MOF Composites Research Articles

Synthesis and characterization of MOF polymer nanocomposites for Chromium adsorption and their antimicrobial properties

This study describes the preparation of MOF and its polymer composites, namely Co@BTC(MOF1), Co@BTC(PAA)(MOF2), and Co@BTC(PAA)(CTAB)(MOF3), by assimilating cobalt nitrate hexahydrate [(CoNO3)2·6H2O] with trimesic acid, polyacrylic acid (PAA), and cetyltrimethylammonium bromide (CTAB) using a solvothermal procedure at 100℃ for 12 h. All MOF composites exhibited remarkable adsorption properties and thermal and chemical stability properties. These polymer composite MOFs are explored for the adsorption of anionic dyes such as Methyl Orange (MO) and Congo Red (CR), cationic dye Methylene Blue (MB), and Chromium (VI) from wastewater. A 90–95 % adsorption rate for MO and CR dyes was observed within 60 min using 100 mg of MOF composites. Within 60 min, the MOF composites achieved an adsorption rate of 90–95 % for MO and CR dyes when 100 mg of the composites were used. Furthermore, MOF2 and MOF3 have exhibited a remarkable 92 % efficiency in adsorbing Cr(VI) during one hour, following a pseudo-second-order kinetic model. The composites were examined for their anti-bacterial efficacy against Bacillus (Gram-positive), E. Coli (Gram-negative), and Saccharomyces cerevisiae. The results were compared to ciprofloxacin, a conventional antibiotic, using the agar diffusion method. MOF2 and MOF3 have demonstrated long-lasting and potent antimicrobial activity, successfully inhibiting the growth of bacteria for a period of at least 90 days. Furthermore, the polymer composites of MOFs exhibit notable capability in scavenging radicals, particularly against ascorbic acid, as determined by the DPPH method. The inhibition rates for the composites are 68.7 % and 65.9 %, respectively. This indicates that these polymer MOF composites possess potent anti-microbial activity, making them an ideal candidate for addressing the inhibition of bacterial growth.

Stabilizing Ni2+ in Hollow Nano MOF/Polymetallic Phosphides Composites for Enhanced Electrochemical Performance in 3D-Printed Micro-Supercapacitors.

Polymetallic phosphides exhibit favorable conductivities. A reasonable design of nano-metal-organic frame (MOF) composite morphologies and in situ introduction of polymetallic phosphides into the framework can effectively improve electrolyte penetration and rapid electron transfer. To address existing challenges, Ni, with a strong coordination ability with N, is introduced to partially replace Co in nano-Co-MOF composite. The hollow nanostructure is stabilized through CoNi bimetallic coordination and low-temperature controllable polymetallic phosphide generation rate. The Ni, Co, and P atoms, generated during reduction, effectively enhance electron transfer rate within the framework. X-ray absorption fine structure (XAFS) characterization results further confirm the existence of Ni-N, Ni-Ni, and Co-Co structures in the nanocomposite. The changes in each component during the charge-discharge process of the electrochemical reactions are investigated using in situ X-ray diffraction (XRD). Theoretical calculations further confirm that P can effectively improve conductivity. VZNPGC//MXene MSCs, constructed with active materials derived from the hollow nano MOF composites synthesized through the Ni2+ stabilization strategy, demonstrate a specific capacitance of 1184 mF cm-2, along with an energy density of 236.75 µWh cm-2 (power density of 0.14 mW cm-2). This approach introduces a new direction for the synthesis of highly conductive nano-MOF composites.

Three-in-one novel flame retardant through grafting organophosphorus onto Fe-MOF functionalized Mg(OH)2 for improving fire safety and mechanical properties of PBS composites

As one typically sustainable polymer material, poly(butylene succinate) (PBS) is highly necessary to improve its flame retardancy and simultaneously maintain satisfied mechanical performances. In this study, “three-in-one” novel flame retardant was synthesized through grafting organophosphorus onto Fe-MOF functionalized Mg(OH)2 (labeled as MH@Fe-MOF-P), then it was introduced into PBS matrix to investigate its effect on flame retardancy and mechanical properties. The results indicated that PBS/20MH@Fe-MOF-P exhibited excellent flame retardancy, including that the LOI was 29.6%, the UL-94 rating reached to V0, and the peak of heat release rate (PHRR) decreased by 82.1%. The flame retardant mechanism was ascribed to the synergistic effect of Mg(OH)2, Fe-MOF and organophosphorus on delaying the decomposition and catalyzing the carbonization of PBS. Meanwhile, PBS/20MH@Fe-MOF-P presented better mechanical performances than PBS/20MH and PBS/20MH@Fe-MOF composites, resulting from the special structure of MH@Fe-MOF-P to achieve good dispersion of fillers and strong polymer-filler interface adhesion. This work provides a novel strategy to modify Mg(OH)2 with high flame retardant efficiency, and also broadens the practical applications of PBS materials with balanced comprehensive performances.

Nano Metal–Organic Frameworks as Advanced Electrode Materials in Electrochemical Energy Storage

AbstractNano metal–organic frameworks as an attractive new class of porous materials, are synthesized via metal ions and organic ligands. With their desirable properties of abundant pores, high specific surface areas, fully exposed active sites and controllable structures, nano MOFs are acknowledged to be one of the most vital materials in electrochemical energy storages. However, in their practical applications, nano MOFs are still confronted with various difficulties and challenges because of their low conductivity, poor stability, and other disadvantages. The selection and development of MOF composites, MOF–derived materials and modified MOFs might be beneficial to use as better electrode materials to greatly improve the electrochemical properties of energy storage devices. This paper mainly focuses on the recent developments of nano MOFs as prospective materials in electrochemical energy storage applications, including lithium–ion batteries (LIB), lithium–sulfur batteries (LSB), zinc–ion batteries (ZIB), and supercapacitors (SCs). Finally, the challenges faced by these kinds of energy storage devices are proposed, along with the current directions and prospect.

In-situ synthesis of ZIF-8 on magnetic pineapple leaf biochar as an efficient and reusable adsorbent for methylene blue removal from wastewater.

The presence of organic dyes in aquatic systems poses a significant threat to ecosystems and human well-being. Due to recycling challenges, traditional commercial activated carbon is not cost-effective. To address this, an imidazolate acid zeolite framework-8 (ZIF-8)-modified magnetic adsorbent (ZMPLB-800) was synthesized through the in-situ formation of ZIF-8 and subsequent carbonization at 800 °C, using magnetic pineapple leaf biochar (MPLB) as a carrier. The porous structure of ZMPLB-800 facilitates the rapid passage of dye molecules, enhancing adsorption performance. ZMPLB-800 exhibited remarkable adsorption capacity for methylene blue (MB) across a pH range of 3-13, with a maximum adsorption capacity of 455.98mg g-1. Adsorption kinetics and thermodynamics followed the pseudo-second-order kinetic model and Langmuir isotherm model. Mechanisms of MB adsorption included pore filling, hydrogen bonding, electrostatic interactions, π-π interactions, and complexation through surface functional groups. Additionally, ZMPLB-800 demonstrated excellent regeneration performance, recording a removal efficiency exceeding 87% even after five adsorption/desorption cycles. This study provides a novel strategy for treating dye wastewater with MOF composites, laying the foundation for waste biomass utilization.

Construction of raspberry-like molecularly imprinted polymers based on MOF composites for selective extraction of sinapic acid from agricultural waste

Efficient and selective extraction of valuable sinapic acid from agricultural by-products is desirable. A novel raspberry-shaped imprinted polymers (CN@UiO-66-C=C@MIPs) based on in-situ generated Metal Organic Frameworks composites were fabricated for high-efficient and selective enrichment of sinapic acid from squeezed rapeseed meal. By incorporating well-distributed MOF particles and template immobilization strategy in surface imprinting technology, CN@UiO-66-C=C@MIPs exhibit a high specific surface area of 275 m2/g, with an average pore diameter of 2.78 nm. The high-efficient CN@UiO-66-C=C@MIPs showed fast kinetic equilibrium time (10 min), high adsorption capacity (141.3 mg g−1), and good selectivity (IF = 3.29) towards sinapic acid. Furthermore, sinapic acid imprinted CN@UiO-66-C=C@MIPs has satisfactory stability after sonication for 6.0 h and benign regeneration property after repeatedly used for 8 times. Therefore, CN@UiO-66-C=C@MIPs could be an ideal adsorbent with sufficient feasibility for selective extraction of sinapic acid from complex natural samples.

Multi-point immobilization of GH 11 endo-β-1,4-xylanase on magnetic MOF composites for higher yield of xylo-oligosaccharides

GH 11 endo-β-1,4-xylanase (Xy) was a crucial enzyme for xylooligosaccharides (XOS) production. The lower reusability and higher cost of purification has limited the industrial application of Xy. Addressing these challenges, our study utilized various immobilization techniques, different supports and forces for Xy immobilization. This study presents a new method in the development of Fe3O4@PDA@MOF-Xy which is immobilized via multi-point interaction forces, demonstrating a significant advancement in protein loading capacity (80.67 mg/g), and exhibiting remarkable tolerance to acidic and alkaline conditions. This method significantly improved Xy reusability and efficiency for industrial applications, maintaining 60 % activity over 10 cycles. Approximately 23 % XOS production was achieved by Fe3O4@PDA@MOF-Xy. Moreover, the yield of XOS from cobcorn xylan using this system was 1.15 times higher than that of the free enzyme system. These results provide a theoretical and applicative basis for enzyme immobilization and XOS industrial production.

A novel electrochemiluminescence biosensor based on Ru(bpy)32+-functionalized MOF composites and cycle amplification technology of DNAzyme walker for ultrasensitive detection of kanamycin

An electrochemiluminescence (ECL) sensing platform for ultrasensitive and highly selective detection of kanamycin (KANA) was developed based on the prepared Ru(bpy)32+-functionalized MOF (Ru@MOF) composites by hydrothermal synthesis and Ag+-dependent DNAzyme. In this sensor, the stem-loop DNA (HP) with the ferrocene (Fc) was used as substrate chain to quench the ECL emission generated by the Ru@MOF. Using the specific recognition effect between KANA and the KANA aptamer (Apt) and the DNAzyme dependence on Ag+, the KANA aptamer as the pendant strand of the DNAzyme was assembled on Ru@MOF/GCE with the aptamer. When both Ag+ and KANA were present simultaneously, KANA specifically was binded to KANA aptamer as a pendant chain. Subsequently, Ag+-dependent DNAzyme walker continuously cleaved the HP chain and released the modified end of Fc to restore the ECL signal of Ru@MOF composites, thus achieving selective and ultrasensitive detection of KANA. The constructed KANA biosensor exhibits a wide detection range (30 pM to 300 μM) accompanied by a low detection limit (13.7 pM). The KANA in seawater and milk samples are determined to evalute the practical application results of the sensor. This ECL detection strategy could be used for detecting other similar analytes and has broad potential application in biological analysis.

Efficient desulfurization of light crude oil using MOF and its composite

High sulfur content in petroleum fuels is a critical concern due to its significant contribution to environmental pollution through the formation of sulfur oxides during combustion. These sulfur compound not only degrade the quality of the fuel and quantity of finished petrochemical products, but also adversely affect the environment and damage equipment, tanks and pipelines. To address these issues and meet the rising need for both cleaner fuels and high-valued petrochemical products, desulphurization has become a key focus in crude oil refining. In this study, a MOF composite, ZIF-8/Co with montmorillonite clay was fabricated and tested for the desulfurization of light crude oil (LCO). For the first time, this composite adsorbent was applied to real crude oil system, achieving an impressive sulfur removal efficiency of 58.9%. The use of a green synthesis method further emphasizes the sustainability and cost effectiveness of this approach, presenting a promising advancement in crude oil desulfurization technology.

Engineering a pyrene MOF composite photocatalyst toward the formation of carbon dioxide radical anions through regulating the charge transfer from type II to Z scheme via a chemical bond-modulated strategy

A new approach was reported for regulating the charge transfer mechanism in a pyrene-based MOF composite, transitioning from a type-II to a Z-scheme configuration.

A novel chemiluminescence sensor for alpha-fetoprotein detection based on an aptamer-luminol modified magnetic graphene oxide and copper-based MOF composite.

Herein, an aptamer-luminol modified magnetic graphene oxide and copper-based MOF composite was prepared and used to build a novel target-triggered "turn on" chemiluminescence (CL) sensor for alpha-fetoprotein (AFP) detection. Magnetic graphene oxide (MGO) was functionalized with the complementary sequence of the AFP aptamer (cDNA), and then MGO-cDNA was linked to aptamer modified luminol (Apt-luminol) through the complementary base pairing effect. The functionalized magnetic graphene oxide (MGO-cDNA/Apt-luminol) was prepared as a specific magnetic separation and signal switch material. ZnONPs-Au@CuMOFs shows excellent catalytic performance and was used as a catalyst for the luminol-H2O2 reaction. AFP will specifically recognize and bind to Apt on MGO-cDNA/Apt-luminol when AFP is present, which causes luminol release and triggers the CL reaction. The released luminol encounters ZnONPs-Au@CuMOFs and produces strong CL intensity. Therefore, a novel target-triggered "turn on" CL method with high selectivity and sensitivity for detecting AFP has been established. The linear range and detection limit were 1.0 × 10-4-50 ng mL-1 and 4.2 × 10-5 ng mL-1, respectively. The sensor also exhibited good selectivity, reproducibility and stability, and was finally used for AFP detection in serum samples.

Ultrasonic-assisted in situ synthesis of MOF-199 on the surface of carboxylated cellulose fibers for efficient adsorption of methylene blue.

A high-efficiency porous adsorbent, MOF-199/carboxylated cellulose fibers (MOF-199/CCF), was synthesized in situ at room temperature through carboxylation modification, simple sonication, and vacuum drying. The sonication method produced small MOF-199 particles (tens of nanometers), which allowed for uniform distribution of MOF-199 on CCF and improved its efficiency. The presence of CCF carriers reduces the agglomeration of MOF-199 and enhances its performance. The BET-specific surface area of MOF-199/CCF is 264.83 m2 g-1, which is much larger than that of CCF (2.31 m2 g-1), proving the successful modification of CCF by MOF-199. MOF-199/CCF exhibits better adsorption capacity than CCF, with an adsorption capacity of 659.6 mg g-1 of methylene blue within 30 minutes, and good recycling performance. This work presents a straightforward method for preparing efficient cellulose-based adsorbent materials and offers a novel approach for synthesizing MOF composites.

Hybridization of magnetic MOF composites with 3D terminal carboxyl hyperbranched polymers for dye wastewater treatment

A novel adsorbent obtained by hybridization of magnetic MOFs with three-dimensional terminal carboxyl hyperbranched polymers to achieve efficient dye removal.

Preparation of sulfur–MOF composites and their application in the Willgerodt–Kindler reaction

A convenient MOF-assisted solvent-free protocol for Willgerodt–Kindler reaction with a reusable sulfur carrier is demonstrated.

Sustainable and shaped synthesis of MOF composites using PET waste for efficient phosphate removal

Schematic illustration of the sustainable synthesis of different MOFs using PET waste and the shaping of Fe-MOF into Fe-MOF@PET composite chips for efficient recovery and recycling processes after the removal of phosphate from water.

Chemical shaping of CPO-27-M (M = Co, Ni) through an in situ crystallization within chitosan hydrogels.

The preparation of MOF composites is considered as an effective method to address the challenges of shaping MOFs and to create porous solids with enhanced properties and broader applications. In this study, CPO-27-Co was crystallized via a simple strategy within porous chitosan beads. The resulting CS@CPO-27-Co composites were tested for CO2 sorption and they demonstrated promising performances by exceeding 3 mmol(CO2) g-1. The versatility of this strategy was further demonstrated by replacing cobalt(II) ions with nickel(II), also leading to the isostructural CPO-27 framework.

Ultra-sensitive electrochemical sensors through self-assembled MOF composites for the simultaneous detection of multiple heavy metal ions in food samples

Using an assemble-able MOF material, we successfully constructed an ultra-sensitive electrochemical sensor based on Bi2CuO4@Al-MOF@UiO-67 nanocomposite material, in order to investigate the adsorption properties of the Bi2CuO4@Al-MOF@UiO-67 functional material on the heavy metal ion. The Cd2+, Cu2+, Pb2+ and Hg2+ can be detected at the same time. Selective recognition and enrichment of various metal ions on different substrates can be achieved through the assembly of a large number of Al-MOF and UiO-67-MOF nanomaterial composites with small particle sizes on the Bi2CuO4 surface. Based on this, a new type of sensor is researched and prepared, which has been shown to have good stability and reproducibility. Due to its unique assembly structure, large active surface area, excellent adsorption capacity, and high electrical conductivity, Bi2CuO4@Al-MOF@UiO-67 presents outstanding performance. In addition, the sensor also exhibits excellent electrocatalytic redox capacity and high selectivity. The adsorption capacity of Cd2+, Cu2+, Pb2+ and Hg2+ is also significantly improved under the action of the sensor electrode, however, this is not the case. The limits of detection for Cd2+, Cu2+, Pb2+ and Hg2+ were found to be 0.02 pM, 0.032 pM, 0.018 pM and 0.041 pM, respectively. In order to investigate the detection mechanism of Cd2+, Cu2+, Pb2+ and Hg2+ was adsorption properties as well as electrochemical accumulation of Bi2CuO4@Al-MOF@UiO-67 on the metal atoms were investigated. This method has been successfully applied to samples of rice, sorghum, maize, milk, honey, and tea, and has enabled the simultaneous detection of Cd2+, Cu2+, Pb2+ and Hg2+, which is of significant practical value.

Facile fabrication of binary g-C3N4/NH2-MIL-125(Ti) MOF nanocomposite with Z-scheme heterojunction for efficient photocatalytic H2 production and CO2 reduction under visible light

A binary g-C3N4/NH2-MIL-125(Ti) MOF nanocomposite was fabricated through a facile sonochemical-assisted thermal approach for enhanced photocatalytic H2 production and CO2 reduction under visible light. Compared to pure g-C3N4, the g-C3N4/MOF photocatalyst showed enhanced visible light absorption with promoted charge carrier separation which increased the H2 production rate and the CO2 reduction into CH4 and CO. This enhancement was attributed to the successfully constructed Z-scheme heterojunction in addition to the visible-active, large surface area and highly CO2 adsorbable NH2-MIL-125(Ti) MOF. The highest H2 production of 480 µmol g−1 was exhibited over the g-C3N4/NH2-MIL-125(Ti) nanocomposite with 20 wt% MOF. Similarly, the highest CO production rate of 338 µmol g−1 was achieved with 20 wt% MOF composite. However, for the CH4 product gas, it was observed that the highest production rate was attained with pure g-C3N4 which reveals the NH2-MIL-125(Ti) MOF selectivity towards CO production instead of CH4. Among all the investigated sacrificial agents for H2 production, methanol was the best. The performance of CO2 reduction process was found to be increasing with the pressure increase. Furthermore, the stability investigations revealed continuous productions of H2, CO and CH4 over the C3N4/MOF photocatalyst in multiple cyclic runswithout any significant photocatalyst deactivation. This study provides new ideas for the fabrication of cheap, efficient and easy-synthesized nanomaterials for energy production and environmental remediation applications.

Robust and highly reactive membranes for continuous disposal of chemical warfare agents: Effects of nanostructure and functionality in MOF and nanochitin aerogel composites

Developing appropriate disposal of stockpiles of chemical warfare agents (CWAs) has gained significant attention as their lethal toxicity seriously harms humanity. In this study, a novel green-fabrication method with UiO-66 catalysts and amine-functionalized chitin nanofibers (ChNFs) was suggested to prepare durable and highly reactive membranes for decomposing chemical warfare agents (CWAs) in the continuous flow system. The strong interaction between ChNFs and the UiO-66 led to stable loading of the UiO-66 on the continuous nano-porous channel of the ChNF reactive membrane even with high loading of UiO-66 (70 wt% of UiO-66 in the ChNF substrate). In addition, the Brønsted base functionalities (–NH2 and –NHCOCH3) of the ChNF enhanced the catalytic activity and recyclability of the UiO-66. The resulting 70-ChNF composites can effectively decompose a nerve agent simulant (methyl paraoxon) even after 7 repeatable cycles, which has been not obtained in the previous UiO-66 catalyst. The ChNF/UiO-66 reactive membranes with 1 m2 of the area decomposed 130 g of CWAs within an hour in a continuous flow system. We believe these robust and highly reactive membranes can provide a sustainable and efficient solution for the massive CWA disposal and also contribute to the advancement of functional membrane material science.

Nanofibers fortified with synergistic defense route: A potent wound dressing against drug-resistant bacterial infections

The escalating utilization of antibiotics and the subsequent evolution of drug resistance among patients have created an urgent imperative to advance antibiotic-free treatment methodologies. In this work, we have developed nanofibrous wound dressings with synergistic antibacterial activity. Our approach involves the layerwise co-assembly of benzalkonium chloride (BC) and metal–organic framework nanoparticles (MOFs, PCN-224) onto poly(ε-caprolactone) (PCL) electrospun nanofibrous membranes (ENMs) using a tannic acid (TA)-assisted adhesion strategy. The electrostatic interaction between the pyrogallol groups of TA and the charged BC under alkaline conditions enables this strategy. Furthermore, the catechol motifs of TA enhance the ENMs' versatility in adhesion and serve as reactive linkers for further co-assembly of PCN-224. The resulting PCL/TA@BC/MOFs (PTM) composites exhibit high loading efficiency of PCN-224, excellent physiological stability, desirable biocompatibility, and synergistic bactericidal therapy. The PTM composites employ dual bacterial defense mechanisms, with PCN-224 converting illumination into singlet oxygen (1O2) for photodynamic effects, while the hydrophobic alkyl chain of BC inhibits bacterial growth by disruption of lipid packing of the bacterial membrane. In vitro and in vivo experiments demonstrate that the PTM composites achieve bactericidal rates exceeding 99.99% against Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA) with only 10 min of irradiation. This breakthrough contributes to the rapid recovery of MRSA-infected wound sites with minimal biological burden. Overall, our rational design of a wound dressing with synergistic bactericidal therapeutic effects presents a novel intervention for enhancing wound disinfection in clinical settings.