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.
Two isostructural and isomorphrous metal–organic frameworks (MOFs), namely Zn2(Brtpt)2 (bpBTD)n (1) and {Zn2 (ntpt)2 (bpBTD)∙solvent}n (2), where bpBTD = bis(pyridin-4-yl)benzothiadiazole, ...H2Brtpt = 2-bromoterephthalic acid, H2ntpt = 2-nitroterephthalic acid, with thermal stability of 355 °C for 1 and 265 °C for 2 were hydro (solvo)thermally synthesized in DMF/H2O media at 100 °C. Single-crystal X-ray diffraction analysis revealed that 1 and 2 both possess 2-fold interpenetrating pillared-layer frameworks showing pcu net topology with the point symbol of 41,263. The sufficient extra-framework void spaces are approximately 30.1 % for 1 and 32.0 % for 2 with open channels along the b axis, where the window sizes are ca. 5.51 × 3.15 Å2 in edge for the former and ca. 5.47 × 3.44 Å2 and 3.12 × 3.44 Å2 in edge for the latter. Gas adsorption isotherms revealed that thermally activated 1 and 2 both hardly adsorb N2 with very low N2 uptakes at 77 K. Comparably, the CO2 adsorption isotherms of thermally activated 1 and 2 both revealed gate-opening (two-step) sorption behaviors with an apparent hysteretic adsorption–desorption process, where the maximum uptakes are 135.4 and 171.5 cm3 g−1 STP for 1 and 2, respectively, at 195 K and P/P0 = 1. Photoluminescence studies showed that 1 and 2 both emitted bpBTD-dominated ligand-centered emissions, being as cyan and pearl aqua color fluorescence centered at λem = 467 and 495 nm, respectively, in solid-state and as cyan color fluorescence centered at λem = 455 and 458 nm, respectively, in H2O suspensions.
Two thermally stable pillared-layer frameworks showing two-fold interpenetrating pcu net in topology have been prepared; both of them are capable of hysteretic two-step CO2 adsorption and emit cyan and pearl aqua color fluorescence, respectively, in solid-state. Display omitted
•MOFs 1 and 2 are isostructural and isomorphrous and show 2-fold interpenetrating pcu nets.•MOFs 1 and 2 both show hysteretic two-step CO2 adsorption isotherms.•MOFs 1 and 2 emit cyan and pearl aqua color fluorescence, respectively, in solid-state.•MOFs 1 and 2 have tuned the functions by varying substitutes on the terephthalate ligands.
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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.
Covalent organic frameworks (COFs) are emerging porous polymers that have 2D or 3D long-range ordering. Currently available COFs are typically insoluble or decompose upon dissolution, which ...remarkably restricts their practical implementations. For 3D COFs, the achievement of noninterpenetration, which maximizes their porosity-derived applications, also remains a challenge synthetically. Here, we report the synthesis of the first highly water-soluble 3D COF (sCOF-101) from irreversible polymerization of a preorganized supramolecular organic framework through cucurbit8uril (CB8)-controlled 2 + 2 photodimerization. Synchrotron X-ray scattering and diffraction analyses confirm that sCOF-101 exhibits porosity periodicity, with a channel diameter of 2.3 nm, in both water and the solid state and retains the periodicity under both strongly acidic and basic conditions. As an ordered 3D polymer, sCOF-101 can enrich Ru(bpy)32+ photosensitizers and redox-active polyoxometalates in water, which leads to remarkable increase of their photocatalytic activity for proton reduction to produce H2.
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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.
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.
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.
•High-throughput computational screening of 4738 MOFs and 296 COFs was performed.•IL/MOFs have higher CH4/N2 selectivities than pristine MOFs.•MOF/polymer and COF/polymer composites doubled the N2 ...permeabilities of polymers.
Separating CH4/N2 mixture is challenging, and performance of the existing materials is still open to improvement. In this study, we examined both the adsorption- and membrane-based CH4/N2 separation performances of 5034 different materials, including metal organic frameworks (MOFs), covalent organic frameworks (COFs), ionic liquid (IL)/MOF composites, MOF/polymer composites, and COF/polymer composites by performing high-throughput computational screening and molecular simulations. The top performing adsorbents and membranes were identified by computing several performance evaluation metrics. Investigation of the interactions between the gas molecules, the IL, and the top MOF was performed by density functional theory (DFT) calculations. Results pointed out that the interactions between the gas molecules and the linker fragments of the MOF are stronger than their interactions with the IL. Thus, as the IL molecules are loaded into the selected top MOF, they occupy the adsorption sites of the gases, decreasing CH4 and N2 uptakes and increasing the CH4/N2 selectivity. Our results revealed that MOFs offer great potential for adsorption-based CH4/N2 separation, and IL incorporation into MOFs remarkably increases their CH4/N2 selectivities. More than 25% of MOF and 70% of the COF membranes surpassed Robeson’s upper bound because of high N2 permeabilities and outperformed conventional polymeric membranes. N2 permeabilities and selectivities of MOF/polymer and COF/polymer composites were found to be significantly higher than those of pure polymers. Our results emphasize the promises of the design and development of new MOF and COF adsorbents, membranes, and their composites with ILs and polymers for efficient CH4/N2 separation.
Anion exchange membrane fuel cells (AEMFCs) offer several advantages over proton exchange membrane fuel cells, such as the use of a non‐precious metal catalyst, but these cells suffer from various ...issues related to OH–‐conducting electrolytes, including low conductivity and the formation of K2CO3 salt. These issues need to be resolved for the widespread use of AEMFCs. Recently, many studies have focused on developing excellent ion‐conductive electrolytes using porous materials based on metal–organic and covalent organic frameworks. However, most of this research is biased toward proton‐conducting electrolytes; to the best of the authors’ knowledge, reviews addressing OH–‐conducting electrolytes using porous materials have not been reported thus far. This review discusses OH–‐conducting porous crystalline materials and their membranes in terms of different synthetic strategies, conduction mechanisms, and experimental modalities for the design and development of future anion conductive electrolytes in fuel cells.
This review provides a comprehensive overview of solid electrolytes based on crystalline porous materials and their composite materials for use in anion exchange membrane fuel cells.
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