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1.
    
The design, synthesis, and structural characterization of two new microporous metal‐organic framework (MMOF) structures is reported; Zn(BDC)(DMBPY)0.5·(DMF)0.5(H2O)0.5 (1; H2 BDC = 1,4‐benzenedicarboxylic acid; DMBPY=2,2′‐dimethyl‐4,4′‐bipyridine) and Zn(NDC)(DMBPY)0.5·(DMF)2 (2; H2NDC = 2,6‐naphthalenedicarboxylic acid, DMF=N,N,‐dimethylformamide), which are obtained by functionalizing a pillar ligand with methyl groups. Both compounds are 3D porous structures of the Zn2(L)2(P) type and are made of a paddle‐wheel Zn2(COO)4 secondary building unit (SBU), with the dicarboxylate and DMBPY as linker (L) and pillar (P) ligands, respectively. Comparisons are made to the parent structures Zn(BDC)(BPY)0.5·(DMF)0.5(H2O)0.5 (3; BPY = 4,4′‐bipyridine) and Zn(NDC)(BPY)0.5·(DMF)1.575 (4) to analyze and understand the effect of methyl functionalization. CO2‐adsorption studies indicate substantially enhanced isosteric heats of CO2 adsorption (Qst) for both compounds, as a result of adding methyl groups to the BPY ligand. The CO2 uptake capacity, however, is affected by two opposing and competing factors: the enhancement due to increased MMOF–CO2 interactions (higher Qst values) and detraction due to the surface area and pore‐volume reduction. For 1′ (the guest‐free form of 1), the positive effect dominates, which leads to a significantly higher uptake of CO2 than that of its parent structure 3′ (the guest‐free form of 3). In 2′ (the guest‐free form of 2), however, the negative effect rules, which results in a slightly lower CO2 uptake with respect to 4′ (the guest‐free form of 4). All four compounds exhibit a relatively high separation capability for carbon dioxide over other small gases, including CH4, N2, and O2. The separation ratios of CO2 to O2 and N2 (at 298 K and 1 atm) are 39.8 and 23.5 for compound 1′, 57.7 and 40.2 for 2′, 25.7 and 29.5 for 3′, 89.7, and 20.3 for 4′, respectively. IR and Raman spectroscopic characterization of CO2 interactions with 1′ and 2′ provides indirect support of the importance of the methyl groups in the interaction of CO2 within these systems.  相似文献   

2.
    
A new type of photodynamic carbon capture material with up to 26 wt% CO2 desorption capacity is synthesized via incorporation of diarylethene (DArE) as guest molecules in porous aromatic framework‐1 (PAF‐1). In these host–guest complexes, the carboxylic acid groups featured in DArE allow multiple noncovalent interactions to exist. DArE loadings ranging from 1 to 50 wt% are incorporated in PAF‐1 and the complexes characterized by UV–vis spectroscopy, FT‐IR spectroscopy, CO2, and N2 adsorption. Successful inclusion of DArE in PAF‐1 is indicated by the reduction of pore size distributions and an optimum loading of 5 wt% is determined by comparing the percentage photo­response and CO2 uptake capacity at 1 bar. Mechanistic studies suggest that photoswitching modulates the binding affinity between DArE and CO2 toward the host, triggering carbon capture and release. This is the first known example of photodynamic carbon capture and release in a PAF.  相似文献   

3.
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4.
    
The moisture‐tolerant metal‐organic frameworks (MOFs) of formula [Zn4O(L)3]n (L = di‐substituted carboxypyrazolate derivatives) are fabricated as thin films on self‐assembled monolayer (SAM) functionalized gold substrates by employing the step‐by‐step liquid phase epitaxial (LPE) deposition method in a continuous operation mode. The in situ monitoring of the deposition by quartz crystal microbalance (QCM) and grazing incidence X‐ray diffraction reveal different growth regimes and crystallinities of the obtained thin films in dependence of the chosen alkyl side chain functionality at the carboxypyrazolate linkers, L. To overcome the relatively poor crystallinity and low porosity of a particular homostructured metal‐organic framework type B film, the step‐by‐step heteroepitaxial growth of this MOF B on top of the crystallite surfaces of a well‐grown and lattice‐matched MOF type A is applied. This approach enables the fabrication of oriented, core‐shell‐like MOF B @ A surface mounted heterocrystals as an intergrown homogeneous coating for the selective adsorption of volatile organic compounds. The accessible pore volumes of the individual components and the heterostructured films are characterized by performing adsorption measurements of different organic probe molecules using an environmentally controlled QCM instrument. The results show good adsorption capacity, excellent size exclusion selectivity for alcohols, and a high degree of moisture‐tolerance of the heteroepitaxial MOF films.  相似文献   

5.
    
3D metal carbide@mesoporous carbon hybrid architecture (Ti3C2Tx@Meso‐C, TX ≈ FxOy) is synthesised and applied as cathode material hosts for lithium‐sulfur batteries. Exfoliated‐metal carbide (Ti3C2Tx) nanosheets have high electronic conductivity and contain rich functional groups for effective trapping of polysulfides. Mesoporous carbon with a robust porous structure provides sufficient spaces for loading sulfur and effectively cushion the volumetric expansion of sulfur cathodes. Theoretical calculations have confirmed that metal carbide can absorb sulfur and polysulfides, therefore extending the cycling performance. The Ti3C2Tx@Meso‐C/S cathodes have achieved a high capacity of 1225.8 mAh g?1 and more than 300 cycles at the C/2 current rate. The Ti3C2Tx@Meso‐C hybrid architecture is a promising cathode host material for lithium‐sulfur batteries.  相似文献   

6.
    
Herein, a post-synthetic modification strategy is used to covalently graft polyamines, including ethylenediamine (ED), diethylenetriamine (DETA), tris(2-aminoethyl)amine (TAEA), and polyethyleneimine (PEI) to the amino-ligand inside of a Cr-MOF, NH2-Cr-BDC, for post-combustion carbon capture applications. X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and ion chromatography (IC) reveal that ≈45% of the MOF ligands are grafted with polyamines. Next, assessment of CO2 uptake, CO2/N2 selectivity, isosteric heats of CO2 adsorption, separation performance during humid CO2/N2 (15/85) breakthrough experiments, and cyclability, reveals an enhanced performance for the polyamine-containing composites and the following performance trend: NH2-Cr-BDC<ED<DETA<TAEA<PEI. The best-performing materials, including the TAEA and PEI-grafted MOFs, offer CO2 uptakes of 1.0 and 1.55 mmol g−1, respectively, at 0.15 bar and 313 K. Further, these composites also offer a high CO2 capacity after 200 temperature swing adsorption/desorption (TSA) cycles in simulated humid flue gas. Last, after soaking the composites in water, there is no loss of CO2 capacity; on the contrary, when the same MOF is impregnated with polyamines using traditional approaches, there is ≈85% CO2 capacity loss after soaking. Thus, this covalent grafting strategy successfully immobilizes amines in MOF pores preventing leaching and hence can be an effective strategy to extend the adsorbent lifetime.  相似文献   

7.
    
The vast chemical and structural tunability of metal–organic frameworks (MOFs) are beginning to be harnessed as functional supports for catalytic nanoparticles spanning a range of applications. However, a lack of straightforward methods for producing nanoparticle-encapsulated MOFs as efficient heterogeneous catalysts limits their usage. Herein, a mixed-metal MOF, NiMg-MOF-74, is utilized as a template to disperse small Ni nanoclusters throughout the parent MOF. By exploiting the difference in Ni O and Mg O coordination bond strength, Ni2+ is selectively reduced to form highly dispersed Ni nanoclusters constrained by the parent MOF pore diameter, while Mg2+ remains coordinated in the framework. By varying the ratio of Ni to Mg in the parent MOF, accessible surface area and crystallinity can be tuned upon thermal treatment, influencing CO2 adsorption capacity and hydrogenation selectivity. The resulting Ni nanoclusters prove to be an active catalyst for CO2 methanation and are examined using extended X-ray absorption fine structure and X-ray photoelectron spectroscopy. By preserving a segment of the Mg2+-containing MOF framework, the composite system retains a portion of its CO2 adsorption capacity while continuing to deliver catalytic activity. The approach is thus critical for designing materials that can bridge the gap between carbon capture and CO2 utilization.  相似文献   

8.
    
Mixed‐matrix membranes comprising NH2‐MIL‐53(Al) and Matrimid or 6FDA‐DAM have been investigated. The metal organic framework (MOF) loading has been varied between 5 and 20 wt%, while NH2‐MIL‐53(Al) with three different morphologies, nanoparticles, nanorods, and microneedles has been dispersed in Matrimid. The synthesized membranes have been tested in the separation of CO2 from CH4 in an equimolar mixture. At 3 bar and 298 K for 8 wt% MOF loading, incorporation of NH2‐MIL‐53(Al) nanoparticles leads to the largest improvement compared to nanorods and microneedles. The incorporation of the best performing filler, i.e., NH2‐MIL‐53(Al) nanoparticles, into the highly permeable 6FDA‐DAM has a larger effect, and the CO2 permeability increases up to 85% with slightly lower selectivities for 20 wt% MOF loading. Specifically, these membranes have a permeability of 660 Barrer with a CO2/CH4 separation factor of 28, leading to a performance very close to the Robeson limit of 2008. Furthermore, a new non‐destructive technique based on Raman spectroscopy mapping is introduced to assess the homogeneity of the filler dispersion in the polymer matrix. The MOF contribution can be calculated by modeling the spectra. The determined homogeneity of the MOF filler distribution in the polymer is confirmed by focused ion beam scanning electron microscopy analysis.  相似文献   

9.
    
Herein, novel carbons that, owing to a high density of micropores (up to 79%) and N-content (up to 14.9%), offering exciting potential for post-combustion CO2 capture are reported. Given that little is known about how starting materials impact the structure and performance of carbons, three different microporous materials are pyrolyzed. These include a Co-(metal-organic framework) (MOF), a Co-MOF-polymer composite, and a coordination polymer derived from the same monomer and cobalt ions. Notably, the cobalt, which is required to drive the polymerization, is subsequently leached from the carbons via acid for its reuse in MOF synthesis. Next, various metrics including CO2 capacity, selectivity, isosteric heat of adsorption, breakthrough time and cyclability are assessed. The acid treated carbons adsorb 0.21, 0.99, and 1.11 mmol CO2 g−1, respectively, (313 K, 0.15 bar) with CO2/N2 selectivity ranging from 37 to 52. Due to superior capacity, the polymer-derived carbons also reveal impressive breakthrough times in simulated flue gas mixtures (15% CO2/85% N2, 80% RH, 313 K) ranging from 33 to 40 min g−1. Similar performance is also observed under dry conditions and after pre-saturation with water for 1.5 h. Remarkably, no loss in working capacity is observed after 100 CO2 TSA cycles (313 K/393 K).  相似文献   

10.
    
Crystalline porous materials (CPMs), including covalent organic frameworks (COFs) and metal–organic frameworks (MOFs), are promising materials for advanced separation technologies. However, the challenge of transforming nanoscale CPMs into large-area functional membranes hinders their application in the membrane separation process. Herein, a self-standing pure COF (TpPa-1) nanofiber membrane with high crystallinity, good flexibility, excellent mechanical properties, and scalability is prepared using an electrospinning process and polymer sacrificial template strategy. Subsequently, the COF nanofiber membrane is innovatively used to replace traditional inorganic discs, metal meshes, and polymer membranes as porous supports, and the COF–MOF composite CPM membrane is prepared through the tailorable and confined growth of zeolite imidazolium salt frame-8 (ZIF-8) on the surface of the COF membrane and in the gaps of the COF nanofibers. The COF–MOF composite membrane exhibits excellent permeability and significantly enhances separation selectivity for organic dyes. Moreover, MOF and COF form an interpenetrating network structure, and their similar chemical properties improve the interfacial stability between the two phases, giving the COF–MOF composite membrane good long-term separation performance. This is the first self-standing composite CPM membrane with excellent molecular sieving performance, which provides new insights into the design of high-performance and robust composite membranes.  相似文献   

11.
    
Homogenous radioactive gas contamination constitutes the hardest challenge for radioprotection due to its elusive nature. Most common radioactive gas are 85Kr, 222Rn, and tritiated (3H) vapors. Each of them has different challenges, often leading to specialized single-gas detectors. The state-of-the-art detection either produces chemical-radiological waste, is hard to implement online, or requires large volume. A new paradigm is presented for radioactive gas detection that can perform online detection on any gas and fit in the hand. This study use photoluminescent metal organic frameworks (MOFs) as both porous gas sponges and scintillators. The response of several zinc based MOF is studied, using a unique radioactive gas test bench. These tests showed that MOFs are able to both concentrate and detect successfully 85Kr. The investigation is completed with calibration with different activities. The study also reports detection of 222Rn, and measurement of its half-life. Finally, the study is completed with the successful detection of tritiated dihydrogen, commonly known to be a hard radionuclide to detect due to its low energy and penetration range. This paper shows that scintillating MOFs are a powerful solid-state approach and a practical solution to the challenge of radioactive gas measurements.  相似文献   

12.
    
Black phosphorus (BP) is a promising 2D nanomaterial with a great potential in various areas, while its intrinsic instability greatly suppresses practical applications, particularly under harsh conditions (e.g., high temperature). Herein, BP functionalization with Al ion is achieved in an integrated manner through MIL‐53 metal‐organic framework (MOF) coating, which greatly improves both ambient and thermal stability of BP. For the obtained MIL‐53 coated BP (BP@MIL‐53), abundant Al ion within MIL‐53 interacts with the lone pair electrons of BP, and subsequently decreases the BP surface electron density, reducing the reactivity of BP toward O2 and H2O. The MOF growth crosslinks the Al ion on the BP surface, and achieves integrated functionalization to withstand the detachment of individual Al ion from the BP surface. The noncovalent bond of BP? Al and highly porous structure of MIL‐53 preserve the physical/chemical properties of BP to the maximum, and render BP@MIL‐53 with super‐stability. This functionalization strategy extends the applications of BP based devices under high temperature conditions. As a proof of concept, BP@MIL‐53 is further utilized as a NO2 gas sensor under relatively high operating temperatures. The BP@MIL‐53 sensor exhibits fast response, outstanding selectivity, and high recovery dynamic process in contrast to bare BP sensor.  相似文献   

13.
    
Metal‐organic gels (MOGs) appear as a blooming alternative to well‐known metal‐organic frameworks (MOFs). Porosity of MOGs has a microstructural origin and not strictly crystalline like in MOFs; therefore, gelation may provide porosity to any metal‐organic system, including those with interesting properties but without a porous crystalline structure. The easy and straightforward shaping of MOGs contrasts with the need of binders for MOFs. In this contribution, a series of MOGs based on the assembly of 1D‐coordination polymer nanofibers of formula [M(DTA)]n (MII: Ni, Cu, Pd; DTA: dithiooxamidato) are reported, in which properties such as porosity, chemical inertness, mechanical robustness, and stimuli‐responsive electrical conductivity are brought together. The strength of the M? S bond confers an unusual chemical resistance, withstanding exposure to acids, alkalis, and mild oxidizing/reducing chemicals. Supercritical drying of MOGs provides ultralight metal‐organic aerogels (MOAs) with densities as low as 0.03 g cm?3 and plastic/brittle behavior depending on the nanofiber aspect ratio. Conductivity measurements reveal a semiconducting behavior (10?12 to 10?7 S cm?1 at 298 K) that can be improved by doping (10?5 S cm?1). Moreover, it must be stressed that conductivity of MOAs reversibly increases (up to 10?5 S cm?1) under the presence of acetic acid.  相似文献   

14.
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15.
    
The contemporary global crises concerning clean energy, carbon emission, and water shortage necessitate the creation of innovative materials that can tackle these pressing issues. Addressing these urgent concerns requires a deeper understanding of advanced materials and their versatile chemistry. Despite this, the advancement of material platforms to address these challenges remains formidable. In this respect, reticular chemistry offers an approach to systematically assemble molecular building blocks into crystalline frameworks, enabling precise control over their chemical composition, structure, porosity, and functionality, ultimately leading to the desired properties. Herein, the usage of metal-organic frameworks and covalent organic frameworks are examined in terms of gaseous fuel storage, carbon capture, and water harvesting, highlighting their potential for addressing critical global challenges. Representative examples are evaluated through the lens of reticular chemistry, with an emphasis on exploring the relationship between their structures and properties. Finally, an extensive overview of the rapidly expanding field is provided, along with a summary and forecast of the current challenges and prospective research directions.  相似文献   

16.
    
Metal‐organic frameworks (MOFs) are very convenient self‐templated precursors toward functional materials with tunable functionalities. Although a huge family of MOFs has been discovered, conventional MOF‐derived strategies are largely limited to the sole MOF source based on a handful of the metal elements. The limitation in structure and functionalities greatly restrains the maximum performance of MOF‐based materials for fulfilling the practical potential. This study reports a polymetallic MOF‐derived strategy for easy synthesis of metal‐oxide‐based nanohybrids with precisely tailored multicomponent active dopants. A variety of MoO2‐based nanohybrids with synergistical co‐doping of W, Cu, and P are yielded by controlled pyrolysis of tailor‐made polymetallic MOFs. The W doping induces the formation of Mox W1?x O2 solid solution with better activity. The homogeneous dispersion of Cu nanocrystallites in robust P‐doped carbon skeleton creates a conductive network for fast charge transfer. Boosting by synergistically multidoping effect, the Mo0.8W0.2O2‐Cu@P‐doped carbon nanohybrids with optimized composition exhibit exceptionally long cycle life of 2000 cycles with high capacities but very slow capacity loss (0.043% per cycle), as well as high power output for lithium storage. Remarkably, the co‐doping of heavy W and Cu elements in MoO2 with high density makes them particularly suitable for high volumetric lithium storage.  相似文献   

17.
    
Membranes offer a potentially energy-efficient and space-saving solution to reduce CO2 emissions and combat global warming. However, engineering membranes with advanced materials for high permeance and reasonable selectivity is a pressing need. In this context, a series of carbazole-based conjugated microporous polymer (CMP) membranes are fabricated with thicknesses of a few hundred nanometers through in situ electropolymerization for post-combustion carbon capture. The findings reveal that various experimental conditions, including the monomer concentration, electric potential, and cyclic voltammetry (CV) cycling number, largely impact the polymerization degree of the carbazole-based CMP, thus influencing the mode of polymer chain packing. An optimal polymerization degree leads to a larger micropore size and a higher fractional free volume (FFV), thus allowing fast CO2 transport. The study first demonstrates the feasibility of using CMPs to fabricate thin film composite (TFC) membranes for post-combustion carbon capture and confirms the high controllability of their micropores. These insights provide instructive guidance for the future advancement of CMP applications in membrane fabrication for gas separation and other fields that require precise micropore generation and design.  相似文献   

18.
    
UiO‐66, a zirconium based metal–organic framework, is incorporated with nanosized carbon nitride nanosheets via a facile electrostatic self‐assembly method. This hybrid structure exhibits a large surface area and strong CO2 capture ability due to the introduction of UiO‐66. We demonstrate that electrons from the photoexcited carbon nitride nanosheet can transfer to UiO‐66, which can substantially suppress electron–hole pair recombination in the carbon nitride nanosheet, as well as supply long‐lived electrons for the reduction of CO2 molecules that are adsorbed in UiO‐66. As a result, the UiO‐66/carbon nitride nanosheet heterogeneous photocatalyst exhibits a much higher photocatalytic activity for the CO2 conversion than that of bare carbon nitride nanosheets. We believe this self‐assembly method can be extended to other carbon nitride nanosheet loaded materials.  相似文献   

19.
    
Lithium ion battery is the predominant power source for portable electronic devices, electrical vehicles, and back‐up electricity storage units for clean and renewable energies. High‐capacity and long‐life electrode materials are essential for the next‐generation Li‐ion battery with high energy density. Here bimetal‐organic‐frameworks synthesis of Co0.4Zn0.19S@N and S codoped carbon dodecahedron is shown with rooted carbon nanotubes (Co‐Zn‐S@N‐S‐C‐CNT) for high‐performance Li‐ion battery application. Benefiting from the synergetic effect of two metal sulfide species for Li‐storage at different voltages, mesoporous dodecahedron structure, N and S codoped carbon overlayer and deep‐rooted CNTs network, the product exhibits a larger‐than‐theoretical reversible Li‐storage capacity of 941 mAh g?1 after 250 cycles at 100 mA g?1 and excellent high‐rate capability (734, 591, 505 mAh g?1 after 500 cycles at large current densities of 1, 2, and 5 A g?1 , respectively).  相似文献   

20.
    
Novel carbon materials derived from metal‐organic frameworks (MOFs) have attracted much attention, but the commonly inevitable inward contraction during the carbonization process has restricted their structural variety and applications. In this work, a novel rigid‐interface induced outward contraction approach is reported for synthesizing hollow mesoporous carbon nanocubes (HMCNCs) by using ZIF‐8 nanocubes as precursors. HMCNCs exhibit a cubic morphology with the particle sizes slightly larger than ZIF‐8 nanocubes. Due to the unique outward contraction process, uniform carbon nanocubes with a hollow cavity, an outer microporous shell, and an inner mesoporous wall are simultaneously formed with a large pore size (25 nm), high surface area (1085.7 m2 g?1), high porosity (3.77 cm3 g?1), and high nitrogen content (12.2%). When used as a cathode material for Li–SeS2 batteries, the HMCNCs deliver a stable capacity of 812.6 mA h g?1 at 0.2 A g?1 after 100 cycles and an outstanding rate capability (455.1 mA h g?1 at 5.0 A g?1). The findings may pave the way for the construction of distinctive MOF‐derived carbon materials for various applications.  相似文献   

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