits outstanding supercapacitive performance. Notably, the CoTe@CoFeTe based-electrode demonstrates superior supercapacitive properties compared to their oxide counterparts, mainly due to the introduction of tellurium ions. These nanocubes show an impressive specific capacity of 1312 C g-1 at a current density of 1 A g-1 and maintain 92.35% of their capacity after 10 000 charging cycles, highlighting their durability and the synergistic effect of the mixed metals and their hollow structure. Furthermore, when used as the positive electrode material in a hybrid supercapacitor with activated carbon (AC), the device achieves an energy density of 64.66 W h kg-1 and retains 88.25% of its capacity after 10 000 cycles. These results confirm the potential of the developed material for advanced supercapacitor applications.

Retraction notice to “Engineering of dopamine conjugated with bovine serum albumin and zeolite imidazole framework: A promising drug delivery nanocarrier on lung cancer cells” [Heliyon 10 (2024) e36580]

Retraction notice to “Engineering of dopamine conjugated with bovine serum albumin and zeolite imidazole framework: A promising drug delivery nanocarrier on lung cancer cells” [Heliyon 10 (2024) e36580]

Recent Advances in Zeolitic Imidazolate Frameworks as Drug Delivery Systems for Cancer Therapy

Recent Advances in Zeolitic Imidazolate Frameworks as Drug Delivery Systems for Cancer Therapy

Selective adsorption and separation of C6 hydrocarbons: the role of structural flexibility and functionalization in zeolitic imidazolate frameworks

This work demonstrates selective C6 hydrocarbon separation using functionalized ZIFs, revealing tunable adsorption via structural flexibility and host–guest interactions.

Flexible freestanding carbon nanofiber mats decorated with Zn/Co oxide nanostructures derived from zeolitic imidazolate frameworks as supercapacitor electrodes

Flexible freestanding carbon nanofiber mats decorated with Zn/Co oxide nanostructures derived from zeolitic imidazolate frameworks as supercapacitor electrodes

Nb2CTx-supported bimetallic NPs@ZIF-8 nanohybrid as ECL signal amplifier and peroxidase mimics for chromogranin a immunosensing in human serum and saliva.

Niobium carbide (Nb2CTx), a key component of the MXene family renowned for its utilization in lithium-ion batteries and supercapacitors, remains largely underutilized in biosensing applications. This study introduces a notably sensitive and label-free dual-mode electrochemiluminescence (ECL) and colorimetric immunosensor to specifically detect chromogranin A (CgA) in biological fluids. Initially, AuAg bimetallic nanoparticles (BiMNPs) were synthesized using Nb2CTx as a reducing and supporting material. Furthermore, a promising approach has been put forward to increase the efficacy of the ECL of [Ru (bpy)3]2+ system by integrating the combined use of the zeolitic imidazolate framework-8 (ZIF-8) and the Nb2CTx coated bimetallic NPs. Incorporation produces a significant ~165-fold increase in electrochemical signals and a 4-fold improvement in ECL signals. In particular, BiMNPs@ZIF-8 nanohybrid exhibited significantly enhanced peroxidase-like activity compared to bare BiMNPs, demonstrating synergistic peroxidase enzyme mimicry. This improved activity makes it a potent catalyst for the H₂O₂-mediated oxidation of 3,3,5,5, tetramethylbenzidine (TMB), generating the characteristic blue color. Furthermore, the ECL method achieved a detection range of 0.001 to 1000 pg/mL with LOD of 0.11 fg/mL, while the colorimetric method achieved a LOD of 100 pg/mL and a linear range of 0.1 to 4000 ng/mL. The practical applicability of the sensor was validated by analyzing CgA levels in human serum and saliva samples.

Single-atom Ni-N4 decorated zeolitic imidazolate framework-67 (ZIF-67) for enhanced catalytic activation of peroxymonosulfate: A case study on levofloxacin degradation in water matrices

Single-atom Ni-N4 decorated zeolitic imidazolate framework-67 (ZIF-67) for enhanced catalytic activation of peroxymonosulfate: A case study on levofloxacin degradation in water matrices

ZIF-67-derived NiCo2O4 hollow nanocages coupled with g-C3N4 nanosheets as Z-scheme photocatalysts for enhancing CO2 reduction.

Photocatalytic CO2 reduction technology plays a significant role in the energy and environmental sectors, highlighting the necessity for developing high-efficiency and stable catalysts. In this study, a novel photocatalyst, xNiCo2O4/CN (x=1, 3, and 5wt%), was synthesized by depositing zeolitic imidazolate framework-67 (ZIF-67)-derived nickel cobaltate (NiCo2O4) hollow nanocages onto porous graphitic carbon nitride (g-C3N4, CN) nanosheets for photocatalytic CO2 reduction. Under visible light irradiation, the resulting 3NiCo2O4/CN photocatalyst demonstrated exceptional CO yields of up to 2879.5μmolg-1h-1, surpassing those of NiCo2O4 and CN alone by factors of 3.3 and 11.6, respectively. The introduction of hollow NiCo2O4 nanocages increased the specific surface area of the material and enhanced the number of active sites, while strengthening visible light absorption. The creation of a built-in electric field, induced by the Fermi level difference between the two materials, was confirmed through ultraviolet photoelectron spectroscopy (UPS) characterization. This resulted in the formation of a Z-scheme heterojunction, significantly enhancing the separation and migration of photogenerated charge carriers. Notably, 3NiCo2O4/CN exhibits excellent stability during long-term photocatalytic reactions, ensuring reliable performance for practical applications. This study offers novel insights and methodologies for developing efficient photocatalytic CO2 reduction catalysts.

Facile colorimetric detection of as(V) in Rice with immobilized acid phosphatase on hollow metal-organic frameworks hybrid with peroxidase-like activity

Quantitative analysis of As(V) in rice is of great significance for food safety and heavy metal pollution control. Here, a facile colorimetric method for As(V) detection was constructed by using immobilized acid phosphatase (ACP) in hollow metal-organic frameworks hybrid. Metalloporphyrin and gold nanoparticles modified hollow zeolite imidazole framework-8 [Au/HZIF-8@TCPP(Fe)], named AuHT, was chosen here as ACP immobilizing carrier with peroxidase-like activity. Firstly, the morphology, structure, immobilization efficiency and catalytic ability of obtained AuHT@ACP were fully characterized. Then, based on the inhibition of As(V) on immobilized ACP and cascade reaction mediated by ACP and AuHT, a colorimetric biosensor was established with excellent simplicity. After comprehensive validation, this colorimetric method presented the advantages of wide linear range (10.0–1000.0 μg/L), low LOD (4.0 μg/L), nice accuracy (recovery of 93.7–109.6 %) and good selectivity. Finally, this method was applied to visual detection of As(V) in rice samples with different varieties.

Au nanoparticles anchored carbonized ZIF-8 for enabling real-time and noninvasive glucose monitoring in sweat.

Wearable sensors can easily enable real-time and noninvasive glucose (Glu) monitoring, providing vital information for effectively preventing various complications caused by high glucose level. Here, a wearable sensor based on nanozyme-catalyzed cascade reactions is designed for Glu monitoring in sweat. Au nanoparticles (AuNPs) are anchored to the carbonated zeolitic imidazolate framework-8 (ZIF-8-C), endowing the sensor with Glu oxidase (GOx)-like and peroxidase (POD)-like activity. A flexible screen-printed carbon electrode (SPCE) is decorated with the resultant AuNPs@ZIF-8-C, which is further modified with biocompatible and swellable calcium alginate (CA) gels for the preparation of the wearable Glu sensor. The linear range for Glu detection is 10∼300μM with a limit of detection (LOD) of 4.99μM, which covers the physiological Glu concentration range in human sweat (10-200μM). The developed wearable Glu sensor can fit well with the skin tissues due to the flexibility of the SPCE, and thus it can be successfully applied in real-time and noninvasive monitoring of Glu in human sweat. Additionally, the wearable Glu sensor exhibits high antibacterial activity resulted from the generated hydroxyl radicals (·OH), enabling long-term Glu monitoring in sweat.

Tannic acid modified zeolitic imidazolate framework-8 membrane with macrosized cavities for efficient oil-in-water emulsion separation

Tannic acid modified zeolitic imidazolate framework-8 membrane with macrosized cavities for efficient oil-in-water emulsion separation

Light-induced charge transfer from a fullerene to a zeolitic imidazolate framework enhances alkaline electrocatalytic hydrogen production.

In the process of water electrolysis, the oxygen evolution reaction (OER) suffers from a high energy barrier, which has become a key factor restricting the large-scale commercial application of renewable energy technology. Therefore, it is necessary to develop a durable, efficient, low-cost and environmentally friendly OER electrocatalyst. In the present work, a photo-responsive fullerene (C60) was encapsulated in the cavity of cobalt-containing flake-like zeolitic imidazolate framework-67 (C60@F-ZIF-67). Benefiting from the light-induced charge/energy transfer from the fullerene carbon cage to the metal Co active sites, the as-synthesized C60@F-ZIF-67 exhibited remarkably enhanced OER activity under UV light irradiation. Specifically, the overpotential of 10 mA cm-2 for C60@F-ZIF-67 decreased from 465 mV in the dark to 324 mV under light in 1 M KOH, amounting to an activity improvement of approximately 30.32%. This work provides a new route for the design and construction of photo-assisted efficient electrocatalysts for water splitting.

Insights into the post-combustion CO2 capture performance of zinc-based zeolitic imidazolate framework (ZIF8)-derived nanocomposites

We report carbon-zinc oxide (C/ZnO) nanocomposites obtained by a simple, scalable, and cost-effective one-step pyrolysis of a zinc-based zeolitic imidazolate framework (ZIF8) for post-combustion carbon dioxide (CO2) capture. The prepared nanocomposites are thoroughly analyzed by different characterization techniques. The CO2 adsorption–desorption studies performed using thermogravimetric analyzer (TGA) reveal remarkable CO2 adsorption capacity (∼10 wt% at 30 °C, 1 bar) and excellent CO2/N2 selectivity. The low-pressure CO2 uptake capacities measured using Brunauer-Emmett-Teller (BET) analyzer corroborate the TGA results. The best sample exhibits an uptake of 3.13 mmol/g at 30 °C, 1 bar. The experimental isotherms obtained using TGA and BET are fitted using suitable kinetic and adsorption models, respectively, to obtain insights into the underlying adsorption mechanisms. The isosteric enthalpy of adsorption calculated from the Virial analysis of the isotherms confirms the physisorption nature. Excellent CO2 uptake values are also observed in simulated flue gas environments. Additionally, the factors influencing the CO2 adsorption in these nanocomposites are identified by correlating the physical characterization results with the CO2 uptake studies. It is inferred that the amorphous carbon in the nanocomposite determines the adsorption capacity and selectivity, whereas the residual ZnO in it controls the adsorption capacity at 0.15 bar and kinetics.

Characterization of zeolitic imidazole framework (ZIF-8) catalyst for potential biodiesel production from waste cooking oil (WCO)

Heteropoly acids (HPAs) catalysts prove effective in waste cooking oil biodiesel production, considering their high density of Brønsted acidic sites, exhibit significant resilience to elevated levels of free fatty acid (FFA) and moisture content. However, the separation of HPA catalysts after biodiesel production is challenging due to their homogeneous catalytic nature. This study aims to develop magnetic vanadium-substituted HPAbased ZIF-8 composites to create a catalyst for biodiesel production from WCO that is more efficient and easier to separate. In this work, a range of analytical methods was utilized to characterize the catalyst, such as Fouriertransform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), highresolution transmission electron microscopy (HRTEM), and a vibrating sample magnetometer (VSM). The successful incorporation of HPA acid into the magnetite ZIF-8 nanocomposite was indicated by prominent bands in the FTIR analysis, and this formation was further validated by EDX analysis. The VSM results also revealed that the nanocomposite has good magnetic responsiveness, facilitating catalyst separation and recycling. The magnetic ZIF-8 composites functionalized with H6PV3MoW8O40 demonstrated significant potential for sustainable biodiesel production from WCO.