In Situ Synthesis of Chemically Bonded 2D/2D Covalent Organic Frameworks/O‐Vacancy WO₃ Z‐Scheme Heterostructure for Photocatalytic Overall Water Splitting

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(33)

Published: June 15, 2023

Abstract Covalent organic frameworks (COFs) have shown great promise for photocatalytic hydrogen evolution via water splitting. However, the four‐electron oxidation of remains elusive toward oxygen evolution. Enabling this pathway is critical to improve yield and maximize atom utilization efficiency. A Z‐scheme heterojunction proposed overcoming fundamental issues in COF‐based overall splitting (OWS), such as inefficient light absorption, charge recombination, poor ability. It that construction a novel 2D/2D through situ growth COFs on O‐vacancy WO 3 nanosheets (Ov‐WO ) WOC chemical bond can remarkably promote OWS. Benefiting from synergistic effect between enhanced built‐in electric field by interfacial bond, strong ability Ov‐WO 3, ultrathin structure TSCOF, both separation efficiency photogenerated electron–hole pairs be significantly enhanced. An impressive half‐rection rate 593 mmol h −1 g 146 (hydrogen) 68 (oxygen) µmol are achieved COF‐WO (TSCOFW) composite. This with two‐step excitation precisely cascaded charge‐transfer makes it responsible efficient solar‐driven OWS without sacrificial agent.

Language: Английский

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Efficient Adsorption of Acetylene over CO₂ in Bioinspired Covalent Organic Frameworks

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(33), P. 14992 - 14996

Published: Aug. 5, 2022

Rational design of covalent organic frameworks (COFs) to broaden their diversity is highly desirable but challenging due the limited, expensive, and complex building blocks, especially compared with other easily available porous materials. In this work, we fabricated two novel bioinspired COFs, namely, NUS-71 NUS-72, using reticular chemistry ellagic acid triboronic acid-based blocks. Both COFs AB stacking mode exhibit high acetylene (C2H2) adsorption capacity excellent separation performance for C2H2/CO2 mixtures, which significant rarely explored COFs. The impressive affinities C2H2 appear be related sandwich structure formed by host framework via multiple host–guest interactions. This work not only represents a new avenue construction low-cost also expands variety COF family natural biochemicals as blocks broad application.

Language: Английский

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Covalent Organic Frameworks as Porous Pigments for Photocatalytic Metal-Free C–H Borylation

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7592 - 7599

Published: March 21, 2023

Covalent organic frameworks (COFs) are highly promising as heterogeneous photocatalysts due to their tunable structures and optoelectronic properties. Though COFs have been used photocatalysts, they mainly employed in water splitting, carbon dioxide reduction, hydrogen evolution reactions. A few examples synthesis using metal-anchored COF were reported. Herein, we report stable β-keto-enamine-based for metal-free C–B bond formation Three different availed this purpose. Their photocatalysis performances monitored 12 substrates, like quinolines, pyridines, pyrimidines. All the showcase moderate-to-high yields (up 96%) depending upon substrate's molecular functionality. High crystallinity, a large surface area, low band gap, suitable position result highest catalytic activity of TpAzo COF. The thorough mechanistic investigation further highlights crucial role light-harvesting capacity, charge separation efficiency, current density during catalysis. light absorbance capacity plays critical catalysis maximized near COF's absorption maxima. high photostability as-synthesized offers reusability several (>5) cycles.

Language: Английский

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Highly Crystalline Polyimide Covalent Organic Framework as Dual-Active-Center Cathode for High-Performance Lithium-Ion Batteries

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(51), P. 23534 - 23542

Published: Dec. 13, 2022

Polyimide covalent organic framework (PI-COF) materials that can realize intrinsic redox reactions by changing the charge state of their electroactive sites are considered as emerging electrode for rechargeable devices. However, highly crystalline PI-COFs with hierarchical porosity less reported due to rapid reaction between monomers and poor reversibility polyimidization reaction. Here, we developed a water-assistant synthetic strategy adjust rate polyimidization, PI-COF (COFTPDA-PMDA) kgm topology consisting dual active centers N,N,N′,N′-tetrakis(4-aminophenyl)-1,4-benzenediamine (TPDA) pyromellitic dianhydride (PMDA) ligands was successfully synthesized high crystallinity porosity. The COFTPDA-PMDA possesses micro-/mesoporous channels largest surface area (2669 m2/g) in PI-COFs, which promote Li+ ions bulky bis(trifluoromethanesulfonyl)imide (TFSI–) electrolyte sufficiently interact on COF skeleton increase specific capacity cathode materials. As material lithium-ion batteries, COFTPDA-PMDA@50%CNT integrated center carbon nanotubes via π–π interactions gave initial 233 mAh/g (0.5 A/g) maintains at 80 even current density 5.0 A/g after 1800 cycles.

Language: Английский

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Covalent Organic Frameworks Enable Sustainable Solar to Hydrogen Peroxide

Advanced Functional Materials, Journal Year: 2023, Volume and Issue: 34(12)

Published: Dec. 6, 2023

Abstract As a chemical product with rapidly expanding demand in the field of modern energy and environmental applications, hydrogen peroxide (H 2 O ) has garnered widespread attention. However, existing industrial production H is plagued by high consumption, harmful waste emission, severe safety issues, making it difficult to satisfy environmental/economic concept. Artificial photosynthesis offers viable strategy for green sustainable since uses sunlight as an source initiate reaction oxygen water produce . Among various photocatalysts, covalent organic frameworks (COFs), featuring highly ordered skeletons well‐defined active sites, have emerged promising photocatalysts production. This review presents nascent burgeoning area photocatalytic based on COFs. First, brief overview technology provided, followed detailed introduction principles evaluation generation. Subsequently, latest research progress judicious design COFs expounded, particular emphasis manipulating electronic structures redox sites. Finally, outlook challenges future opportunities proposed, hope stimulating further explorations novel molecular‐designed photosynthesis.

Language: Английский

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Outstanding Charge Mobility by Band Transport in Two-Dimensional Semiconducting Covalent Organic Frameworks

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(16), P. 7489 - 7496

Published: April 14, 2022

Two-dimensional covalent organic frameworks (2D COFs) represent a family of crystalline porous polymers with long-range order and well-defined open nanochannels that hold great promise for electronics, catalysis, sensing, energy storage. To date, the development highly conductive 2D COFs has remained challenging due to finite π-conjugation along lattice charge localization at grain boundaries. Furthermore, transport mechanism within framework remains elusive. Here, time- frequency-resolved terahertz spectroscopy reveals intrinsically Drude-type band carriers in semiconducting COF thin films condensed by 1,3,5-tris(4-aminophenyl)benzene (TPB) 1,3,5-triformylbenzene (TFB). The TPB-TFB demonstrate high photoconductivity long scattering time exceeding 70 fs room temperature which resembles inorganic materials. This corresponds record carrier mobility 165 ± 10 cm2 V-1 s-1, vastly outperforming state-of-the-art COFs. These results reveal as promising candidates electronics catalysis provide insights into rational design materials efficient transport.

Language: Английский

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Exceptionally high charge mobility in phthalocyanine-based poly(benzimidazobenzophenanthroline)-ladder-type two-dimensional conjugated polymers

Nature Materials, Journal Year: 2023, Volume and Issue: 22(7), P. 880 - 887

Published: June 19, 2023

Abstract Two-dimensional conjugated polymers (2DCPs), composed of multiple strands linear with extended in-plane π-conjugation, are emerging crystalline semiconducting for organic (opto)electronics. They represented by two-dimensional π-conjugated covalent frameworks, which typically suffer from poor π-conjugation and thus low charge carrier mobilities. Here we overcome this limitation demonstrating two phthalocyanine-based poly(benzimidazobenzophenanthroline)-ladder-type 2DCPs (2DCP-MPc, M = Cu or Ni), constructed octaaminophthalocyaninato metal( ii ) naphthalenetetracarboxylic dianhydride polycondensation under solvothermal conditions. The 2DCP-MPcs exhibit optical bandgaps ~1.3 eV highly delocalized π-electrons. Density functional theory calculations unveil strongly dispersive energy bands small electron–hole reduced effective masses ~0.15 m 0 the layer-stacked 2DCP-MPcs. Terahertz spectroscopy reveals band transport Drude-type free carriers in exceptionally high sum mobility electrons holes ~970 cm 2 V −1 s at room temperature, surpassing that reported 2DCPs. This work highlights critical role conjugation enhancing properties great potential high-mobility future

Language: Английский

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Covalent Organic Framework Thin-Film Photodetectors from Solution-Processable Porous Nanospheres

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(3), P. 1649 - 1659

Published: Jan. 9, 2023

The synthesis of homogeneous covalent organic framework (COF) thin films on a desired substrate with decent crystallinity, porosity, and uniform thickness has great potential for optoelectronic applications. We have used solution-processable sphere transmutation process to synthesize 300 ± 20 nm COF 2 × cm2 TiO2-coated fluorine-doped tin oxide (FTO) surface. This controls the nucleation crystallites molecular morphology that helps nanospheres arrange periodically form films. synthesized four (TpDPP, TpEtBt, TpTab, TpTta) different functional backbones. In close agreement between experiment density theory, TpEtBr film showed lowest optical band gap (2.26 eV) highest excited-state lifetime (8.52 ns) among all Hence, can participate in efficient charge generation separation. constructed devices having glass/FTO/TiO2/COF-film/Au architecture, which serves as model system study transport properties under dark illuminated conditions. Visible light calibrated intensity 100 mW cm-2 was excitation All exhibit significant photocurrent after illumination visible comparison dark. behave good photoactive substrates minimal pinhole defects. fabricated out-of-plane photodetector device based exhibits high (2.65 0.24 mA at 0.5 V) hole mobility (8.15 0.64 ×10-3 V-1 S-1) compared other as-synthesized films, indicating best characteristics.

Language: Английский

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Fluorenone-based covalent organic frameworks with efficient exciton dissociation and well-defined active center for remarkable photocatalytic hydrogen evolution

Applied Catalysis B Environment and Energy, Journal Year: 2023, Volume and Issue: 330, P. 122581 - 122581

Published: March 7, 2023

Language: Английский

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Non‐Interpenetrated 3D Covalent Organic Framework with Dia Topology for Au Ions Capture

Advanced Functional Materials, Journal Year: 2023, Volume and Issue: 33(33)

Published: April 23, 2023

Abstract The 3D covalent organic frameworks (COFs) have attracted considerable attention owing to their unique structural characteristics. However, most of COFs interpenetration phenomena, which will result in decreased surface area and porosities, thus limited applications molecular/gas capture. Developing with non‐fold is challenging but significant because the existence non‐covalent interactions between adjacent nets. Herein, a new COF (BMTA‐TFPM‐COF) dia topology for Au ion capture first demonstrated. constructed exhibits high Brunauer–Emmett–Teller 1924 m 2 g −1 , pore volume 1.85 cm 3 . abundant cavities as well exposed CN linkages due non‐interpenetration enable absorb 3+ capacity (570.18 mg ), selectivity (99.5%), efficiency (68.3% adsorption maximum 5 min). This work provides strategy design

Language: Английский

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