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1.
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
2.
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
3.
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
4.
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
5.
UiO-66-NH 2-IM, a fluorescent metal-organic framework (MOF), was synthesized by post-synthetic modification of UiO-66-NH 2 with 2-imidazole carboxaldehyde via a Schiff base reaction. It was examined using various characterization techniques (PXRD, FTIR, NMR, SEM, TGA, UV-Vis DRS, and photoluminescence spectroscopy). The emissive feature of UiO-66-NH 2-IM was utilized to detect volatile organic compounds (VOCs), metal ions, and anions, such as acetone, Fe 3+, and carbonate (CO 32−). Acetone turns off the high luminescence of UiO-66-NH 2-IM in DMSO, with the limit of detection (LOD) being 3.6 ppm. Similarly, Fe 3+ in an aqueous medium is detected at LOD=0.67 μM (0.04 ppm) via quenching. On the contrary, CO 32− in an aqueous medium significantly enhances the luminescence of UiO-66-NH 2-IM, which is detected with extremely high sensitivity (LOD=1.16 μM, i. e., 0.07 ppm). Large Stern-Volmer constant, K sv, and low LOD values indicate excellent sensitivity of the post-synthetic MOF. Experimental data supported by density functional theory (DFT) calculations discern photo-induced electron transfer (PET), resonance energy transfer (RET), inner filter effect (IFE), or proton abstraction as putative sensing mechanisms. NMR and computational studies propose a proton abstraction mechanism for luminescence enhancement with CO 32−. Moreover, the optical behavior of the post-synthetic material toward analytes is recyclable. 相似文献
6.
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
7.
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
8.
The exploration of highly efficient Pd/MOF heterogeneous catalyst system for the Suzuki–Miyaura cross-coupling (SMC) reactions of aryl chlorides is still challenging. Herein, a PdCl 2/UiO-67-bpydc was successfully synthesized by immobilizing a low amount of PdCl 2 onto the zirconium-based MOF (UiO-67-bpydc). PdCl 2/UiO-67-bpydc showed excellent catalytic performance and good recycle ability for the SMC reaction of aryl chlorides under an ambient condition. Furthermore, PdCl 2/UiO-67-bpydc retains the high catalytic activity even after five cycles, and exhibited excellent substrate size selectivity. 相似文献
9.
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
10.
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
11.
High quality, monolithic UiO-66-NH 2 thin films on diverse solid substrates have been prepared via a low temperature liquid phase epitaxy method. The achievement of continuous films with low defect densities and great stability against high temperatures and hot water is proven, clearly outperforming other reported types of MOF thin films. 相似文献
12.
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
13.
A robust and highly water stable series of UiO-66-drived MOFs including UiO-66-NH 2, glycidyl methacrylate functionalized UiO-66-NH 2 (UiO-66-GMA) and ethylenediamine functionalized UiO-66-NH 2 (UiO-66-EDA) were synthesized solvothermally and studied their adsorption performances toward two anti-cancer drugs, methotrexate (MTX) and curcumin (CUR) in the case of overdose. It was found that functionalizing the surface of UiO-66-NH 2 nanoparticles with different functional groups remarkably changes the adsorption capacity and the ideal adsorption selectivity of MTX over CUR. Particularly, the UiO-66-EDA exhibited the highest adsorption capacities for both drugs, 540.78 and 423.85 mg/g for MTX and CUR, respectively, because of the strong interaction between drug molecules and adsorbent via hydrogen bonding due to the existence of different polar functional groups. The kinetics of drugs adsorption was investigated by three well-known kinetic models, which the output indicates that the adsorption of both drugs onto the synthesized MOFs follow the pseudo-second-order model. Moreover, it was found that the equilibrium adsorption results were well fitted with the Langmuir isotherm models, revealing that the adsorption of both drugs onto the synthesized MOFs is a monolayer adsorption process. Further investigation illustrated that the synthesized MOFs could be easily activated and reused after four successive adsorption–desorption cycles. The output of the present work is of main important for biomedical and environmental applications of MOFs as an outstanding adsorbent for adsorption removal of hazardous drugs from contaminated aqueous solutions. 相似文献
14.
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
Precisely tuning the nuclearity of supported metal nanoclusters is pivotal for designing more superior catalytic systems, but it remains practically challenging. By utilising the chemical and molecular specificity of UiO-66-NH 2 (a Zr-based metal–organic framework), we report the controlled synthesis of supported bi- and trinuclear Cu-oxo nanoclusters on the Zr 6O 4 nodal centres of UiO-66-NH 2. We revealed the interplay between the surface structures of the active sites, adsorption configurations, catalytic reactivities and associated reaction energetics of structurally related Cu-based ‘single atoms’ and bi- and trinuclear species over our model photocatalytic formic acid reforming reaction. This work will offer practical insight that fills the critical knowledge gap in the design and engineering of new-generation atomic and nanocluster catalysts. The precise control of the structure and surface sensitivities is important as it can effectively lead to more reactive and selective catalytic systems. The supported bi- and trinuclear Cu-oxo nanoclusters exhibit notably different catalytic properties compared with the mononuclear ‘Cu 1’ analogue, which provides critical insight for the engineering of more superior catalytic systems.The controlled synthesis of novel bi- and trinuclear Cu-oxo nanoclusters supported on UiO-66-NH 2 that show notably different catalytic properties in the photocatalytic formic acid decomposition reaction is reported. 相似文献
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