In this study, the potential of microporous 3D metal–organic framework (MOF) for curing epoxy resin has been discussed. First, MIL-101 (Cr), a chromium based MOF, was synthesized under hydrothermal ...condition and then characterized by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric (TGA) measurements. Epoxy nanocomposites containing 0.1, 0.3 and 0.5 wt% of MOF nanocrystals were subsequently prepared and their curability was studied in terms of the universal dimensionless Cure Index (CI) criterion under nonisothermal differential scanning calorimetry (DSC). Based on calculations made on the basis of the CI, epoxy nanocomposites containing 0.1, 0.3, and 0.5 wt% of MOF were labeled Good and Excellent thanks to an enhanced chemical interaction between MOF and epoxy matrix, where the heat of cure in the system was surprisingly even higher than that of the neat epoxy. It was demonstrated that introduction of MOF into epoxy significantly improved the heat release during crosslinking process of epoxy, as indicated by a 63% rise in the enthalpy of cure at MOF loading of 0.1 wt%. Addition of thermally stable MOF nanomaterials to the epoxy resin improved thermal decomposition resistance of epoxy. Up to 0.3 wt% loading, the system revealed acceptable thermal stability at elevated temperature featured by more residue remained at the end of test, while sample containing 0.5 wt% MOF resisted against decomposition at early stages of degradation due to higher thermal stability of MOF with respect to epoxy resin.
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•Synthesized 3D metal–organic framework (MOF) structures and fully characterized them.•Prepared epoxy/MOF nanocomposites at different loading levels and cured nonisothermally.•Studied cure potential of nanocomposites by nonisothermal DSC varying heating rate.•Cure Index demonstrated Good and Excellent cured epoxy/MOF at high heating rates.
A key challenge in trace heavy metals removal from drinking water by adsorption technology is to achieve high adsorption capacity and rapid uptake speed of adsorbent. Herein, we report a ...functionalized double modified covalent organic framework (DMTD–COF–SH) bearing high-density sulfur and nitrogen chelating groups provided simultaneously by 2,5-dimercapto-1,3,4-thiadiazole (DMTD) and 1,2-ethanedithiol, which was prepared via a facile one-pot thiol-ene “click” reaction. PXRD, FTIR, XPS, SEM, BET and 13C MAS NMR confirmed their successful graft, and DMTD was found to be more easily grafted on the COF surface layer than 1,2-ethanedithiol. The as-prepared DMTD–COF–SH showed remarkable adsorption capacity and ultrafast uptake dynamics to trace heavy metals owing to the synergistic effects resulting from densely populated sulfur and nitrogen chelating groups within ordered COF mesopores and at the COF surface. On the basis of the drinking water treatment units standard NSF/ANSI 53–2020, when the adsorbent dosage was 10 mg/30 mL and 20 mg L−1 calcium ions coexisted, the lead concentration decreased from initial 150 μg L−1 to 2.89 μg L−1 within 10 s, far below the allowable limit of world health organization (WHO) drinking water standard (10 μg L−1), and the maximum adsorption capacity meeting the standard attained 14.22 mg g−1. The adsorbent also exhibited excellent stability, wide applicable pH range and outstanding adsorption performance for coexisting trace lead, mercury, cadmium, chromium (VI) and copper in tap water, indicating that the DMTD–COF–SH material has excellent application prospect for trace heavy metals removal from drinking water.
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•COF–V was successfully double modified by DMTD and ethanedithiol via a facile method.•DMTD–COF–SH contains high-density S and N chelating groups with strong affinity.•DMTD–COF–SH shows ultrafast uptake speed, large uptake capacity and good stability.•DMTD–COF–SH shows good removal performance for multiple coexisting trace heavy metals.•DMTD–COF–SH shows wide applicable pH range and excellent application prospect.
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•The advance of post-synthetic modification (PSM) of MOFs in the past five years was reviewed.•Two increasingly apparent tendencies in PSM of exploring new types and tandem reactions ...were demonstrated.•Selected examples including several from China focus on new types and tandem PSM.
In the past five years, post-synthetic modification (PSM) has become a very useful strategy in systematically functionalizing metal–organic frameworks (MOFs) by modifying the linker, metal node, pore character, and surface environment for the purpose of increasing the structural stability and introducing desired properties. In this review, we intend to demonstrate the two major trends in PSM including the mushrooming of new types of reaction and the combination of multi-steps PSM. The selected examples illustrate three promising PSM classes, post-synthetic metal exchange (PSME), post-synthetic ligand exchange (PSLE) and post-synthetic elimination and insertion (PSE&I). Combined with the well-developed covalent PSM and dative PSM, tandem PSM which constitutes of multistep and different types of reaction adds to the step-by-step improvement of catalytic activity, regulating magnetism and others. These recent advances in PSM not only open new paths to improve the function of MOFs, but also reveal the unprecedented reaction complexity of crystalline solids.
Engineering of controlled hybrid nanocomposites creates one of the most exciting applications in the fields of energy materials and environmental science. The rational design and in situ synthesis of ...hierarchical porous nanocomposite sheets of nitrogen‐doped graphene oxide (NGO) and nickel sulfide (Ni7S6) derived from a hybrid of a well‐known nickel‐based metal‐organic framework (NiMOF‐74) using thiourea as a sulfur source are reported here. The nanoporous NGO/MOF composite is prepared through a solvothermal process in which Ni(II) metal centers of the MOF structure are chelated with nitrogen and oxygen functional groups of NGO. NGO/Ni7S6 exhibits bifunctional activity, capable of catalyzing both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with excellent stability in alkaline electrolytes, due to its high surface area, high pore volume, and tailored reaction interface enabling the availability of active nickel sites, mass transport, and gas release. Depending on the nitrogen doping level, the properties of graphene oxide can be tuned toward, e.g., enhanced stability of the composite compared to commonly used RuO2 under OER conditions. Hence, this work opens the door for the development of effective OER/HER electrocatalysts based on hierarchical porous graphene oxide composites with metal chalcogenides, which may replace expensive commercial catalysts such as RuO2 and IrO2.
A rational and simple methodology to fabricate hierarchical porous nanocomposite sheets of nitrogen‐doped graphene oxide and nickel sulfide derived from a metal‐organic framework is presented. The resulting composite shows bifunctional activity of hydrogen evolution reaction and oxygen evolution reaction with excellent stability in alkaline electrolytes.
Predictive analytic models leveraging machine learning methods increasingly have become vital to health care organizations hoping to improve clinical outcomes and the efficiency of care delivery for ...all patients. Unfortunately, predictive models could harm populations that have experienced interpersonal, institutional, and structural biases. Models learn from historically collected data that could be biased. In addition, bias impacts a model’s development, application, and interpretation. We present a strategy to evaluate for and mitigate biases in machine learning models that potentially could create harm. We recommend analyzing for disparities between less and more socially advantaged populations across model performance metrics (eg, accuracy, positive predictive value), patient outcomes, and resource allocation and then identify root causes of the disparities (eg, biased data, interpretation) and brainstorm solutions to address the disparities. This strategy follows the lifecycle of machine learning models in health care, namely, identifying the clinical problem, model design, data collection, model training, model validation, model deployment, and monitoring after deployment. To illustrate this approach, we use a hypothetical case of a health system developing and deploying a machine learning model to predict the risk of mortality in 6 months for patients admitted to the hospital to target a hospital’s delivery of palliative care services to those with the highest mortality risk. The core ethical concepts of equity and transparency guide our proposed framework to help ensure the safe and effective use of predictive algorithms in health care to help everyone achieve their best possible health.
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•The application of MOF-based materials for antibacterials removal is first reviewed.•The adsorption/desorption performances and mechanisms were analyzed and discussed.•Effective ...strategies for boosting adsorption and future research directions were suggested.
The request of advanced adsorbents for antibacterials removal from pharmaceutical wastewater has recently been more and more urgent. Metal-organic frameworks (MOFs) have been proved as promising adsorbents in terms of excellent porosity, designable adsorption sites, and controllable water stability. This review details the works that have been reported on water-phase adsorption of antibacterials using MOF-based adsorbents. The adsorption behaviors of antibacterials in the materials and corresponding structure-performance relationships were discussed. Further, based on the various adsorption mechanisms, we concluded several feasible strategies for boosting adsorption performances of MOFs from the standpoints of both surface adsorption and pore adsorption. At last, we suggested the current challenges of antibacterials adsorption in MOFs and proposed our insights for future researches. We hope this review will promote the fast development of MOFs in the field of antibacterial removal.
Metal‐organic frameworks (MOFs) have experienced a tremendous growth during last few decades as porous crystalline molecular materials. The comprehensive effect of structural diversity, tunability ...and high surface area makes MOFs suitable for multifarious applications. MOFs can act as potential receptors toward different target components along with ionic species, small molecules, solvents, explosives etc. Anion recognition remains an important phenomena due to its involvement in many chemical and biological processes. Ligand designing, incorporation of appropriate functional groups and post‐synthetic modifications are key strategies in MOFs for selective recognition and scavenging of environmentally toxic and detrimental anions (i. e. cyanide, oxo‐anions etc.). The main focus of this personal account is on our research towards development and potential applications of MOFs with special emphasis on selective and sensitive anion sensing.
Metal‐organic frameworks (MOFs) have experienced a tremendous growth during last few decades as porous crystalline molecular materials. The comprehensive effect of structural diversity, tunability and high surface area makes MOFs suitable for multifarious applications. MOFs can act as potential receptors toward various target components including ionic species, small molecules, solvents, explosives etc. Anion recognition remains important phenomena considering many chemical and biological processes. Ligand designing, incorporation of appropriate function groups and post‐synthetic modifications are key strategies in MOFs for selective recognition and scavenging of environmentally toxic and detrimental anions (i. e. cyanide, oxo‐anions etc.). The main focus of this personal account is on our research towards development and potential applications of MOFs with special emphasis on selective and sensitive anion sensing.
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This work reports the effect of using dimethylformamide (DMF) as the solvent for synthesizing MIL-53(Al). This well-known breathing MOF is typically prepared using hydrothermal ...methods. The two materials synthesized in DMF at 120°C and 220°C show significant deviations from the breathing behavior exhibited by the material synthesized hydrothermally. Powder X-ray diffraction confirmed that MIL-53(Al) synthesized in DMF at 120°C remains in the large-pore form under all conditions, while the other material synthesized at 220°C undergoes a more gradual breathing transition than is observed for MIL-53(Al) prepared by traditional methods. Solid-state NMR was employed to elucidate additional structural information and gain insight into the role synthesis solvent plays on breathing behavior. The CO2 and water adsorption of these large-pore stabilized materials were studied, and the differences in adsorption behavior compared to MIL-53(Al) prepared by traditional methods was discussed.
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•The CoP-NC@NFP electrocatalyst is well prepared and characterized.•CoP-NC@NFP exhibited excellent electrochemical activity as well as good stability in overall water ...splitting.•CoP-NC@NFP have retained their structural property after stability.•CoP-NC@NFP offers excellent performance and good stability (over 200 h) in zinc-air battery.
Highly active, long-lasting, and low-cost nanostructured catalysts with efficient oxygen evolution and oxygen reduction reactions (OER and ORR) are critical for achieving high-performance zinc-air batteries. Herein, we developed CoP-nitrogen-doped carbon@NiFeP nanoflakes (CoP-NC@NFP), derived from MOF enriched with multiple active sites, for multifunctional water splitting and zinc-air battery applications. The experimental results revealed that the multiple active catalytic sites of CoP-NC@NFP were responsible for the excellent charge-transfer kinetics and electrocatalytic performance with respect to water splitting. This performance is comparable to that of precious metal catalysts in alkaline electrolytes (OER: overpotential of 270 mV; HER: overpotential of 162 mV; ORR: Tafel slope of 46 mV dec−1; overall water splitting device: cell voltage of 1.57 V at 10 mA cm−2) with excellent electrochemical durability. Additionally, the structural stability of the OER and the HER durability of the CoP-NC@NFP electrocatalyst were confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) studies. Most impressively, zinc-air batteries (ZABs) assembled with CoP-NC@NFP as the air–cathode exhibit exceptionally high power density of 93 mW cm−2 and prolonged operational stability over 200 h compared with a ZAB equipped with a benchmark air–cathode. The outcome of this study opens a practical possibility for the preparation of efficient multifunctional catalysts free of noble metals for clean energy production and storage.
In this work, electro-enhanced solid-phase microextraction (EE-SPME) and covalent organic framework (COF) were adopted to improve the extraction efficiency. A conductive COF synthesized of ...2,6-diaminoanthraquinone (DQ) and 1,3,5-triformylphloroglucinol (TP) was in situ bonded to the stainless steel wire via facile solution-phase approach and used as the EE-SPME fiber coating to preconcentrate a typical endocrine disruptor bisphenol A (BPA). Compared with conventional SPME, the DQTP bonded fiber coupled with EE-SPME device exhibited higher extraction efficiency and achieved extraction equilibrium within 10 min. The proposed approach based on EE-SPME and gas chromatography coupled with flame ionization detector gave a linear range of 0.05–10 μg mL−1 and detection limit of 3 μg L−1 (S/N = 3) with good precision (<6.7%) and reproducibility (<7.1%) spiked with 0.1, 0.5, 1.0 μg mL−1 BPA. Quantitative determination of BPA in extracts of food packagings (mineral water bottles, milk boxes and milk tea cups) was achieved with recoveries from 88.6 to 118.0%.
A sampling device based on a conductive covalent organic framework (COF, DQTP) and electro-enhanced solid-phase microextraction has been constructed for rapid extraction of bisphenol A. Display omitted
•Covalent organic framework DQTP was grown in situ on stainless steel wire via Schiff base reaction.•Extraction efficiency of SPME was enhanced by the external electrical field with shorter extraction time.•The developed EE-SPME coupled with GC-FID method was applied to determine bisphenol A in extracts of food packagings.
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