A one-pot synthesis to graft nanocrystallites of the UiO-66-NH 2 MOF on cellulose fibers is described. The grafting process is facilitated by surface functionalization of the cellulose fibers, to express terminal carboxylate groups that act as anchoring sites to coordinate Zr(IV) ions. The stirred reaction mixture ensured rapid nucleation on the porous support surface, and the subsequent homogeneous and complete coverage of the MOF atop the substrate fibers. The method applied to filter membrane demonstrated rapid and effective removal of model contaminants, dichromate ions containing Cr(VI) and methyl orange (MO), (78.2% and 84.5% for Cr(VI) and MO removal, respectively, with in-line filtration setup) from simulated wastewater aqueous solution. This approach delineates an efficient pathway toward grafting the water stable, functional, and microporous Zr-based MOF atop porous support, with potential far reaching applications.
We present a novel approach to produce a composite of the HKUST-1 metal−organic framework (MOF) and graphene, which is suited for the fabrication of monolithic coatings of solid substrates. In order to avoid the degradation of graphene electrical properties resulting from chemical functionalization (e.g., oxidation yielding graphene oxide, GO), commercial, nonmodified graphene was utilized. The one-pot synthesis of the moldable composite material allows for a controllable loading of graphene and the tuning of porosity. Potentially, this facile synthesis can be transferred to other MOF systems. The monolithic coatings reported here exhibit high surface areas (1156−1078 m 2 /g). The electrical conductivity was high (a range of 7.6 × 10 −6 S m −1 to 6.4 × 10 −1 S m −1 ) and was found to be proportional to the graphene content. The ability to readily attain different forms and shapes of the conductive, microporous composites indicates that the MOF@G system can provide a compelling approach to access various applications of MOFs, specifically in electrochemical catalysis, supercapacitors, and sensors.
Fully exploiting the potential of enzymes in cell‐free biocatalysis requires stabilization of the catalytically active proteins and their integration into efficient reactor systems. Although in recent years initial steps towards the immobilization of such biomolecules in metal–organic frameworks (MOFs) have been taken, these demonstrations have been limited to batch experiments and to aqueous conditions. Here we demonstrate a MOF‐based continuous flow enzyme reactor system, with high productivity and stability, which is also suitable for organic solvents. Under aqueous conditions, the stability of the enzyme was increased 30‐fold, and the space–time yield exceeded that obtained with other enzyme immobilization strategies by an order of magnitude. Importantly, the infiltration of the proteins into the MOF did not require additional functionalization, thus allowing for time‐ and cost‐efficient fabrication of the biocatalysts using label‐free enzymes.
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.Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) represent a class of highly functional solid materials assembled from metal or metal/oxo nodes and di-or higher-topic organic linkers, [1,2] that continue to receive enormous attention. Due to their modular composition and the ability to access large number of topologies, [3] a huge number of different types of these porous materials, covering a broad spectrum of functionalities, has become available. In addition, combination of different types of Hetero-MOFs fabricated by employing heteroepitaxy via layer-by-layer procedures [4] allows the integration of several different functionalities in these materials, including electrical conductivity, [5] optical upconversion, [6] luminescent properties, and the ability to modulate electrical properties upon illumination with light. [7] For numerous usages of MOFs, the commonly isolated powder-form, consisting of μm-sized particles, is well suited, e. g. for gas storage [8] and water treatment applications. [9]
A 'lawn-like' distribution of interconnected zinc oxide nanorods, coated with a metalorganic compound based on zeolitic imidazolate frameworks-ZIF-8 was prepared on microstructured thin-film interdigitated Pt-electrodes forming ZnO@ZIF-8 core-shell heterostructures and investigated as gas sensor material in relation to the identical, but uncovered pure ZnO-layer. This composite combines the gas sensing properties of the metal oxide ZnO with the specific properties of the metal organic framework material which result in a distinct change of the conditions of gas sensing at the ZnO/ZIF-8-interface. Herein, for the first time it is reported that as prepared ZnO@ZIF-8 composite material is an attractive choice to reduce the cross-sensitivity to water vapour (humidity) in the gas sensing response towards propene and ethene. The observed change of sensitivity in relation to uncovered ZnO is discussed to be due to (i) the specific interaction of the ZIF-8 at the interface with the ZnO taking influence on the gas reaction processes, (ii) the diffusivity of ZIF-8 for the different gas components, and (iii) the sorption behaviour of the used gases at the ZnO interface and inside the ZIF-8 material.
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