A facile and scalable synthetic method for covalent organic nanosheets: ultrasonic polycondensation and photocatalytic degradation of organic pollutants

Gan, Shi-Xian; Jia, Chao; Qi, Qiao-Yan; Zhao, Xin

doi:10.1039/d1sc05504f

Cited by 31 publications

(22 citation statements)

References 69 publications

(74 reference statements)

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“…Such decreases of surface area can be ascribed to lack of longrange stacking of layers, which has been well-known in other exfoliated nanosheets. 40 Heterogeneous Catalysis. The hydroboration of alkynes is widely used for synthesizing vinylboranes, which are frequently involved in several important organic transformations, medicinal chemistry, and advanced materials.…”

Section: Syntheses Characterization and Chemical Stabilitymentioning

confidence: 84%

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Ultrathin Metal–Organic Framework Nanosheets Exhibiting Exceptional Catalytic Activity

et al. 2022

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Two-dimensional (2D) metal–organic framework nanosheets (MONs) or membranes are classes of periodic, crystalline polymeric materials that may show unprecedented physicochemical properties due to their modular structures, high surface areas, and high aspect ratios. Yet preparing 2D MONs from multiple components and two different types of polymerization reaction remains challenging and less explored. Here, we report the synthesis of MOF films via interfacial polymerization, which involves three active monomers for simultaneous polycondensation and polycoordination taking place in a confined interface. The well-defined lamellar structure of the MOF films allowed feasible and scalable exfoliation to produce free-standing 2D MONs with high aspect ratio up to 2000:1 and ultrathin thickness (∼1.7 nm). The pore structure was revealed by high-resolution TEM images with near-atomic precision. The imide-linkage of MONs provided superior thermal (up to 530 °C) and good chemical stability in the pH range from 3 to 12. More importantly, the MONs exhibited exceptional catalytic activity and superior reusability for the hydroboration reactions of alkynes, in which the turnover frequency (TOF) reached 41734 h–1, which is 2–4 orders of magnitude greater than that reported for homogeneous and heterogeneous catalysts.

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Section: Syntheses Characterization and Chemical Stabilitymentioning

confidence: 84%

“…Furthermore, JNM-4-Ns displayed a BET value of 800.7 m 2 g –1 with a unified pore size of ∼2.83 nm, which was smaller than those of 3D- and 2D-JNM-4 (Figure f). Such decreases of surface area can be ascribed to lack of long-range stacking of layers, which has been well-known in other exfoliated nanosheets …”

Section: Resultsmentioning

confidence: 99%

Ultrathin Metal–Organic Framework Nanosheets Exhibiting Exceptional Catalytic Activity

et al. 2022

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“…The mechanical pulverzation did not alter the chemical integrity of the COF as the FTIR spectrum of dDAAQ-TFP was similar to the parent COF. 17 Solid state 13 C CP-MAS NMR spectroscopy of dDAAQ-TFP was performed (Figure 1b). The characteristic signals at 118 ppm (=CNH, α-enamine), 144 ppm (C*=CNH, β -enamine) and 181 ppm (C=O, carbonyl group) can be assigned to the presence of β-ketoenamine-linkage.…”

Section: Resultsmentioning

confidence: 99%

“…During the analysis, a magnetic field of 11.7 T was externally applied. By using linearly ramped cross-polarization with Magic-angle spinning (CP-MAS) at 125.79 MHz, 13 C NMR spectra was evaluated. The CP contact time, flip angle, and pulse width were all set at 2 ms, 90°, and 3.84 s, respectively.…”

Section: Characterizationmentioning

confidence: 99%

“…However, the notion of extended conjugation, decreased electron-hole recombination, and suppressed photo-corrosion are the only known strategies for improving the photocatalytic activities of novel COF-based materials. This includes functional group or side chain modulation, 9 elemental doping of non-metals 10 and metals 11 incorporation of light sensitizing co-catalyst 12 , nanoconfining, 13 construction of hybrid structures are believed to provide versatile strategies for improved photocatalysis. 14 Through effective charge carrier separation and hence mobility, COF materials can be carefully designed to easily improve photocatalytic performance.…”

Section: Introductionmentioning

confidence: 99%

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Mechanically Activated Covalent Organic Framework as Metal Free Photocatalyst for Continuous Flow Fenton-like Degradation of Organic Pollutants and Hexavalent Chromium Reduction

Gogoi

Jena

Singh

et al. 2023

Preprint

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A highly active photocatalyst is unveiled for the Fenton-like reactions in visible light. A metal-free covalent organic framework (COF) was highly active via a novel mechanical pulverization process. Under visible light, the activity of pulverized COF reached an apparent quantum yield of 41% for Fenton-like degradation. The exceptional performance is due to the conduction band's induced high excited electron density. The outstanding performance does not require pH adjustment by external means, unlike metal-based photocatalysts. The pulverized COF can be recycled up to five times. For industrial scale implementation, the photocatalyst outperformed in a continuous flow channel. The photocatalytic space-time yield (PSTY) was increased by 28 times over conventional batch photocatalysis. For successful chemical reactions, an exceedingly small amount of photocatalyst is required. Additionally, a very high photoreduction rate was also observed for hexavalent chromium, which was significantly better than the parent COF.

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Transformation of an Imine Cage to a Covalent Organic Framework Film at the Liquid–Liquid Interface

et al. 2023

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Dynamic covalent chemistry (DCC) opens up a fascinating route for the construction of well‐organized supramolecular architectures, starting from organic molecular cages to crystalline macromolecular covalent organic frameworks (COFs). Herein, for the first time, we have manifested a facile room‐temperature DCC‐directed transformation of discrete organic imine cage‐to‐COF film at the liquid–liquid interface. The unfolding of the cage leading to the generation of imine intermediates, followed by their interface‐assisted preorganization and subsequent growth of the COF film, are elucidated through detailed spectroscopic and microscopic investigations. The interfacial cage‐to‐COF transformation provides a facile route for the faster fabrication of free‐standing COF films with high porosity and crystallinity, demonstrating excellent performance towards molecular sieving and high solvent permeance. Thus, the current study opens up a new route for structural interconversion between two crystalline entities with diverse dimensionality employing DCC at the confined interface.

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A facile and scalable synthetic method for covalent organic nanosheets: ultrasonic polycondensation and photocatalytic degradation of organic pollutants

Abstract: Covalent organic framework nanosheets (COF NSs or CONs), as compared to their bulk counterparts two-dimensional (2D) covalent organic frameworks (COFs), exhibit superior performance in many aspects due to their fully...

Cited by 31 publications

References 69 publications

Ultrathin Metal–Organic Framework Nanosheets Exhibiting Exceptional Catalytic Activity

Ultrathin Metal–Organic Framework Nanosheets Exhibiting Exceptional Catalytic Activity

Mechanically Activated Covalent Organic Framework as Metal Free Photocatalyst for Continuous Flow Fenton-like Degradation of Organic Pollutants and Hexavalent Chromium Reduction

Transformation of an Imine Cage to a Covalent Organic Framework Film at the Liquid–Liquid Interface

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