Metal-organic Framework Composites Research Articles

Hierarchical Assembly of Ternary MOF-Derived Sandwich Composites for High-Efficiency Tunable Electromagnetic Wave Absorption.

The proliferation of electronic devices drives the adoption of electromagnetic wave (EMW) absorbing materials to mitigate electromagnetic pollution. Metal-organic frameworks (MOFs) reveal great potential in EMW absorption field due to their unique pore structure and outstanding physicochemical properties. However, single MOFs are difficult to achieve both efficient absorption and wide frequency coverage owing to the limited electromagnetic properties and structural composition. Herein, a sandwich-like ternary MOF composite is successfully synthesized through a hierarchical assembly strategy. Following high-temperature treatment, the materials are converted into nitrogen-doped porous carbon with magnetic metals, non-magnetic metal oxides, and carbon nanotubes on the surface (labeled as TiO2/C@Co/N/C@CNT). The unique sandwich structure of the resulting derivatives provides a multi-level microstructure and multi-component synergistic effects, significantly enhancing electromagnetic wave absorption capabilities and broadening the effective absorption bandwidth (EAB). At 1.8 mm matching thicknesses, the material achieves a reflection loss of -56.3 dB and a 6.6 GHz EAB. Adjusting the matching thicknesses to 2.3 and 3.1 mm extends the EAB to 6.1-18 GHz, with absorption peaks of -47.6 and -47.1 dB. This work offers a novel guidance for constructing advanced MOF-derived materials with ultra-broadband EAB and strong EMW absorption through meticulous structural design and multiple components combination.

Functional metal-organic frameworks derived electrode materials for electrochemical energy storage: a review.

Pristine metal-organic frameworks (MOFs) are built through self-assembly of electron rich organic linkers and electron deficient metal nodes via coordinate bond. Due to the unique properties of MOFs like highly tunable frameworks, huge specific surface areas, flexible chemical composition, flexible structures and a large volume of pores, they are being used to design the electrode materials for electrochemical energy storage devices. As per the literature, MOFs (including manganese, nickel, copper, and cobalt-based zeolitic imidazolate frameworks (ZIFs), University of Oslo (UiO) MOFs, Hong Kong University of Science and Technology (HKUST) MOFs and isoreticular MOFs (IRMOFs)) have attracted much attention in the field of supercapacitors (SCs)/batteries. According to their dimensionality such as 1D, 2D and 3D, pristine MOFs are mainly used as SC materials. Highly porous materials and their composites are capable for intercalation of metal ions (Na+/Li+). Moreover, the supramolecular features (π⋯π, C-H⋯π, hydrogen bond interactions) of redox stable MOFs provide better insight for electrochemical stability. So, this review provides an in-depth analysis of pure MOFs and MOF derived composites (MOF composites and MOF derived porous carbon) as electrode materials and also discusses their metal ion charge storage mechanism. Finally, we provide our perspectives on the current issues and future opportunities for supercapacitor materials.

Defect strategies in Mn-doped metal–organic frameworks to enhance adsorption-based NOx gas sensing performance

Post-synthetic metalation (PSM) represents a powerful toolkit for modifying the chemical composition of pre-formed metal-organic frameworks (MOFs). However, accessing defective MOFs with exchanged metal nodes via this approach remains challenging. Herein, we report a transmetalation strategy to induce desired metal exchange frustrated flexibility defects in a prototypical MOF platform. Specifically, the pristine Zn-based MOF undergoes selective Zn-to-Mn exchange through a carefully controlled solvothermal transmetalation process. This protocol generates a series of Mn-doped MOFs with increasing Mn integration and the concomitant formation of defect sites within the framework. Detailed structural characterization confirms the successful Mn doping and illuminates the generation of vacancies and distortions around the exchanged Mn nodes. The transmetallated Mn-doped MOF materials exhibit altered chemical environments, as probed by spectroscopic techniques, and display promising sensing activity for NOx through the MOF matrix membrane. The proposed application of the MOF samples as an adsorbent-based chemical sensor includes sensing mechanisms for NO2 gas.

Building block design of thermally regenerable metal–organic framework composites for highly selective lithium adsorption

Crown ether-based organic lithium adsorbent has good stability for diverse lithium extraction scenarios, but hindering by its relatively low selectivity. Here, we report a building block design strategy for fabricating highly selective and thermally regenerable 12-crown-4 (12CE4) based lithium adsorbent. The synergistic coordination and ion-sieving blocks can sufficiently improve the ion selectivity and adsorption capacity of pNCE@MOF fabricated by copolymerizing thermosensitive segment and 12CE4 inside MOF. With the aid of synergistic coordination component of sulfonate group (SS), its Li+/Mg2+ selectivity increased from 12.9 to 21.8 (pNCE-SS@UiO-66) tested in 10,000 ppm salt solutions. Moreover, the 6.0 Å window of UiO-66 could successfully sieve hydrated Li+ (7.64 Å) and Mg2+ (8.56 Å), enhancing the selectivity 3.3 times from 5.1 for pNCE-SS@MOF-808 (10.0 Å) to 21.8. The adsorption capacity of pNCE-SS@UiO-66 was also optimized from 1.00 to 1.47 mmol·g−1. Furthermore, this material demonstrated a lithium selectivity of 11.5–19.8 in synthetic brines with a Mg/Li ratio of 1 to 0.1. Importantly, it could be fully regenerated in warm water at ≥ 40 °C. This work opens the door to constructing highly ion-selective functional materials via a modular method.

Construction of hydrophobic HKUST-1 in wood with selective adsorption performance for toluene and moisture blends

The effect of moisture on the volatile organic compound (VOC) adsorption on biomass-derived metal–organic framework composites is significant in practical applications. In this study, wood-based metal organic frameworks (MOF199-W) and hydrophobic MOF199-W (HMOF199-W) were developed using HKUST-1 (MOF199) and long alkyl chains to investigate the adsorption performance of toluene and enhance the selectivity of adsorption under high humidity conditions. The results demonstrated that HKUST-1 could be anchored onto the surface of wood vessels and fibers through coordination with Cu2+, resulting in an improved surface area in comparison to natural wood. The toluene adsorption capacity of MOF199-W with a 20 % loading was comparable to that of an equivalent amount of MOF199, with adsorption capacities of 323.5 mg/g and 369.9 mg/g, respectively. Further, the Yoon-Nelson model was found to adequately describe the dynamic adsorption process. Following the introduction of long alkyl chains, MOF199 and MOF199-W were endowed with strong hydrophobic character (water contact angle of 107.0◦, 104.0◦, and water uptake of 30.5 mL/g, 55.3 mL/g). With the increase in humidity, the adsorption performance of MOF199 and MOF199-W for toluene sharply decreased, but HMOF199 and HMOF199-W still maintained the adsorption capacities at 304.7 mg/g and 226.7 mg/g, even under 80 % RH conditions. Therefore, HMOF199-W has shown great potential in wooden building materials with the ability for toluene capture under humid conditions.

Customizing Ionic Liquids Functionalized MOFs Composites with Hydrophobic Interface for Electrochemical CO2 Reduction.

The electrochemical carbon dioxide reduction reaction (CO2RR) to generate feedstocks for chemical products (e.g., carbon monoxide, CO) offers a highly attractive method for achieving the closure of the carbon cycle. Ionic liquids (ILs)-functionalized Cu-based catalyst Cu2O-HKUST-1/IL1/PTFE was developed, configuring metal-organic frameworks(MOFs) based materials with high adsorption and multiple active sites. The modified electrocatalysts exhibited high specific surface area, strong CO2 adsorption capacity, abundant active sites, and fast charge transfer rate. The nucleophilic active site of deprotonation at the C2 site in imidazole ILs further improved the selectivity of proton migration and CO product generation, which was verified through DFT calculations for the low Gibbs free energy of the generated intermediate interactions. In addition, the hydrophobic interface constructed by PTFE facilitated the inhibition of the hydrogen evolution reaction (HER) and significantly improved the efficiency of CO2 electroreduction. The Cu2O-HKUST-1/IL1/PTFE catalyst manifested a high C1 Faraday efficiency (FE) up to 96.5% and in particular 92.7% for FECO at -1.7 V vs RHE. The present work provides an efficient strategy for configuring ILs-functionalized MOFs-based materials with good hydrophobic interfaces to enhance the efficiency of CO2 electroreduction to C1 products.

Emerging insights into the application of metal-organic framework (MOF)-based materials for electrochemical heavy metal ion detection

Heavy metal ions are one of the main sources of water pollution, which has become a major global problem. Given the growing need for heavy metal ion detection, electrochemical sensor stands out for its high sensitivity and efficiency. Metal-organic frameworks (MOFs) have garnered much interest as electrode modifiers for electrochemical detection of heavy metal ions owing to their significant specific surface area, tailored pore size, and catalytic activity. This review summarizes the progress of MOF-based materials, including pristine MOFs and MOF composites, in the electrochemical detection of various heavy metal ions. The synthetic methods of pristine MOFs, the detection mechanisms of heavy metal ions and the modification strategies of MOFs are introduced. Besides, the diverse applications of MOF-based materials in detecting both single and multiple heavy metal ions are presented. Furthermore, we present the current challenges and prospects for MOF-based materials in electrochemical heavy metal ion detection.

Achieving a high‐performance anti‐corrosive polyvinyl ester based on bisphenol a coating by addition of polyaniline‐Cu‐based metal organic framework composite

AbstractCorrosion of steel is one of the challenging issues that researchers has focused on it. Among corrosion control methods, organic coatings with suitable lifetime and efficiency are a great of interest. In the present research, polyaniline‐ copper‐based metal organic framework (PANI‐Cu‐MOF) is synthesized using in‐situ oxidation polymerization method and successfully characterized with different techniques. Then, 0.5, 1, and 1.5 wt. % of PANI‐Cu‐MOF composite are added to vinyl ester (VE) resin based on bisphenol A and coated on ST37 steel. The performance of the as‐prepared coatings on ST37 is evaluated using electrochemical impedance spectroscopy (EIS) for 360 h. The EIS results showed that loading of PANI‐Cu‐MOF (0.5 wt. %) in VE led to the highest protective properties against aggressive species with |Z|0.01 Hz = 6.76 × 107 Ωcm2 after 360 h. The uniform distribution of PANI‐Cu‐MOF composite in VE and its hydrophobic property causes a delay in the penetration of the corrosive species into the coating, thus increasing the corrosion resistance.Highlights PANI‐Cu‐MOF composite is embedded to VE resin as novel anti‐corrosive pigment. The highest Rcoat are achieved for VE‐PANI‐Cu‐MOF 0.5 wt. %. In the presence of PANI‐Cu‐MOF, the corrosive species penetrations decreased.

Self‐Assembly of UiO‐66 on Conjugated Polyelectrolytes: Toward Enhanced Photophysical Properties

AbstractIn this study, the synthesis and characterization of the fluorescent metal–organic framework (MOF)‐polymer composites is reported based on zirconium‐based MOFs (UiO‐66 and UiO‐66(OH)₂) and a conjugated polyelectrolyte, poly(phenylene ethynylene) carboxylate (PPE‐CO₂‐108). The defect‐rich nature of these Zr‐MOFs facilitates strong interactions between the polyelectrolyte's carboxylic acid moieties and the open metal sites on the Zr clusters within the MOF nanoparticles. The composites are prepared by a simple impregnation approach, where MOF nanocrystals suspended in HEPES buffer are added to the polymeric solution under sonication for 10 min. The obtained MOF composites (i.e., UiO‐66‐CPE and UiO‐66 (OH)2‐CPE) are characterized using powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer‐Emmett‐Teller (BET) surface area, zeta potential measurements, and UV–vis spectroscopy. The characterization confirmed the homogeneous distribution of the MOF nanocrystals on the polymer as seen in the SEM images, and the interaction with PPE‐CO₂‐108 is confirmed by the decrease in the surface areas from 1050 to 590 m2 g−1 for UiO‐66‐CPE and from 500 to 137 m2 g−1, for UiO‐66(OH)2‐CPE. Fluorescence microscopy revealed strong fluorescence in the microparticles, confirming robust polymer‐MOF interaction. The composites also exhibit improved photostability of the conjugated polyelectrolyte, suggesting their potential for applications in biomedical imaging and other areas requiring stable and bright fluorescent systems.

Electrodeposited Pt nanoparticles loaded on support composites of metal-organic frameworks and carbon quantum dots for the enhancement of alcohol electrooxidation

Metal-organic frameworks comprising divalent metal (M)-linked 4,4′-bipyridine (bpy), {[CuII4(bpy)3(OH)2(mal)3]·4H2O}n(Cubpy) and Ni2(bpy)3(NO3)4(H2O)4(Nibpy) were modified with carbon quantum dots (Mbpy/CQD; M = Cu, Ni) to prepare a composite support. Then, platinum (Pt) nanoparticles were electrodeposited onto the modified Mbpy/CQD support for the preparation of Pt-based catalysts (Pt/Mbpy/CQD) for the electrocatalytic improvement of alcohol oxidation. The influence of Mbpy with electrodeposited Pt nanostructures on CQD support electrodes is particularly discussed in detail through numerous physical characterizations, e.g., SEM, TEM, EDX, XPS, XRD, and elemental mapping. Dispersed Pt nanoparticles with diameters of 3-10 nm can be obtained on the modified Mbpy/CQD supports with suitable chemical and structural conditions for electrocatalytic oxidation improvement. The various prepared Pt/Mbpy/CQD catalysts with different compositions also enhance the kinetics of alcohol oxidation; they have a greater electrochemically active surface area (ECSA) and more development activity for alcohol oxidation than do the Pt/CQD catalysts. For the oxidation of all the selected small alcohol molecules, e.g., methanol, ethanol and isopropanol, the Pt/Cubpy/CQD catalyst composites also mostly exhibited improved catalytic activity, outstanding stability, and lower onset potential (Eonset) and CO tolerance. The favorable performance of the prepared composite catalysts is attributed to their superior ECSA owing to the suitable mixed surface of metal and functional groups of electrodeposited Pt, Mbpy, and CQD on the catalytic composites. Consequently, these as-prepared Pt/Mbpy/CQD composites, which are promising oxidative heterogeneous catalysts, can be used as active and stable catalysts for alcohol oxidation in alkaline solutions.

Magnetic graphene oxide grafted boronic acid-decorated metal-organic frameworks for selective enrichment of cis-diol-containing nucleosides

In this study, a novel magnetic graphene oxide grafted boronic acid-decorated metal-organic frameworks (Fe3O4@GO@BA-MOF) composite was developed for the selective enrichment of cis-diol-containing nucleosides. It is noteworthy that the amino-functionalized Fe3O4 was prepared by polyethyleneimine (PEI) as modifier, resulting in excellent durability and stability of magnetic nanoparticles under different environment, as well as introducing rich active functional groups for post-modification. GO with large surface area and abundant multi-active group was covalently bonded on amino-rich Fe3O4 as interlayer to facilitate the growth of BA-MOF with high boronic acid grafting density for selective capture of nucleosides. Due to the multi-interactions, especially the boronate affinity as well as the synergistic effect, the Fe3O4@GO@BA-MOF composite exhibited superior selectivity and adsorption capacity to nucleosides. Under the optimal conditions, an efficient magnetic solid-phase extraction-high-performance liquid chromatography technique was established using Fe3O4@GO@BA-MOF composite for the purpose of extracting and detecting nucleosides in urine, with recoveries ranging from 90.69 % to 110.36 %, relative standard deviations below 8.5 % and detection limits ranging from 0.004 to 0.010 μg mL−1. This study offers a new approach for preparation of high grafting density of boronic acid-decorated magnetic MOF, which is promising in selective enrichment of cis-diol-containing compounds in biological analysis.

Zirconium-based metal-organic framework composites for solid phase extraction of brevetoxin-A from seawater

Red tides are a type of natural marine disaster caused by harmful algae characterized by a high toxicity, wide distribution, and long duration. Since the concentration of algal toxins in seawater increases with the occurrence of red tides, algal toxins detected in seawater could be used to predict the occurrence and evolution of red tides. Brevetoxin-A (BTX-A) is a secondary metabolite produced by the harmful algae Karenia brevis, whose detection in seawater could form the basis of an accurate warning system for incoming red tides. However, due to the inherent complexity of the seawater matrix and the extremely low levels of BTX-A in seawater, the use of instruments for its direct detection is difficult. Therefore, there is an urgent need to develop a sample pretreatment method for the efficient enrichment of BTX-A in seawater. In this study, a metal-organic backbone material (UiO-66) and its composite with silica microspheres (SiO2@UiO-66) were successfully synthesized using the solvothermal method. The prepared SiO2@UiO-66 exhibited good hydrophilicity, water stability, and large specific surface area. Furthermore, it also exhibited hydrogen bonding and electrostatic interactions with BTX-A, had a strong affinity for BTX-A, and was able to efficiently adsorb BTX-A in complex matrices. Therefore, SiO2@UiO-66 showed potential as a novel packing material for the extraction of BTX-A from solid phase extraction columns. Combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), a highly sensitive detection method for the determination of BTX-A in marine water was established. The established analytical method had a low detection limit (3.0 pg/mL), a wide linear range (10.0 -200.0 pg/mL), and a good linear relationship (R=0.9992). Combined with the Fujian Province Red Tide Monitoring and Early Warning Information 2021 issued by the Fujian Provincial Oceanic and Fisheries Bureau, the analytical method established herein was successfully applied to analyze and monitor the content of BTX-A in actual seawater samples. This highlights the proposed system's potential for use as an early warning factor in the monitoring of red tides, representing a simple and fast pretreatment methodology for the detection of BTX-A in seawater.

Engineering modulation of cellulose-induced metal–organic frameworks assembly behavior for advanced adsorption and separation

The exploration of methods to remove harmful pollutants has become inevitable due to the increasing number of industries and the intensification and acceleration of environmental pollution. Therefore, the development of effective adsorption and separation process technologies is essential to ensure environmental remediation. Metal-organic framework (MOF) has attracted great attention in adsorption and separation area due to its large porosity, large specific surface area, tunable pore structure, and high chemical and thermal stability. However, the powder state of MOF results in weak flexibility, manufacturability, and recyclability, severely limiting its application. In this case, the synthesis of MOF composites by in-situ or ex-situ growth with abundant and sustainable cellulose family materials is an effective strategy for stabilizing these MOF species, modulating the assembly behavior of MOF, and expanding the forms of MOF application. Particularly, exciting research activities have emerged ranging from fabrication strategies for cellulose/MOF composites to adsorption and separation applications. In this review, the recent advances in cellulose/MOF composites regarding assembly methods, processing strategies, and adsorption and separation areas are comprehensively summarized. Meanwhile, focusing on the design concept of using cellulose to regulate the assembly behavior of MOF to construct macrostructures, the property characteristics and design principles of cellulose/MOF composites are deeply analyzed with examples. Moreover, the crucial challenges and future perspectives are also meticulously analyzed and discussed. We sincerely hope this review can further promote the research enthusiasm for cellulose/MOF composites in adsorption and separation applications and provide useful references for the design and application strategies of cellulose/MOF.

Fabrication of metal‐organic frameworks macro-structures for adsorption applications in water treatment: A review

Metal-organic frameworks (MOFs) are emerging porous organic–inorganic hybrid materials composed of metal centers/clusters and various organic ligands, which are widely used in water and wastewater treatment applications due to their large specific surface area, high porosity, tunable chemical properties and abundant active sites. However, pure MOFs powders have limitations such as poor recovery, blocked pipelines and secondary contamination in practical water treatment processes. Enabling the magnetization of MOFs or immobilizing MOFs as macroscopic MOFs materials offers new opportunities to improve solid–liquid separation performances of powdered MOFs. Besides, macroscopic MOFs materials with outstanding adsorption performance and mechanical properties by the combining of 3D particles and 2D nanosheets MOFs with other substrates are widely used for water treatment. This paper provides a comprehensive review of recent advancements in MOFs macro-structures. We firstly summarized the synthesis strategies of magnetic MOFs composites and various MOFs macro-structures such as hydrogels/aerogels, membranes, beads/spheres, others composites, etc. which can be constructed by various methods, including in-situ growth, solvothermal method, direct mixing, self-assembly, layer-by-layer growth, etc. Innovative preparation strategies to improve the mechanical properties of MOFs macro-structures were highlighted. Next the article discusses its application for adsorptive removal of various pollutants (i.e., dyes, heavy metal ions, oils and organic pollutants) from water. Finally, the challenges of macroscopic MOFs materials and their practical applications are presented, while future research directions to overcome these existing limitations are also pointed out.

Construction of AgI/NH2-MIL-125(Ti) heterojunction: Efficient degradation of organic pollutants in water by visible light response

Photocatalytic technology is an effective means to convert clean solar energy into green chemical energy, which has broad application prospects. Metal-organic framework (MOFs) composites have been widely used to remove pollutants from water. In this paper, the photocatalytic effect of NH2-MIL-125(Ti)[NM125(Ti)] photocatalyst with different AgI content on pollutants in water under visible light irradiation were studied. The successful preparation of AgI/NH2-MIL-125(Ti) photocatalyst was proved by the characterization of the physical and chemical structure of the composite material. When the dosage of AgI is 0.5 mmol, the removal rate of TC by AgI/NH2-MIL-125(Ti) is the highest (82 %). In addition, the photoelectrochemical test also proved that AMNT-0.5 mmol photocatalyst has higher electron-hole separation efficiency. After five cycle tests, the composite photocatalyst of ANMT-0.5 mmol still has good stability. The enhancement of the performance of ANMT-0.5 mmol photocatalyst can be attributed to: (i) the introduction of AgI increases the absorption of visible light in the composite; (ii) The close relationship between AgI and NM125(Ti) accelerates the separation of electron-hole pairs, thus improving the photocatalytic performance.

Recent research progress of MOFs-based heterostructures for photocatalytic hydrogen evolution

The growing serious energy crisis and environmental pollution expedite the development of green hydrogen energy. Photocatalytic water splitting technology, converting solar energy into chemical energy directly, provides a clean and economical way for hydrogen evolution. For the past few years, metal–organic frameworks (MOFs) semiconductor materials have become a research hotspot in the field of photocatalytic hydrogen evolution (PHE) due to their multiple advantages, including adjustable structure, high porosity, large specific surface area, abundant active sites, and so forth. Besides this, the construction of heterogeneous structures based on MOFs materials can further improve PHE performance through the effective internal electric field directional transfer of photogenerated electrons and the superior utilization rate of sunlight in comparison to the single MOFs photocatalyst. Herein, in this minireview, we summed up the varieties of synthesis methods of diverse types of MOFs heterojunction complex materials, discussed the H2 evolution efficiency based on this heterostructure photocatalyst in detail, and lastly proposed the advantages, limitations, and outlook of MOFs composites in the PHE field. We sincerely hope this review can provide a reference for future research based on MOFs materials for alleviating the current energy crisis.

Development of a Multiparticulate Metal-Organic Framework/Textile Fiber Swatch.

The versatility of metal-organic frameworks (MOFs) has led to groundbreaking applications in a wide variety of fields, especially in the areas of energy, environment, and sustainability. For example, MOFs can be designed for high uptake of toxic gases and pollutants, such as CO2, NH3, and SO2, but designing a single MOF that shows tangible uptake for all of these gases is challenging due to the differences in the chemical and physical properties of these molecules. To this end, integrating multiple MOFs onto textile fibers and crafting various structures have emerged as pivotal developments, enhancing framework durability and usability. MOF composites prepared on readily available textile fibers offer the flexibility essential for critical applications, including heterogeneous catalysis, chemical sensing, toxic gas adsorption, and drug delivery, while preserving the unique characteristics of MOFs. This study introduces a scalable and adaptable method for seamlessly embedding multiple high-performing MOFs onto a single textile fiber using a dip-coating method. We explored the uptake capacity of these multi-MOF composites for CO2, NH3, and SO2 and observed a performance similar to that of traditional powdered materials. Along with harmful gas adsorption, we also have evaluated the permeation and reactivity of these MOF/textile composites toward chemical warfare agents (CWAs) like GD (soman), HD (mustard gas), and VX. In combination, these results demonstrate a fundamental advancement toward establishing a consistent strategy for the hydrolysis of nerve agents in real-world scenarios. This approach can substantially increase the protection toward CWAs and enhance the effectiveness of protective equipment such as fabrics for protective garments. This dip-coating method for the integration of multiple MOFs on a single textile fiber unlocks a wealth of possibilities and paves the way for future innovations in the deployment of MOF-based composites.

An ultrasound assisted dispersive micro solid-phase extraction and a composite ionic liquid-metal organic framework for sixteen polycyclic aromatic hydrocarbons analysis in fruit juice and environmental water samples

Aluminum-based metal organic framework composite containing ionic liquid was prepared and used as sorbent for extraction of sixteen polycyclic aromatic hydrocarbons in list of priority pollutants of United States Environmental Protection Agency before their analysis by gas chromatography/mass spectrometry. The dispersive micro solid-phase extraction method, known as a simple and fast method, was preferred as the extraction method. The optimized parameter conditions were 5 mL of sample solution, 10 min sonication by ultrasonic bath, 30 mg of sorbent, 30 °C extraction temperature, 0.1 mL of hexane as elution solvent with 5 min elution time. The suggested method presented that limit of detection and limit of quantification were in the range of 0.01–0.10 μg l-1, and 0.04–0.33 μg L-1, respectively. The intra-day and inter-day repeatability were within the ranges of 1.18–4.88 % and 1.02–5.06 %, respectively. The recoveries for polycyclic aromatic hydrocarbons in peach juice, cherry juice, tap water and rain water samples were obtained in the range of 84.9–99.9 % for spiked 5, 50 and 100 μg l-1 standard polycyclic aromatic hydrocarbons solution.

Metal-Organic Framework-Based Materials for Heavy Metal Sensing in Aqueous Media

Industrial development leads to an increasing amount of pollutants including heavy metal ions in surface and subsurface waters. For instance, wastewater from battery manufacturing, paint manufacturing or metal plating, contain heavy metals in high concentrations. The heavy metals are typically non-biodegradable and not-easy to excrete. Their presence within the organisms causes damage and failure of different organs. Consequently, the permissible concentrations of heavy metal ions in drinking water set by the World Health Organization are on a ppb level.In this work, electrode materials based on metal-organic frameworks (MOFs) are prepared and studied for sensing of heavy metals in aqueous media. These involved MOFs in their pristine form, composites of pristine MOFs and conducting polymer polyaniline as well as their carbonized derivatives. Cadmium and lead ions were used as model pollutants. Thorough physico-chemical characterization of the prepared materials was done using scanning electron microscopy, Raman spectroscopy, and dynamic light scattering. Electroanalytical performance was scrutinized using anodic stripping voltammetry and correlated with materials’ structural, morphology and textural properties. Limits of detection and sensitivity were determined upon optimization of the experimental conditions to identify the best material. Moreover, materials proved to be suitable for two heavy metal ions sensing in real river samples. Acknowledgments This work was supported by the Science Fund of the Republic of Serbia, grant number 7750219, Advanced Conducting Polymer-Based Materials for Electrochemical Energy Conversion and Storage, Sensors and Environmental Protection-AdConPolyMat (IDEAS programme).

Crystalline Metal-Organic Framework Coatings Engineered via Metal-Phenolic Network Interfaces.

Crystalline metal-organic frameworks (MOFs) have garnered extensive attention owing to their highly ordered porous structure and physicochemical properties. However, their practical application often requires their integration with various substrates, which is challenging because of their weakly adhesive nature and the diversity of substrates that exhibit different properties. Herein, we report the use of amorphous metal-phenolic network coatings to facilitate the growth of crystalline MOF coatings on various particle and planar substrates. Crystalline MOFs with different metal ions and morphologies were successfully deposited on substrates (13 types) of varying sizes, shapes, and surface chemistries. Furthermore, the physicochemical properties of the coated crystalline MOFs (e.g., composition, thickness) could be tuned using different synthesis conditions. The engineered MOF-coated membranes demonstrated excellent liquid and gas separation performance, exhibiting a high H2 permeance of 63200 GPU and a H2/CH4 selectivity of 10.19, likely attributable to the thin nature of the coating (~180 nm). Considering the vast array of MOFs available (>90,000) and the diversity of substrates, this work is expected to pave the way for creating a wide range of MOF composites and coatings with potential applications in diverse fields.