Preparation Of Metal-organic Frameworks Research Articles

Magnetic/electric synergy Co@CN/CNTs absorber toward high efficiency electromagnetic waves absorption

Metal-organic framework (MOF) has gained widespread attention as promising electromagnetic waves (EMWs) absorbent due to its 3D structure, porosity and easier modification. However, the structural instability and impedance mismatch presented a serious challenge in meeting the ultra-strong and ultra-broad absorption requirement for EMWs. Therefore, a facile strategy has been applied to prepare carbon nanotubes modified nitrogen-doped carbon encapsulated Co (Co@CN/CNTs) composites by regulating the mass ratio of Co-ZIF67 and melamine under high-temperature pyrolysis. The in-situ synthesis of CNTs and doping of nitrogen-atoms optimized the impedance matching of Co@CN/CNTs composites. The 3D heterostructure, porosity, surface defects and conductive network enhanced EMWs absorption ability. The ultra-strong reflection loss (RL) for Co@CN/CNTs-1:1 sample of −112.14 dB was reached with only 1.3 mm match thickness and corresponding ultra-broad effective absorption bandwidth (EAB) was up to 8.2 GHz. This research could be expected to provide a novel scheme for design and preparation of MOFs derived EMWs absorption materials.

Preparation of metal organic framework by strategy of ligand premodification coupling with dual ligands and adsorption behaviors for organic dyes

The method of ligand premodification coupling with dual ligands to introduce several functional groups can regulate the pore structure of the porous materials to meet different demands and to maintain the integrity of the framework. Amino groups was introduced into organic ligand by reacting with polyethyleneimine and then it was applied as one of the ligands to prepare porous materials. A series of porous materials were synthesized through varying the additional amount of modified ligand and characterized by several techniques such as BET, FTIR, XRD, XPS, SEM and EDS. The prepared materials were then used to remove organic dyes methyl orange (MO), methylene blue (MB) and Congo red (CR) from aqueous solution. The porous materials exhibited larger adsorption capacities and fast adsorption rate for MO and MB as certain modified ligand introduced. Due to steric hindrance of introduced amino chain, the adsorption capacities for CR decreased. The results of adsorption kinetics and adsorption isotherm studies showed that the adsorption process was more in line with pseudo-second kinetic model and Langmuir isotherm. The adsorption selectivity of the material for MB compared to MO could be controlled by altering the amount of modified ligand The prepared porous materials can be used as fascinating adsorbents for removal of dyes from aqueous solution in a wide pH range, and it was attractive and useful from practical viewpoint.

Advancing wastewater treatment and metal recovery: Aminated ZIF-8 composite cellulose aerogel as an innovative biomass adsorbent for enhanced molybdenum ion adsorption

Biomass adsorbents possess significant potential for both metal recovery from industrial leaching solutions and wastewater treatment. However, standalone biomass materials suffer from the drawback of low adsorption capacity. In this study, by the combination of metal–organic frameworks (MOFs) with organic biomaterials, a novel aerogel of aminated ZIF-8 composite cellulose (CPEZN) was developed for molybdenum ions adsorption, and the incorporation of aminated ZIF-8 improved the availability of reactive groups. The unique aerogel structure effectively prevented the accumulation of MOFs, thereby increasing the specific surface area and improving the exposure of active site. In addition, the positively charged surface of CPEZN effectively adsorbed molybdenum ions. Experimental results showed that the introduction of ZIF-8-NH2 improved the adsorption performance of the composites. The adsorption of Mo(VI) followed the Langmuir adsorption isotherm model, and its adsorption rate followed the pseudo-second-order model. The adsorbent exhibited a maximum Mo(VI) adsorption capacity of 872.39 mg/g at pH = 3, and a removal rate of more than 80 % in mixed coexisting ion solutions. Moreover, the adsorbent demonstrated good stability, with a removal rate of above 80 % after 5 cycles of adsorption. Comprehensive characterizations revealed that the adsorption mechanism of Mo(VI) on CPEZN was a synergistic effect of chemisorption, electrostatic interaction, redox, and complex ligand processes. The simulated industrial wastewater adsorption experiment showed that the prepared adsorbent had good removal ability for molybdenum ions. This study not only provides a reference for the design and preparation of MOF and biomass-based composite adsorbent materials, particularly in terms of understanding the adsorption mechanism and designing high-capacity functional groups, but also provides a theoretical basis for its practical application.

An anthraquinone-based bismuth-iron metal-organic framework as an efficient photoanode in photoelectrochemical cells.

Metal-organic frameworks (MOFs) are appealing candidate materials to design new photoelectrodes for use in solar energy conversion because of their modular nature and chemical versatility. However, to date there are few examples of MOFs that can be directly used as photoelectrodes, for which they must be able to afford charge separation upon light absorption, and promote the catalytic dissociation of water molecules, while maintaining structural integrity. Here, we have explored the use of the organic linker anthraquinone-2, 6-disulfonate (2, 6-AQDS) for the preparation of MOFs to be used as photoanodes. Thus, the reaction of 2, 6-AQDS with Bi(iii) or a combination of Bi(iii) and Fe(iii) resulted in two new MOFs, BiPF-10 and BiFePF-15, respectively. They display similar structural features, where the metal elements are disposed in inorganic-layer building units, which are pillared by the organic linkers by coordination bonds through the sulfonic acid groups. We show that the introduction of iron in the structure plays a crucial role for the practical use of the MOFs as a robust photoelectrode in a photoelectrochemical cell, producing as much as 1.23 mmol H2 cm-2 with the use of BiFePF-15 as photoanode. By means of time-resolved and electrochemical impedance spectroscopic studies we have been able to unravel the charge transfer mechanism, which involves the formation of a radical intermediate species, exhibiting a longer-lived lifetime by the presence of the iron-oxo clusters in BiFePF-15 to reduce the charge transfer resistance.

Preparation of metal-organic framework @molecularly imprinted polymers for extracting N-nitrosamines in salted vegetables

In this paper, the novel metal-organic framework @molecularly imprinted polymers were prepared and applied in extracting N-nitrosamines from salted vegetables. The imprinted polymers were coated on the surface of MIL-101 using multi-dummy template molecules (5-nonanol, benzhydrol and N-formylpyrrolidine). The characterization and adsorbing experiments showed that the hybrid imprinted polymers presented spherical particles with typically core-shell structure, and exhibited high adsorption capacity (maximum capacity: 46.85 mg/g) and fast equilibrium rate (only 5 min) for N-nitrosamines. Various parameters (sample loading solvent, pH, washing solvent, elution solvent and elution volume) affecting solid-phase extraction were optimized. Under the optimum conditions, the solid-phase extraction process based on the hybrid polymers combined with high performance liquid chromatography-ultraviolet detection method was established and applied to analyze N-nitrosamines in different salted vegetables. The results showed that the developed method produced the linear relationship between the peak areas versus the N-nitrosamines concentrations of 0.2–10 µg/g with limit of detections from 20.6 to 76.1 ng/g. The spiked recovery of N-nitrosamines in the salted vegetable samples was in the range of 66–100.5 % with relative standard deviation from 0.1 to 3.4 %. Those results demonstrated that the established method was sensitive and efficient for directly enriching and analyzing trace N-nitrosamines in salted vegetables.

Simplifying the Synthesis of Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are porous, crystalline materials constructed from organic linkers and inorganic nodes that have attracted widespread interest due to their permanent porosity and highly modular structures. However, the large volumes of organic solvents and additives, long reaction times, and specialized equipment typically required to synthesize MOFs hinder their widespread adoption in both academia and industry. Recently, our lab has developed several user-friendly methods for the gram-scale (1-100 g) preparation of MOFs. Herein, we summarize our progress in the development of high-concentration solvothermal, mechanochemical, and ionothermal syntheses of MOFs, as well as in minimizing the amount of modulators required to prepare highly crystalline Zr-MOFs. To begin, we detail our work elucidating key features of acid modulation in Zr-MOFs to improve upon current dilute solvothermal syntheses. Choosing an optimal modulator maximizes the crystallinity and porosity of Zr-MOFs while minimizing the quantity of modulator needed, reducing the waste associated with MOF synthesis. By evaluating a range of modulators, we identify the pKa, size, and structural similarity of the modulator to the linker as controlling factors in modulating ability. In the following section, we describe two high-concentration solvothermal methods for the synthesis of Zr-MOFs and demonstrate their generality among a range of frameworks. We also target the M2(dobdc) (M = Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd; dobdc4- = 2,5-dioxido-1,4-benzenedicarboxylate) family of MOFs for high-concentration synthesis and introduce a two-step preparation of several variants that proceeds through a novel kinetic phase. The high-concentration methods we discuss produce MOFs on multi-gram scale with comparable properties to those prepared under traditional dilute solvothermal conditions. Next, to further curtail solvent waste and accelerate reaction times, we discuss the mechanochemical preparation of M2(dobdc) MOFs utilizing liquid amine additives in a planetary ball mill, which we also apply to the synthesis of two related salicylate frameworks. These samples exhibit comparable porosities to traditional dilute solvothermal samples but can be synthesized in just minutes, as opposed to days, and require under 1 mL of liquid additive to prepare ~0.5 g of material. In the following section, we discuss our efforts to avoid specialized equipment and eliminate solvent use entirely by employing ionothermal conditions to prepare a variety of azolate- and salicylate-based MOFs. Simply combining metal chloride (hydrate) salts with organic linkers at temperatures above the melting points of the salts affords high-quality framework materials. Further, ionothermal conditions enable the syntheses of two new Fe(III) M2(dobdc) derivatives that cannot be synthesized under normal solvothermal conditions. Last, as a demonstrative example, we discuss our efforts to synthesize 100 g of high-quality Mg2(dobdc) in a single batch using a high-concentration (1.0 M) hydrothermal synthesis. Our Account will be of significant interest to researchers aiming to prepare gram-scale quantities of MOFs for further study.

Fluoride Removal from Water Sources by Adsorption on MOFs

Fluoride is present in several groundwaters due to natural or anthropogenic origins. Although it is necessary for physiological human functions (in small amounts, i.e., 0.5–1.2 mg/L), it could be very harmful when it exceeds the maximum permissible concentration limit of 1.5 mg/L (according to WHO). Among the numerous technologies for removing fluoride from waters, metal–organic framework (MOF) materials are considered to be promising adsorbents due to their advantages of high porosity, high specific surface area, diverse functions and easy modification. In this study, the synthesis of MOFs and the progress of their application to the removal of fluoride from contaminated water, as published in the recent literature mainly over the past five years, are reviewed. The adsorption mechanism(s) and its main characteristics, such as effect of initial fluoride concentration, adsorbent dosage, solution pH, contact time, adsorption capacity, thermodynamic and regeneration studies, etc., for the removal of fluoride with the addition of different MOFs are compared. According to these comparisons, the hydrothermal/solvothermal synthesis method is most commonly used for the preparation of MOFs, whereas higher BET surface areas are shown by specific MOFs based on aluminum metal ions. The main fluoride adsorption mechanisms were found to be electrostatic attraction and/or complexation. The most common pH for conducting experiments was 7.0, but several examined materials were found to be effective over a wide pH range. Four to six regeneration cycles were successfully applied on average, regarding the MOFs under review, whereas in the majority of these cases, the sorption process was found to be endothermic.

Novel preparation of MOF derived Co(OH)2/ZnFe2O4 magnetic micro-nanoreactor with boost peroxymonosulfate activation for enhanced antibiotic contaminant oxidation

Development of highly efficient and recyclable catalysts based on peroxymonosate (PMS) activation for the degradation of dangerous antibiotic contaminants was still a challenging topic. In this study, a highly efficient and recyclable heterogeneous Co(OH)2/ZnFe2O4 (Co-ZF) catalysts derived from metal-organic frameworks (MOFs) were prepared by a facile alkaline solution hydrothermal method, a high specific surface area (100.4 m2 g−1) and soft magnetic properties (Ms=25.3 emu g−1) composite material was obtained, and used for degrading norfloxacin (NOF) via PMS activation. The effects of temperature, alkali concentration, pH, initial NOF concentration, PMS and catalyst dosage on NOF degradation were discussed in detail. The results illustrated that the degradation rate of norfloxacin by the 3Co-ZF160 catalyst synthesized under 3 M NaOH and 160 ℃ hydrothermal conditions was 97.2%, after four consecutive cycles of degradation, the degradation rate of NOF by 3Co-ZF160 remained over 91% within 60 min. In contrast, the degradation rate of the Co3O4/ZnFe2O4 (CZF-600) catalyst calcined at 600 ℃ was only 74% available. Furthermore, The results of radical quenching suggested that OH•, SO4•−, SO5•− and 1O2 functioned in the presence of the Co(OH)2/ZnFe2O4-PMS system. Eventually, NOF degradation pathways were tentatively proposed on the basis presented via LC-MS. The above results highlight that the practical application of Co(OH)2/ZnFe2O4 heterogeneous catalyst in aqueous solution was of great significance.

Metal-Organic Framework (MOF)-A Universal Material for Biomedicine.

Metal-organic frameworks (MOFs) are a very promising platform for applications in various industries. In recent years, a variety of methods have been developed for the preparation and modification of MOFs, providing a wide range of materials for different applications in life science. Despite the wide range of different MOFs in terms of properties/sizes/chemical nature, they have not found wide application in biomedical practices at present. In this review, we look at the main methods for the preparation of MOFs that can ensure biomedical applications. In addition, we also review the available options for tuning the key parameters, such as size, morphology, and porosity, which are crucial for the use of MOFs in biomedical systems. This review also analyses possible applications for MOFs of different natures. Their high porosity allows the use of MOFs as universal carriers for different therapeutic molecules in the human body. The wide range of chemical species involved in the synthesis of MOFs makes it possible to enhance targeting and prolongation, as well as to create delivery systems that are sensitive to various factors. In addition, we also highlight how injectable, oral, and even ocular delivery systems based on MOFs can be used. The possibility of using MOFs as therapeutic agents and sensitizers in photodynamic, photothermal, and sonodynamic therapy was also reviewed. MOFs have demonstrated high selectivity in various diagnostic systems, making them promising for future applications. The present review aims to systematize the main ways of modifying MOFs, as well as the biomedical applications of various systems based on MOFs.

A versatile microfluidic strategy using air–liquid segmented flow for continuous and efficient synthesis of metal–organic frameworks

Microfluidic synthesis is one of the most state-of-the-art methods for preparing metal–organic frameworks (MOFs) attributed to its high mass/heat transfer efficiency and controllable reaction process. However, the post-processing of the products in most of the currently reported liquid–liquid microfluidic synthesis methods is complicated and can burden the environment due to the using of oil phase. Herein, we report a simple, efficient and versatile method for the preparation of MOFs through an air–liquid segmented flow reaction. Six classical MOFs (HKUST-1, Co-MOF-74, Cu-BDC, MOF-801, UiO-66 and MOF-808) with homogeneous morphologies and different topologies are successfully synthesized by the air–liquid segmented flow method. The prepared A-MOFs exhibited high crystallinity, high space–time yield (STY), homogeneous morphology, smaller particle size, higher surface area compared to the samples synthesized by the solvothermal method, which will benefit the practical applications of MOFs in many fields, such as gas adsorption, catalysis and so on.

Application of metal-organic frameworks-based drug delivery for different diseases treatment

The limitations of traditional drug delivery vehicles include low specificity, uncontrolled biodegradation, and are oftentimes associated with toxicity and serious off-target events. In addressing the biological relevance of an effective drug delivery system in improving the therapeutic efficacy of active ingredients, a variety of new approaches for drug administration have recently been developed. Remarkable breakthroughs following the emergence of nanotechnologies promoted metal-organic frameworks (MOFs) as viable drug delivery possibilities. They are characterised by large surface area and porosities, and hence, exceptional drug adsorption ability. Inorganic MOFs in particular offer high drug loadings and functionalisation capacity, enabling a high-efficacy drug administration route and controlled pattern of drugs’ in vivo behaviours. This research encompasses the preparation of MOFs and their relevant drug delivery for different diseases treatment in biomedical field, which are classified according to four types of diseases including cancer, Alzheimer’s disease, pulmonary diseases, and ocular diseases. A diverse of different MOFs have been designed to treat given their corresponding properties for these diseases. Experimental outcomes from each research are also analysed to evaluate the therapeutic effectiveness and biological applicability of proposed MOFs, which is expected to provide a new idea for efficient drug delivery in disease treatment.

Extraction and preparation of metal organic frameworks from secondary aluminum ash for removal mechanism study of fluoride in wastewater

AlFuMoF was obtained by purifying the secondary aluminum ash and using hydrothermal method and modification treatment. Next, using the β-Cyclodextrin impregnation treatment AlFuMoF, a modified MOF (β-CD@AlFuMoF) was obtained. Both MOFs were subsequently characterized, and their potential for adsorption of fluoride from wastewater was compared. The characterization was performed by SEM, EDS, FTIR, XRD, particle size change and thermogravimetric. The adsorption characteristics of AlFuMoF and β-CD@AlFuMoF under different conditions of pH, contact time as well as initial concentration were evaluated using kinetic and thermodynamic studies and adsorption isotherms. In terms of dynamics, the pseudo second order model fits the experimental data best. According to the Langmuir model, the maximum fluoride adsorption capacity of AlFuMoF and β-CD@AlFuMoF are 22.56 and 39.95 mg g−1, respectively. Thermodynamic studies show that the adsorption of fluoride on AlFuMoF and β-CD@AlFuMoF are spontaneous and mainly controlled by chemical adsorption. According to the findings, β-CD modification of AlFuMoF can be considered as a promising method for removing fluoride from wastewater.

Recent Advances in Metal‐Organic‐Framework‐Based Composites for Efficient Sequestration of Organophosphorus Pesticides (OPPs)

AbstractThe uncontrolled utilization of organophosphate pesticides (OPPs) has resulted in substantial environmental issues globally, that pose significant threat to human health. As a result, effective sequestration of these OPPs has taken into consideration by several researchers and environmental scientists. In this context, metal‐organic frameworks (MOFs) have attracted a lot of attention in the field of adsorption due to their superabundant attachment sites, easy functionalization process, strong stability, tunable pore size, and rich topology. Therefore, the present review critically summarizes MOF based adsorbents such as pristine, functionalized, composites, and MOF‐derived materials along with the choice of precise linkers for the preparation of MOFs. Functionalizing agent used to achieve maximum adsorption by MOF is extensively explored. Possible mechanism, major interaction pathway for the mitigation of OPPs has also been focused. Finally, development of effective MOFs for successful implementation is recommended, along with future prospects for large‐scale applications.

Preparation of metal organic frameworks modified chitosan composite with high capacity for Hg(II) adsorption

In this study, a novel modified chitosan composite adsorbent (UNCS) was prepared by crosslinking between chitosan and metal organic frameworks (MOFs) material UiO-66-NH2 using epichlorohydrin as crosslinker. The influence of the prepared conditions was investigated. The structure and morphology of the composite were characterized by FT-IR, XRD, SEM, TGA, BET and zeta potential analysis. Effects of different variables for adsorption of Hg(II) on this adsorbent were explored. The kinetic studies indicated that the adsorption process followed the pseudo-second-order kinetic model and the adsorption equilibrium could be reached within 2 h. The adsorption was mainly controlled by chemical process. Adsorption isothermal studies illustrated that the adsorption fitted Langmuir isotherm model, implying the homogeneous adsorption on the surface of the adsorbent. The adsorbent exhibited high uptake and the maximum capacity from Langmuir model could reach 896.8 mg g−1 at pH 6. Thermodynamic studies showed the spontaneous nature and exothermic nature of the adsorption process. Additionally, the removal of Hg(II) on UNCS could achieve over 90 %. The adsorption-desorption cycled experiments indicated the appropriate reusability of the adsorbent. Hence, this adsorbent would be promising for the removal of Hg(II) from wastewater.

Fe-Trimesic Acid/Melamine Gel-Derived Fe/N-Doped Carbon Nanotubes as Catalyst of Peroxymonosulfate to Remove Sulfamethazine

The conventional precursor preparation of metal–organic frameworks (MOFs) for nitrogen-doping carbon materials is divided into the preparation of MOFs and the mixing of the nitrogen source, which is a complex and time-consuming step. In this study, Fe-BTC gel/nitrogen source-derived carbon materials were synthesized using one or more of the following raw ingredients: Fe(NO3)3·9H2O, FeCl3·6H2O, Fe2(SO4)3, trimesic acid, melamine and dicyandiamide. The influence of different raw ingredients on the preparation and performance of catalysts was investigated. Fe(NO3)3·9H2O can react with trimesic acid to form a gel with ethanol as solvent, and the gel helped the homogeneous dispersion of the added melamine and did not precipitate. Fe-C-N(M), synthesized from the three materials mentioned, was identified as the optimal catalyst; the removal rate of 5 mg/L sulfadimethoxine (SMZ) reached 100% at 15 min when the Fe-C-N(M) dosage was 50 mg/L, PMS concentration was 0.5 mM, and the pH was 5.78 (initial pH of the solution). The removal of SMZ was not significantly inhibited by the pH (3–9) and 0–10 mM inorganic anions (Cl−, NO3−, HCO3− and H2PO42−). Through quenching tests, electron paramagnetic resonance and probe experiments, 1O2 and a small amount of free radicals (•OH and SO4•−) bound on the catalyst surface are discovered to be the primary active ingredients that activate PMS to degrade SMZ.

Development of MOF Based Recyclable Photocatalyst for the Removal of Different Organic Dye Pollutants

The preparation of metal organic frameworks (MOFs) has come to the forefront in recent years because of their outstanding physical and chemical properties. Many MOFs such as Zn, Co, Ni, Fe, and Ag, etc., have been successfully synthesized. In this work, we followed the solvothermal assisted route to synthesize Ag-MOF (abbreviated as AMOF) nanosheets and then applied them as a photocatalyst to remove different organic pollutants, namely methyl orange (MO), crystal violet (CV), and methylene blue (MB). Chemical composition, optical properties, morphology, and microstructural analysis were analyzed using XPS, UV-visible spectrophotometer, FESEM, TEM, and EDS, respectively. The structural properties of AMOF nanosheets were studied by X-ray diffraction (XRD). Nitrogen adsorption and desorption isotherm analysis were utilized to evaluate the specific surface area and pore size of the AMOF nanosheets. Further, AMOF nanosheets showed notable photocatalytic performance for various dye pollutants degradation. The results confirmed 74.5, 85.5, and 90.7% of MO, CV, and MB dye pollutants removal after 120 min of irradiation with the rate constants (k) of 0.0123, 0.0153, and 0.0158 min-1, respectively. The effect of superoxide radicals (O2-) and photogenerated holes (h+) on the organic dye pollutants removal was investigated using radical scavenger trapping studies. Moreover, the stability study also confirmed the recyclability of the photocatalyst. Therefore, the findings of this research present a realizable method to grow AMOF photocatalyst for successful degradation of various dye pollutants.

Synthesis of FeCoNi/C decorated graphene composites derived from trimetallic metal-organic framework as ultrathin and high-performance electromagnetic wave absorbers.

High-temperature pyrolysis of metal-organic framework (MOF) is an effective way to prepare lightweight and high-performance electromagnetic wave absorbers. In this work, iron cobalt nickel/carbon (FeCoNi/C) decorated graphene composites were fabricated by the two-step method of solvothermal reaction and pyrolysis treatment. Results of micromorphology analysis demonstrated that numerous octahedral FeCoNi/C carbon frameworks were almost uniformly distributed on the wrinkled surfaces of flaky graphene. Moreover, the electromagnetic parameters and wave absorbing properties of obtained composites were regulated through simply changing the addition amounts of graphene oxide. Significantly, the as-prepared FeCoNi/C decorated graphene composite with the addition amount of graphene oxide of 67.2mg exhibited the best electromagnetic absorption performance. The minimum reflection loss was as large as -66dB at 15.6GHz and broad absorption bandwidth reached up to 4.8GHz with an ultrathin thickness of 1.53mm and a filler loading ratio of 30wt%. Furthermore, the maximum absorption bandwidth was enlarged to 5.2GHz via slightly adjusting the matching thickness to 1.56mm. Additionally, the probable electromagnetic attenuation mechanisms of attained composites were proposed. The results of this study would provide a reference for the preparation of MOF derived carbon-based magnetic composites as ultrathin and high-performance electromagnetic absorbers.

Preparation of metal-organic framework from in situ self-sacrificial stainless-steel matrix for efficient water oxidation

The oxygen evolution reaction (OER) on the anode is one of the key half-cell reactions in water electrolysis and metal-air batteries, and its reaction process is mainly hampered by sluggish kinetics and low efficiency. In this work, a series of MIL-53 metal-organic framework (MOF) derived materials grown on self-sacrificial SSM substrate was designed and synthesized for efficient water oxidation in alkaline solutions. The as-obtained FeNiBDC/SSM (SSM = stainless steel matrix and H2BDC = benzene-1,4-dicarboxylic acid) with MIL-53 MOF of uniform morphology and high porosity was successfully synthesized via a facile one-step method using recycled stainless steel as a template. Afterward, FeNiBDC/SSM was accompanied by morphological and structural changes during the OER process while the modified MOF components on the SSM substrate degraded into Fe/NiOOH species, which serve as catalytic centers. After the stability test for 100 h, the used optimal FeNiBDC/SSM2 exhibited a promising electrocatalytic OER performance with a low Tafel slope of 74.5 mV dec-1, a small overpotential of 239 mV at 10 mA cm-2, and high current retention of 95.20 %. This work provides a new research idea for the sustainable recycling of existing resources and the one-step in-situ preparation of MOF/substrate electrocatalyst for OER.

Metal-organic Frameworks for Natural Gas Storage

Methane, as the transitional fuel, still emits CO2 during combustion but less than gasoline. Developing new adsorption materials can improve the efficiency of methane storage and then achieve the goal safely and economically. Metal-organic Frameworks (MOF) with the advantage of high porosity and adjustable pore surface area, are considered one of the promising materials for natural storage. Here, this article briefly introduces the preparation of MOF and mentions some details during this process such as the solvothermal technique, and electrochemical synthesis methods, covering some defects in the preparation process. Many kinds of materials have different volumetric adsorption rates and mass adsorption rates compared with DOE standards. In chronological order, this paper lists some typical materials and discusses specific structures inside MOFs corresponding to relative performance. Changing or adjusting organic ligands can improve capacities so that a series of MOFs are designed like MFM-132, MFM-112 and MFM-115. In addition, the factors influencing adsorption rate are also considered including internal factors, surface area, porosity, structure, adsorption isotherm and external factors, pressure, and temperature, respectively

Enhanced catalytic activity of MOF-74 via providing additional open metal sites for cyanosilylation of aldehydes

The preparation of metal-organic frameworks (MOFs) having many open metal sites is an excellent approach for the development of highly active MOF-based catalysts. Herein, well-defined rice-shaped MOF-74 microparticles having structural defects are prepared by incorporating two analogous organic linkers [2,5-dihydroxy-1,4-bezenedicarboxylic acid (DHBDC) and 2-hydroxy-1,4-benzenedicarboxylic acid (HBDC)] within the MOF-74 structure. The replacement of some of DHBDC in MOF-74 by HBDC causes the structural defects (excluding some of the bridged hydroxyl groups), and these structural defects provide the additional open metal sites within MOF-74. Finally, the additional open metal sites within MOF-74 result in the enhanced catalytic activity for the cyanosilylation of several aldehydes. A series of MOF-74s is prepared with various incorporated amounts of HBDC, and the optimum ratio between DHBDC and HBDC in MOF-74 to achieving the best catalytic performance is determined. In addition, the defected MOF-74 displays an excellent recyclability for the catalytic reaction.