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1.
A UiO-66-NCS MOF was formed by postsynthetic modification of UiO-66-NH 2. The UiO-66-NCS MOFs displays a circa 20-fold increase in activity against the chemical warfare agent simulant dimethyl-4-nitrophenyl phosphate (DMNP) compared to UiO-66-NH 2, making it the most active MOF materials using a validated high-throughput screening. The −NCS functional groups provide reactive handles for postsynthetic polymerization of the MOFs into functional materials. These MOFs can be tethered to amine-terminated polypropylene polymers (Jeffamines) through a facile room-temperature synthesis with no byproducts. The MOFs are then crosslinked into a MOF–polythiourea (MOF–PTU) composite material, maintaining the catalytic properties of the MOF and the flexibility of the polymer. This MOF–PTU hybrid material was spray-coated onto Nyco textile fibers, displaying excellent adhesion to the fiber surface. The spray-coated fibers were screened for the degradation of DMNP and showed durable catalytic reactivity. 相似文献
2.
In this study, a strategy that can result in the polyaniline (PANI) solely confined within the nanopores of a metal–organic framework (MOF) without forming obvious bulk PANI between MOF crystals is developed. A water-stable zirconium-based MOF, UiO-66-NH 2, is selected as the MOF material. The polymerization of aniline is initiated in the acidic suspension of UiO-66-NH 2 nanocrystals in the presence of excess poly(sodium 4-styrenesulfonate) (PSS). Since the pore size of UiO-66-NH 2 is too small to enable the insertion of the bulky PSS, the quick formation of pore-confined solid PANI and the slower formation of well dispersed PANI:PSS occur within the MOF crystals and in the bulk solution, respectively. By taking advantage of the resulting homogeneous PANI:PSS polymer solution, the bulk PANI:PSS can be removed from the PANI/UiO-66-NH 2 solid by successive washing the sample with fresh acidic solutions through centrifugation. As this is the first time reporting the PANI solely confined in the pores of a MOF, as a demonstration, the obtained PANI/UiO-66-NH 2 composite material is applied as the electrode material for supercapacitors. The PANI/UiO-66-NH 2 thin films exhibit a pseudocapacitive electrochemical characteristic, and their resulting electrochemical activity and charge-storage capacities are remarkably higher than those of the bulk PANI thin films. 相似文献
3.
Exploring new catalytic strategies for achieving efficient CO 2 hydrogenation under mild conditions is of great significance for environmental remediation. Herein, a composite photocatalyst Zr-based MOF encapsulated plasmonic AuPt alloy nanoparticles (AuPt@UiO-66-NH 2) was successfully constructed for the efficient photothermal catalysis of CO 2 hydrogenation. Under light irradiation at 150 °C, AuPt@UiO-66-NH 2 achieved a CO production rate of 1451 μmol g metal−1 h −1 with 91 % selectivity, which far exceeded those obtained by Au@Pt@UiO-66-NH 2 with Pt shell on Au (599 μmol g metal−1 h −1) and Au@UiO-66-NH 2 (218 μmol g metal−1 h −1). The outstanding performances of AuPt@UiO-66-NH 2 were attributed to the synergetic effect originating from the plasmonic metal Au, doped active metal Pt, and encapsulation structure of UiO-66-NH 2 shell. This work provides a new way for photothermal catalysis of CO 2 and a reference for the design of high-performance plasmonic catalysts. 相似文献
4.
We report the fabrication of macroscopically and microscopically homogeneous, crack-free metal-organic framework (MOF) UiO-66-NH 2 (UiO: Universitetet i Oslo; [Zr 6O 4(OH) 4(bdc-NH 2) 6]; bdc-NH 22−: 2-amino-1,4-benzene dicarboxylate) thin films on silicon oxide surfaces. A DMF-free, low-temperature coordination modulated (CM), layer-by-layer liquid phase epitaxy (LPE) using the controlled secondary building block approach (CSA). Efficient substrate activation was determined as a key factor to obtain dense and smooth coatings by comparing UiO-66-NH 2 thin films grown on ozone and piranha acid-activated substrates. Films of 2.60 μm thickness with a minimal surface roughness of 2 nm and a high sorption capacity of 3.53 mmol g −1 MeOH (at 25 °C) were typically obtained in an 80-cycle experiment at mild conditions (70 °C, ambient pressure). 相似文献
5.
The hydrolysis of nerve agents is of primary concern due to the severe toxicity of these agents. Using a MOF-based catalyst (UiO-66), we have previously demonstrated that the hydrolysis can occur with relatively fast half-lives of 50 minutes. However, these rates are still prohibitively slow to be efficiently utilized for some practical applications ( e.g., decontamination wipes used to clean exposed clothing/skin/vehicles). We thus turned our attention to derivatives of UiO-66 in order to probe the importance of functional groups on the hydrolysis rate. Three UiO-66 derivatives were explored; UiO-66-NO 2 and UiO-66-(OH) 2 showed little to no change in hydrolysis rate. However, UiO-66-NH 2 showed a 20 fold increase in hydrolysis rate over the parent UiO-66 MOF. Half-lives of 1 minute were observed with this MOF. In order to probe the role of the amino moiety, we turned our attention to UiO-67, UiO-67-NMe 2 and UiO-67-NH 2. In these MOFs, the amino moiety is in close proximity to the zirconium node. We observed that UiO-67-NH 2 is a faster catalyst than UiO-67 and UiO-67-NMe 2. We conclude that the role of the amino moiety is to act as a proton-transfer agent during the catalytic cycle and not to hydrogen bond or to form a phosphorane intermediate. 相似文献
6.
A novel armor-type composite of metal–organic framework (MOF)-encapsulated CoCu nanoparticles with a Fe 3O 4 core (Fe 3O 4@SiO 2-NH 2-CoCu@UiO-66) has been designed and synthesized by the half-way injection method, which successfully serves as an efficient and recyclable catalyst for the selective transfer hydrogenation. In this half-way injection approach, the pre-synthetic Fe 3O 4@SiO 2-NH 2-CoCu was injected into the UiO-66 precursor solution halfway through the MOF budding period. The formed MOF armor could play a role of providing significant additional catalytic sites besides CoCu nanoparticles, protecting CoCu nanoparticles, and improving the catalyst stability, thus facilitating the selective transfer hydrogenation of nitrobenzaldehydes into corresponding nitrobenzyl alcohols in high selectivity (99 %) and conversion (99 %) rather than nitro group reduction products. Notably, this method achieves the precise assembly of a MOF-encapsulated composite, and the ingenious combination of MOF and nanoparticles exhibits excellent catalytic performance in the selective hydrogen transfer reaction, implementing a “1+1>2” strategy in catalysis. 相似文献
7.
The photocatalytic reduction of toxic Cr(VI), to green Cr(III) by visible light, is highly required. Metal-organic frameworks have been waged more and more devotion in the field of environmental remediation. Diversification along with functionalization is still thought-provoking and crucial for the progress of metal-organic framework (MOF)-based high activity materials. Herein, a succession of UiO-66-NH 2@ZnIn 2S 4 composites with varying amount of UiO-66-NH 2 is prepared by the facile solvothermal technique. Synergetic effect for Cr(VI) reduction is assessed under the influence of visible light (λ > 420 nm). UiO-66-NH 2 octahedron is detained by ZnIn 2S 4 nanoflakes. The obvious enhancement in activity is observed which is credited to the well-suited energy band construction and close interaction between the interface of ZnIn 2S 4 and UiO-66-NH 2, which leads to effective transfer and separation of photogenerated carriers. Synergistic effect could be evidently understood from the PL and UV -spectroscopy, after molding into heterostructure of UiO-66-NH 2@ZnIn 2S 4. In addition, UiO-66-NH 2@ZnIn 2S 4 composites exhibited good stability in photocatalytic reduction. Consequently, this UiO-66-NH 2 constructed composite has high potential in the field of environmental remediation. 相似文献
8.
UiO-66 amine functionalized was synthesized by solvothermal method. Post-synthetic modification of UiO-66-NH 2 with piperazine, a known promoter to enhance the chemisorption rate of CO 2 uptake, was carried out and analyzed to understand its crystalline structure, morphology and porous structure. Results show that piperazine is an effective agent for enhancing the capacity of absorption of CO 2. This porous product exhibits an improved CO 2 uptake at pressures up to 3000 kPa via physisorption and chemisorption mechanisms. The CH 4 adsorption and desorption isotherms on UiO-66, UiO-66-NH 2 and pip-UiO-66-NH 2 at temperature of 298.15 K and pressures ranging from 0 to 5000 kPa were carried out. IAS theory for a mixture of 0.05 bar CO 2, 0.85 bar CH 4 and 0.1 bar other gas revealed a selectivity factor of 19.09 for CO 2/CH 4 from pip-UiO-66-NH 2. Results show that these materials are effective adsorbents for CO 2 and CH 4 uptakes. 相似文献
9.
Atomically precise metal nanoclusters (NCs) with unique optical properties and abundant catalytic sites are promising in photocatalysis. However, their light-induced instability and the difficulty of utilizing the photogenerated carriers for photocatalysis pose significant challenges. Here, MAg 24 (M=Ag, Pd, Pt, and Au) NCs doped with diverse single heteroatoms have been encapsulated in a metal–organic framework (MOF), UiO-66-NH 2, affording MAg 24@UiO-66-NH 2. Strikingly, compared with Ag 25@UiO-66-NH 2, the MAg 24@UiO-66-NH 2 doped with heteroatom exhibits much enhanced activity in photocatalytic hydrogen production, among which AuAg 24@UiO-66-NH 2 presents the best activity up to 3.6 mmol g −1 h −1, far superior to all other counterparts. Moreover, they display excellent photocatalytic recyclability and stability. X-ray photoelectron spectroscopy and ultrafast transient absorption spectroscopy demonstrate that MAg 24 NCs encapsulated into the MOF create a favorable charge transfer pathway, similar to a Z-scheme heterojunction, when exposed to visible light. This promotes charge separation, along with optimized Ag electronic state, which are responsible for the superior activity in photocatalytic hydrogen production. 相似文献
10.
Bi2WO6/UiO-66-NH2 photocatalysts were fabricated through solvothermal method using acetic acid as template. The photocatalytic performance of as-fabricated composites was highly improved under simulated visible light due to the addition of UiO-66-NH2. The structural and chemical properties of the composites were characterized through FTIR, XRD, XPS, SEM, BET, UV–vis DRS and PL. After 90 min of visible light irradiation, the RhB at an initial concentration of 10 mg·L?1 in the solution was degraded by 99.4% due to the addition of 10 mg of the composite. There was no significant decrease in the photocatalytic activity even after four rounds of cycles. The free radical capture experiments indicate that the photogenerated holes (h+) were the main active sites. The possible photocatalytic degradation mechanism was proposed as the specific surface area of the composite was enlarged due to the uniform distribution of UiO-66-NH2 on the surface of Bi2WO6. The electron–hole pairs recombination rate was decreased due to the photogenerated electrons (e?) on the CB of Bi2WO6 which can be rapidly transferred to the CB of UiO-66-NH2 and the photogenerated holes of UiO-66-NH2 transferred to the VB of Bi2WO6. Meanwhile, the RhB was directly oxidized to H2O and CO2 by h+ to achieve the purification effect. 相似文献
11.
A series of Zr-based UiO-n MOF materials ( n=66, 67, 68) have been studied for iodine capture. Gaseous iodine adsorption was collected kinetically from a home-made set-up allowing the continuous measurement of iodine content trapped within UiO-n compounds, with organic functionalities (−H, −CH 3, −Cl, −Br, −(OH) 2, −NO 2, −NH 2, (−NH 2) 2, −CH 2 NH 2) by in-situ UV-Vis spectroscopy. This study emphasizes the role of the amino groups attached to the aromatic rings of the ligands connecting the {Zr 6O 4(OH) 4} brick. In particular, the preferential interaction of iodine with lone-pair groups, such as amino functions, has been experimentally observed and is also based on DFT calculations. Indeed, higher iodine contents were systematically measured for amino-functionalized UiO-66 or UiO-67, compared to the pristine material (up to 1211 mg/g for UiO-67-(NH 2) 2). However, DFT calculations revealed the highest computed interaction energies for alkylamine groups (−CH 2NH 2) in UiO-67 (−128.5 kJ/mol for the octahedral cavity), and pointed out the influence of this specific functionality compared with that of an aromatic amine. The encapsulation of iodine within the pore system of UiO-n materials and their amino-derivatives has been analyzed by UV-Vis and Raman spectroscopy. We showed that a systematic conversion of molecular iodine (I 2) species into anionic I − ones, stabilized as I −⋅⋅⋅I 2 or I 3− complexes within the MOF cavities, occurs when I 2@UiO-n samples are left in ambient light. 相似文献
12.
It is highly desired to achieve controllable product selectivity in CO 2 hydrogenation. Herein, we report light-induced switching of reaction pathways of CO 2 hydrogenation towards CH 3OH production over actomically dispersed Co decorated Pt@UiO-66-NH 2. CO, being the main product in the reverse water gas shift (RWGS) pathway under thermocatalysis condition, is switched to CH 3OH via the formate pathway with the assistance of light irradiation. Impressively, the space-time yield of CH 3OH in photo-assisted thermocatalysis (1916.3 μmol g cat−1 h −1) is about 7.8 times higher than that without light at 240 °C and 1.5 MPa. Mechanism investigation indicates that upon light irradiation, excited UiO-66-NH 2 can transfer electrons to Pt nanoparticles and Co sites, which can efficiently catalyze the critical elementary steps (i.e., CO 2-to-*HCOO conversion), thus suppressing the RWGS pathway to achieve a high CH 3OH selectivity. 相似文献
13.
The thin film photocatalysts were prepared from solvothermal UiO-66-NH 2 and sol-gel perovskite LaFeO 3 by a dip-coating technique. The properties of obtained catalysts were investigated by the methods of Brunauer-Emmett-Teller adsorption, XRD, SEM, FT-IR, TGA, and UV-vis spectroscopies. The results proved that the thin film of the thickness of 4.2 and 4.7 µm was successfully prepared from micro-mesoporous UiO-66-NH 2 and LaFeO 3 nanocrystals. Possessing small crystals (9-35 nm) and the band gap energy of 2.83 and 1.92 eV, respectively, UiO-66-NH 2 and LaFeO 3 are shown to be a highly active visible-light photocatalyst for photodegradation of p-xylene-contained gas. The kinetics of photocatalytic degradation of p-xylene under combined illumination of ultraviolet and visible lights over obtained UiO-66-NH 2 and LaFeO 3 thin films were carried out in a gradientless flow circulating system at room temperature and atmospheric pressure. The results showed that the Langmuir-Hinshelwood kinetic model was successfully applied to correlate the obtained data. The kinetics of the reaction on both catalysts were found to be written by the fractional equation, describing the dependence of the reaction rate on the concentration of p-xylene, oxygen molecules, dissociative adsorbed water vapor, the photon flux, and the inhibition of CO 2 product. It implies that the reaction occurred at high surface coverages, molecular p-xylene, and oxygen participated in the reaction in the form of surface molecular; water—in the forms of •OH and H +. Although there is a general kinetic equation for reaction on various catalysts, the different affinities of the catalysts with the compounds present in the reaction create the kinetic feature of the reaction on each catalyst. Because of the high affinity of catalysts with water vapor, the given reactant increased the rate of p-xylene photocatalytic degradation at low concentration but inhibited it in the high concentration region. The adsorption affinity of LaFeO 3 to oxygen is higher compared to UiO-66-NH 2; then, there was an optimum concentration of oxygen in the photodegradation of p-xylene on the former, whereas in the latter monotonically increasing relationship was found. 相似文献
14.
In the present work, Fe 3O 4 nanoparticles were attached to the surface of UiO-66, a zirconium-based metal–organic framework material and the composite material formed was used to remove selenite (Se(IV)) in water. The Fe 3O 4/UiO-66 composite were assembled by a facile two-stage strategy. Benefiting from the ultra-high specific surface area of UiO-66, the Fe 3O 4/UiO-66 also had a large specific surface area, which made it easier to expose the active sites of Fe 3O 4 on the surface of UiO-66. The XPS and Mössbauer spectroscopy analysis indicated that there was charge transfer between Fe 3O 4 and UiO-66 in the Fe 3O 4/UiO-66, which made the Fe 3O 4 on the surface of UiO-66 had enhanced reductive activity. The mechanism of Fe 3O 4/UiO-66 to removed Se(IV) from the solution was further investigated by Zeta potential, FT-IR, SEM, TEM, and XPS spectra. The results indicated that the Fe 3O 4 nanoparticles on the surface of UiO-66 not only interacted with selenite through electrostatic action and inner-sphere complex but could also reduce a large amount of selenite to the insoluble Se 0. The combination of these three actions finally strengthened the removal of selenite. This study cloud promote the practical application of MOF-based composites in removing heavy metal ions. 相似文献
15.
Discrimination of physically similar molecules by porous solids represents an important yet challenging task in industrially relevant chemical separations. Precisely controlled pore dimension and/or tailored pore surface functionality are crucial to achieve high-efficiency separation. Metal-organic frameworks (MOFs) are promising candidates for these challenging separations in light of their structural diversity as well as highly adjustable pore dimension/functionality. We report here a microporous, ftw -type Zr-based MOF structure, HIAM-410 (HIAM=Hoffmann Institute of Advanced Materials), built on hexanuclear Zr 6 cluster and pyrene-1,3,6,8-tetracarboxylate (ptc 4−). Its crystallographic structure has been determined using continuous rotation electron diffraction (cRED) technique combined with Rietveld refinement against powder X-ray diffraction data, aided by low-dose high-resolution transmission electron microscopy (HRTEM) imaging. The compound features exceptional framework stability that is comparable to the prototype MOF UiO-66. Interestingly, the linker vacancies in the pristine MOF structure could be partially restored by post-synthetic linker insertion. Its separation capability of hexane isomers is enhanced substantially upon the linker vacancy engineering. The restored structure exhibits efficient splitting of monobranched and dibranched hexane isomers at both room temperature and industrially relevant temperature. 相似文献
16.
We report a general method for the synthesis of free-standing, self-assembled MOF monolayers (SAMMs) at an air–water interface using polymer-brush coated MOF nanoparticles. UiO-66, UiO-66-NH 2, and MIL-88B-NH 2 were functionalized with a catechol-bound chain-transfer agent (CTA) to graft poly(methyl methacrylate) (PMMA) from the surface of the MOF using reversible addition-fragmentation chain transfer polymerization (RAFT). The polymer-coated MOFs were self-assembled at the air–water interface into monolayer films ∼250 nm thick and capable of self-supporting at a total area of 40 mm 2. Mixed-particle films were prepared through the assembly of MOF mixtures, while multilayer films were achieved through sequential transfer of the monolayers to a glass slide substrate. This method offers a modular and generalizable route to fabricate thin-films with inherent porosity and sub-micron thickness composed of a variety of MOF particles and functionalities.We report a general method for the synthesis of free-standing, self-assembled MOF monolayers (SAMMs) at an air–water interface using polymer-brush coated MOF nanoparticles. 相似文献
17.
The selectivity control of Pd nanoparticles (NPs) in the direct CO esterification with methyl nitrite toward dimethyl oxalate (DMO) or dimethyl carbonate (DMC) remains a grand challenge. Herein, Pd NPs are incorporated into isoreticular metal–organic frameworks (MOFs), namely UiO-66-X (X=-H, -NO 2, -NH 2), affording Pd@UiO-66-X, which unexpectedly exhibit high selectivity (up to 99 %) to DMC and regulated activity in the direct CO esterification. In sharp contrast, the Pd NPs supported on the MOF, yielding Pd/UiO-66, displays high selectivity (89 %) to DMO as always reported with Pd NPs. Both experimental and DFT calculation results prove that the Pd location relative to UiO-66 gives rise to discriminated microenvironment of different amounts of interface between Zr-oxo clusters and Pd NPs in Pd@UiO-66 and Pd/UiO-66, resulting in their distinctly different selectivity. This is an unprecedented finding on the production of DMC by Pd NPs, which was previously achieved by Pd(II) only, in the direct CO esterification. 相似文献
18.
Composites of metal-organic frameworks and carbon materials have been suggested to be effective materials for the decomposition of chemical warfare agents. In this study, we synthesized UiO-66-NH 2/zeolite-templated carbon (ZTC) composites for the adsorption and decomposition of the nerve agents sarin and soman. UiO-66-NH 2/ZTC composites with good dispersion were prepared via a solvothermal method. Characterization studies showed that the composites had higher specific surface areas than pristine UiO-66-NH 2, with broad pore size distributions centered at 1–2 nm. Owing to their porous nature, the UiO-66-NH 2/ZTC composites could adsorb more water at 80% relative humidity. Among the UiO-66-NH 2/ZTC composites, U 0.8Z 0.2 showed the best degradation performance. Characterization and gas adsorption studies revealed that beta-ZTC in U 0.8Z 0.2 provided additional adsorption and degradation sites for nerve agents. Among the investigated materials, including the pristine materials, U 0.8Z 0.2 also exhibited the best protection performance against the nerve agents. These results demonstrate that U 0.8Z 0.2 has the optimal composition for exploiting the degradation performance of pristine UiO-66-NH 2 and the adsorption performance of pristine beta-ZTC. 相似文献
19.
Metal-organic frameworks (MOFs) have been shown to be an excellent platform in photocatalysis. However, to suppress electron–hole recombination, a Pt cocatalyst is usually inevitable, especially in photocatalytic H 2 production, which greatly limits practical application. Herein, for the first time, monodisperse, small-size, and noble-metal-free transitional-metal phosphides (TMPs; for example, Ni 2P, Ni 12P 5), are incorporated into a representative MOF, UiO-66-NH 2, for photocatalytic H 2 production. Compared with the parent MOF and their physical mixture, both TMPs@MOF composites display significantly improved H 2 production rates. Thermodynamic and kinetic studies reveal that TMPs, behaving similar ability to Pt, greatly accelerate the linker-to-cluster charge transfer, promote charge separation, and reduce the activation energy of H 2 production. Significantly, the results indicate that Pt is thermodynamically favorable, yet Ni 2P is kinetically preferred for H 2 production, accounting for the higher activity of Ni 2P@UiO-66-NH 2 than Pt@UiO-66-NH 2. 相似文献
20.
Mixed-matrix membranes (MMMs) with combination of two distinct dimensional nanofillers (such as 1D-3D, 2D-3D, or 3D-3D, etc.) have drawn special attention for gas separation applications due to their concerted effects on gas permeation and mechanical properties. An amine-functionalized 1D multiwalled carbon nanotube (NH 2-MWCNT) with exceptional mechanical strength and rapid gas transport was crosslinked with an amine-functionalized 3D metal-organic framework (UiO-66-NH 2) with high CO 2 affinity in a Schiff base reaction. The resultant crosslinked mixed-dimensional nanostructure was used as a nanofiller in a polysulfone (PSf) polymer matrix to explore the underlying synergy between 1D and 3D nanostructures on the gas separation performance of MMMs. Cross-sectional scanning electron microscopy and mapping revealed the homogenous dispersion of UiO-66@MWCNT in the polymer matrix. The MMM containing 5.0 wt. % UiO-66@MWCNT demonstrated a superior permeability 8.3 Barrer as compared to the 4.2 Barrer of pure PSf membrane for CO 2. Moreover, the selectivity (CO 2/CH 4) of this MMM was enhanced to 39.5 from the 28.0 observed for pure PSf under similar conditions of pressure and temperature. 相似文献
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