The triboelectric nanogenerator (TENG) offers a simple and cost‐effective method to harness waste energy and works on the principle of contact electrification and electrostatic induction. The ...performance and application of TENG depend to a great extent on the material used for fabrication. The most widely used materials include polymers and a few metals, well‐arranged in the triboelectric series so as to promote electrification upon contact. New triboelectric materials are important for extending the applications and specificity of the TENG. A TENG based on a metal–organic framework (MOF) of the zeolitic imidazole family is reported here. The zeolitic imidazole framework‐8 (ZIF‐8) and Kapton are used as the active materials for MOF–TENG fabrication. Surface potential, structural, morphological and electrical measurements reveals detailed characteristics of ZIF‐8, confirming the MOF as a potential candidate for TENG applications. The MOF–TENG generates a sustainable output of 164 V and 7 µA in vertical contact–separation mode. Finally, a self‐powered UV counterfeit system and a tetracycline sensor are successfully developed and demonstrated with the MOF–TENG. The sensor is highly selective and reusable simply by washing.
The zeolitic imidazole framework‐8 (ZIF‐8) based triboelectric nanogenerator (TENG)for self‐powered sensors and systems is demonstrated. The ZIF‐8 has a high surface area, porosity, chemical, and thermal stability. The device output is 164 V and 7 μA. The device is used to drive a commercial temperature sensor, a UV counterfeit system and a tetracycline sensor.
During the last decade, the synthesis and application of metal–organic framework (MOF) nanosheets has received growing interest, showing unique performances for different technological applications. ...Despite the potential of this type of nanolamellar materials, the synthetic routes developed so far are restricted to MOFs possessing layered structures, limiting further development in this field. Here, a bottom‐up surfactant‐assisted synthetic approach is presented for the fabrication of nanosheets of various nonlayered MOFs, broadening the scope of MOF nanosheets application. Surfactant‐assisted preorganization of the metallic precursor prior to MOF synthesis enables the manufacture of nonlayered Al‐containing MOF lamellae. These MOF nanosheets are shown to exhibit a superior performance over other crystal morphologies for both chemical sensing and gas separation. As revealed by electron microscopy and diffraction, this superior performance arises from the shorter diffusion pathway in the MOF nanosheets, whose 1D channels are oriented along the shortest particle dimension.
A bottom‐up surfactant‐assisted synthetic approach to synthesize nanosheets of various nonlayered metal–organic frameworks (MOFs) is reported. The surfactant‐assisted preorganization of the metallic precursor prior to MOF synthesis enables the manufacture of nonlayered Al‐containing MOF lamellae. These MOF nanosheets are shown to exhibit a superior performance over other crystal morphologies in different molecular recognition applications.
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•Two types of magnetic Co-carbon composites are prepared from Co-based MOFs.•Both composites are active in catalyzing the reduction of p-nitrophenol.•N containing Co-carbon shows ...better performance in catalyzing the reaction.
Two types of magnetic cobalt-carbon composites were synthesized via one-step calcination of cobalt-based metal organic frameworks (MOFs), ZIF-67 and Co3(BTC)3·12H2O, and applied as catalysts in the reduction of p-nitrophenol by NaBH4. The MOFs precursors were respectively structured by using 2-methylimidazole (ZIF-67) and 1,3,5-benzenetricarboxylic acid (Co3(BTC)3·12H2O) organic linkers. Calcination of ZIF-67 produced a Co-carbon composite containing N species (Co-NCC), while Co3(BTC)3·12H2O produced a simple Co-carbon composite (Co-CC). The prepared composites were characterized by a series of spectroscopic instruments and a surface analyzer. Raman spectra of the composites suggested carbons in both composites are present as graphitic oxide phases. Surface analyses indicated Co-NCC is highly porous with surface area of 298m2g−1, and Co-CC has less porosity of 110m2g−1. Both catalysts were active in catalyzing the reduction of p-nitrophenol to p-aminophenol, but Co-NCC exhibited much better performance to give pseudo-first-order rate constant 6.7 times greater than Co-CC, and robust reusability to complete five cycles of p-nitrophenol reduction with minimal loss of catalytic capability. The superior catalytic property of Co-NCC is attributed to the presence of N-moieties that provided additional reduction sites along with considerable porosity of the material.
•The experimental and computational techniques for proton-conductive MOFs are summarized.•Representative studies are reviewed on the tuning of proton conductivity of MOFs.•Perspectives toward the ...modulation on the proton conductivity of MOFs are presented.
Over the past decades, research on proton-conductive metal-organic frameworks (MOFs) has rapidly accelerated due to the importance of energy for modern society. This review mainly focuses on some representative proton-conductive MOFs reported recently, with related discussions on the underlying proton transportation mechanisms. In the first section, we give a brief introduction to the background of proton-conductive MOFs. In the following second section, a summarization on the widely used experimental characterization techniques as well as the well-established computational methods for exploring the proton transportation mechanism is given. In the third section, some representative studies in this field are reviewed from the aspect that how to tune the proton conductivity of MOFs, with emphasis on the following factors: the impact of framework and guest molecules/ions; the modification with functionalized groups and the tuning of Brønsted acidity; the influence of phase transition, defects, and amorphization. Finally, the conclusion and perspective are presented regarding the modulation on the proton conductivity of MOFs and the rational design of novel proton-conductive MOFs.
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•Defective UiO-66 was prepared by modulated synthesis and acid treatment.•The defective UiO-66 shows highest surface area among all the reported UiO-66.•The defective UiO-66 shows ...high adsorption capacity for Safranin T.•The defective UiO-66 shows high selectivity for Safranin T over Crystal Violet.
In this work, UiO-66 with defects was successfully prepared by a synthesis strategy of using benzoic acid as a modulator and postsynthetic acid treatment. The defective frameworks can be confirmed by N2 adsorption–desorption analysis and 1H NMR. It is observed that this strategy can effectively enlarge the surface area and pore volume of stable UiO-66 through the removal of coordinated benzoate ligands. The resulting defective UiO-66 shows high BET surface area and total pore volume (1890m2/g and 0.88cm3/g), which are both larger than those of defect-free sample (1200m2/g and 0.49cm3/g) as well as all the reported UiO-66s with defects so far to the best of our knowledge. This MOF exhibits significantly improved capture ability (366mg/g) toward Safranine T (ST) compared with the defect-free UiO-66 (39mg/g) and most of reported adsorbents. Meanwhile, it also shows high selectivity for ST over Crystal Violet (CV) due to the size-exclusion effect constructed from the defects in the framework. The results show that this work provides a promising strategy to rationally design novel MOFs for separating large molecules.
Heterostructural metal/metal oxides are the very promising substituents of noble‐metal catalysts; however, generation and further stabilization of accessible metal/metal oxide heterojunctions are ...very difficult. A strategy to encapsulate and stabilize Cu/Cu2O nanojunctions in porous organic frameworks in situ is developed by tuning the acrylate contents in copper‐based metal–organic frameworks (Cu‐MOFs) and the pyrolytic conditions. The acrylate groups play important roles on improving the polymerization degree of organic frameworks and generating and stabilizing highly dispersed and accessible Cu/Cu2O heteronanojunctions. As a result, pyrolysis of the MOF ZJU‐199, consisting of three acrylates per ligand, generates abundant heterostructural Cu/Cu2O discrete domains inside porous organic matrices at 350 °C, demonstrating excellent catalytic properties in liquid‐phase hydrogenation of furfural into furfuryl alcohol, which are much superior to the non‐noble metal‐based catalysts.
A strategy to generate and stabilize Cu/Cu2O nanojunctions inside porous organic frameworks is developed by controlled pyrolysis of metal–organic frameworks. This results in a composite material that consists of easily accessed Cu/Cu2O heterojunctions inside porous organic matrices that exhibit excellent catalytic properties in the hydrogenation of furfural into furfuryl alcohol.
Here we discuss the removal of nitrogen dioxide, an important toxic industrial chemical and pollutant, from air using the MOF UiO‐66‐NH2. The amine group is found to substantially aid in the removal, ...resulting in unprecedented removal capacities upwards of 1.4 g of NO2 /g of MOF. Furthermore, whereas NO2 typically generates substantial quantities of NO on sorbents, the amount generated by UiO‐66‐NH2 is significantly reduced. Of particular significance is the formation of a diazonium ion on the aromatic ring of the MOF, and the potential reduction of NO2 to molecular nitrogen.
Clean air with MOF: The metal–organic framework UiO‐66‐NH2 was used to remove toxic nitrogen dioxide from streams of air with only small amounts of nitric oxide formed. The highly efficient reaction was due to formation of several nitrate species, as well as a diazonium ion on the MOF secondary building unit. It is also possible that molecular nitrogen was formed during the reaction.
New mechanisms for the controlled growth of one‐dimensional (1D) metal–organic framework (MOF) nano‐ and superstructures under size‐confinement and surface‐directing effects have been discovered. ...Through applying interfacial synthesis templated by track‐etched polycarbonate (PCTE) membranes, congruent polycrystalline zeolitic imidazolate framework‐8 (ZIF‐8) solid nanorods and hollow nanotubes were found to form within 100 nm membrane pores, while single crystalline ZIF‐8 nanowires grew inside 30 nm pores, all of which possess large aspect ratios up to 60 and show preferential crystal orientation with the {100} planes aligned parallel to the long axis of the pore. Our findings provide a generalizable method for controlling size, morphology, and lattice orientation of MOF nanomaterials.
Templated interfacial synthesis was applied to metal–organic framework (MOF) growth under both size‐confinement and surface‐directing effects. This led to congruent polycrystalline MOF nanorods and nanotubes, and single crystalline nanowires with large aspect ratios up to 60 and controlled crystal lattice orientation.
Metal‐organic frameworks (MOFs) hybridized with a conductive matrix could potentially serve as a sulfur host for lithium‐sulfur (Li‐S) battery electrodes; so far most of the previously studied hybrid ...structures are in the powder form or thin compact films. This study reports 3D porous MOF@carbon nanotube (CNT) networks by grafting MOFs with tailored particle size uniformly throughout a CNT sponge skeleton. Growing larger‐size MOF particles to entrap the conductive CNT network yields a mutually embedded structure with high stability, and after sulfur encapsulation, it shows an initial discharge capacity of ≈1380 mA h g−1 (at 0.1 C) and excellent cycling stability with a very low fading rate. Furthermore, owing to the 3D porous network that is suitable for enhanced sulfur loading, a remarkable areal capacity of ≈11 mA h cm−2 (at 0.1 C) is obtained, which is much higher than other MOF‐based hybrid electrodes. The mutually embedded MOF@CNTs with simultaneously high specific capacity, areal capacity, and cycling stability represent an advanced candidate for developing high‐performance Li‐S batteries and other energy storage systems.
Metal‐organic framework particles with tailored size are in situ grown in a carbon nanotube sponge template to form a 3D porous electrode with a distinct mutually embedded structure, which shows enhanced sulfur loading and superior structural stability, resulting simultaneously in high specific capacity, areal capacity, and cycling stability in lithium‐sulfur battery applications.
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