Π‐Skeleton Tailoring of Olefin‐Linked Covalent Organic Frameworks Achieving Low Exciton Binding Energy for Photo‐Enhanced Uranium Extraction from Seawater

Advanced Functional Materials, Год журнала: 2023, Номер 34(1)

Опубликована: Сен. 21, 2023

Abstract Adsorption‐photocatalysis technology based on covalent organic frameworks (COFs) offers an alternative method for advancing the field of uranium extraction from seawater. When determining photocatalytic activity COFs, binding energy excitons ( E b ) functions is decisive factor. Nevertheless, majority reported COFs have a large , which seriously restricts their application in photocatalysis. Using practical π‐skeleton engineering strategy, current study synthesizes three donor‐acceptor olefin‐linked containing amidoxime units effort to minimize . Theoretical and experimental results reveal that construction planar continuous π ‐electron delocalization channels can significantly reduce promote separation electron‐hole pairs, thereby enhancing activities. Moreover, TTh‐COF‐AO with ‐skeleton donor reduced, exhibits substantially smaller (38.4 meV). Under visible light irradiation, high photo‐enhanced capacity 10.24 mg g −1 achieved natural seawater without addition sacrificial reagents, superior been date. This study, therefore, paves way development tailored, efficient photocatalysts

Язык: Английский

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Construction of Thiadiazole-Bridged sp²-Carbon-Conjugated Covalent Organic Frameworks with Diminished Excitation Binding Energy Toward Superior Photocatalysis

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(2), С. 1318 - 1325

Опубликована: Янв. 5, 2024

Sp2-carbon-conjugated covalent organic frameworks (sp2c-COFs) have emerged as promising platforms for phototo–chemical energy conversion due to their tailorable optoelectronic properties, in-plane π-conjugations, and robust structures. However, the development of sp2c-COFs in photocatalysis is still highly hindered by limited linkage chemistry. Herein, we report a novel thiadiazole-bridged sp2c-COF (sp2c-COF-ST) synthesized thiadiazole-mediated aldol-type polycondensation. The resultant sp2c-COF-ST demonstrates high chemical stability under strong acids bases (12 M HCl or 12 NaOH). electro-deficient thiadiazole together with fully conjugated planar skeleton endows superior photoelectrochemical performance charge-carrier separation migration ability. As result, when employed photocathode, exhibits significant photocurrent up ∼14.5 μA cm–2 at 0.3 V vs reversible hydrogen electrode (RHE) visible-light irradiation (>420 nm), which much higher than those analogous COFs partial imine linkages (mix-COF-SNT ∼ 9.5 cm–2) full (imi-COF-SNNT 4.9 cm–2), emphasizing importance structure–property relationships. Further temperature-dependent photoluminescence spectra density functional theory calculations demonstrate that has smaller exciton binding well effective mass comparison mix-COF-SNT imi-COF-SNNT, suggests sp2c-conjugated enhances dissociation carrier light irradiation. This work highlights design preparation photocatalytic performance.

Язык: Английский

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Structural Motifs in Covalent Organic Frameworks for Photocatalysis

Advanced Functional Materials, Год журнала: 2024, Номер unknown

Опубликована: Март 10, 2024

Abstract Covalent organic frameworks (COFs) attract significant attention due to their ordered, crystalline, porous, metal‐free, and predictable structures. These unique characteristics offer great opportunities for the diffusion transmission of photogenerated charges during photocatalysis. Currently, a considerable number COFs are used as metal‐free semiconductor photocatalysts. This review aims understand relationships between structure photocatalysis performance provides in‐depth insight into synthetic strategy improve performance. Subsequently, focuses on structural motif in sustainable photocatalytic hydrogen evolution, carbon dioxide reduction, peroxide generation, compound transformations. Last, conjunction with progress achieved challenges yet be overcome, candid discussion is undertaken regarding field COF photocatalysis, accompanied by presentation potential research avenues future directions. seeks provide readers comprehensive understanding pivotal role robust guidance innovative utilization

Язык: Английский

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Oligo(phenylenevinylene)‐Based Covalent Organic Frameworks with Kagome Lattice for Boosting Photocatalytic Hydrogen Evolution

Advanced Materials, Год журнала: 2023, Номер 36(1)

Опубликована: Окт. 2, 2023

Covalent organic frameworks (COFs) have shown great advantages as photocatalysts for hydrogen evolution. However, the effect of linkage geometry and type on extent π-electron conjugation in plane framework photocatalytic properties COFs remains a significant challenge. Herein, two Kagome (kgm) topologic oligo(phenylenevinylene)-based are designed synthesized boosting evolution via "two one" strategy. Under visible light irradiation, COF-954 with 5 wt% Pt cocatalyst exhibits high rate (HER) 137.23 mmol g

Язык: Английский

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Structural Regulation of Covalent Organic Frameworks for Catalysis

Accounts of Chemical Research, Год журнала: 2024, Номер 57(8), С. 1214 - 1226

Опубликована: Март 29, 2024

ConspectusChemical reactions can be promoted at lower temperatures and pressures, thereby reducing the energy input, by introducing suitable catalysts. Despite its significance, quest for efficient stable catalysts remains a significant challenge. In this context, addressing efficiency of stands out as paramount concern. However, challenges posed vague structure limited tailorability traditional would make it highly desirable to fabricate optimized based on understanding structure–activity relationships. Covalent organic frameworks (COFs), subclass fully designed crystalline materials formed polymerization building blocks through covalent bonds have garnered widespread attention in catalysis. The precise customizable structures COFs, coupled with attributes such high surface area facile functional modification, COFs attractive molecular platforms catalytic applications. These inherent advantages position ideal catalysts, facilitating elucidation structure-performance relationships further improving Nevertheless, there is lack systematic emphasis summary structural regulation atomic/molecular level COF Consequently, growing need summarize research field provide deep insights into COF-based catalysis promote development.In Account, we will recent advances achieved placing an design enhanced Considering unique components present fundamental principles rational This Account starts presenting overview explaining why are promising Then, introduce principle Next, following three aspects specific strategies catalysts: (1) By designing different groups integrating metal species unit, activity and/or selectivity finely modulated. (2) Regulating linkage facilitates charge transfer modulates electronic sites, accordingly, intrinsic activity/selectivity improved. (3) means pore wall/space engineering, microenvironment surrounding sites modulated optimize performance. Finally, current future developments discussed detail. provides insight toward their performance, which inspiration other heterogeneous

Язык: Английский

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Stabilizing atomic Ru species in conjugated sp2 carbon-linked covalent organic framework for acidic water oxidation

Nature Communications, Год журнала: 2024, Номер 15(1)

Опубликована: Июнь 26, 2024

Abstract Suppressing the kinetically favorable lattice oxygen oxidation mechanism pathway and triggering adsorbate evolution at expense of activity are state-of-the-art strategies for Ru-based electrocatalysts toward acidic water oxidation. Herein, atomically dispersed Ru species anchored into an stable vinyl-linked 2D covalent organic framework with unique crossed π-conjugation, termed as COF-205-Ru. The π-conjugated structure COF-205-Ru not only suppresses dissolution through strong Ru-N motifs, but also reduces state by multiple π-conjugations, thereby activating coordinated to stabilizing vacancies during process. Experimental results including X-ray absorption spectroscopy, in situ Raman powder diffraction patterns, theoretical calculations unveil activated elevated energy level O 2 p band, decreased vacancy formation energy, promoted electrochemical stability, significantly reduced barrier potential determining step Consequently, obtained displays a high mass 2659.3 A g −1 , which is 32-fold higher than commercial RuO retains long-term durability over 280 h. This work provides strategy simultaneously promote stability catalysts

Язык: Английский

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Dual–Acceptor Engineering in Pyrene‐Based Covalent Organic Frameworks for Boosting Photocatalytic Hydrogen Evolution

Advanced Energy Materials, Год журнала: 2024, Номер 14(40)

Опубликована: Июль 18, 2024

Abstract The integration of electron donor (D) and acceptor (A) units into covalent organic frameworks (COFs) has received increasing interest due to its potential for efficient photocatalytic hydrogen (H 2 ) evolution from water. Nevertheless, the advancement D–A COFs is still constrained by limited investigations on engineering, which enables highly effective charge transfer pathways in deliver photoexcited electrons a preferential orientation enhance performance. Herein, two systems with D–A–A configurations based molecular engineering strategy are proposed construct three distinct COFs. Specifically, TAPPy‐DBTDP‐COF merging one pyrene‐based benzothiadiazole acceptors realized an average H rate 12.7 mmol h −1 g under visible light, among highest ever reported typical D–A‐type COF systems. combination experimental theoretical analysis signifies crucial role dual‐acceptor arrangement promoting exciton dissociation carrier migration. These findings underscore significant structural design, conducive separation holes resulting superior activities.

Язык: Английский

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Covalent Organic Frameworks for Photocatalytic Reduction of Carbon Dioxide: A Review

ACS Nano, Год журнала: 2024, Номер 18(33), С. 21804 - 21835

Опубликована: Авг. 8, 2024

Covalent organic frameworks (COFs) are crystalline networks with extended backbones cross-linked by covalent bonds. Due to the semiconductive properties and variable metal coordinating sites, along rapid development in linkage chemistry, utilization of COFs photocatalytic CO2RR has attracted many scientists' interests. In this Review, we summarize latest research progress on for CO2 reduction. first part, present COF linkages that have been used CO2RR, discuss four mechanisms including as intrinsic photocatalysts, photosensitive motifs metalated semiconductors heterojunction photocatalysts. Then, principles structural designs functional building units stacking mode exchange. Finally, outlook challenges provided. This Review is intended give some guidance design synthesis diverse different linkages, various structures, divergent modes efficient photoreduction CO2.

Язык: Английский

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Designing Local Electron Delocalization in 2D Covalent Organic Frameworks for Enhanced Sunlight-Driven Photocatalytic Activity

ACS Catalysis, Год журнала: 2024, Номер 14(5), С. 3556 - 3564

Опубликована: Фев. 20, 2024

Electron delocalization is a versatile method to tune the electronic structure of materials for maximizing their performances. Herein, TPBD covalent organic frameworks (COFs) with controlled electron-delocalization characteristics (denoted as TPBD-R-COF, R = H, F, CN, and NO2) were synthesized by molecular engineering systematically investigate effect electron on photocatalytic performance. We found that performance can be enhanced modulating local in COFs. The activity TPBD-CN-COF more than 12 times greater TPBD-H-COF oxidative coupling amines imines, where yield product was increased from 8 99%. experimental results theoretical calculations revealed optimal electron-attracting group −CN shows highest charge separation efficiency transport rate, while excessive not better such properties. Our findings provide strategy design optimize COF-based catalysts.

Язык: Английский

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Defect Engineering Simultaneously Regulating Exciton Dissociation in Carbon Nitride and Local Electron Density in Pt Single Atoms Toward Highly Efficient Photocatalytic Hydrogen Production

Small, Год журнала: 2024, Номер 20(34)

Опубликована: Апрель 10, 2024

Abstract The high exciton binding energy ( E b ) and sluggish surface reaction kinetics have severely limited the photocatalytic hydrogen production activity of carbon nitride (CN). Herein, a hybrid system consisting nitrogen defects Pt single atoms is constructed through facile self‐assembly photodeposition strategy. Due to acceleration dissociation regulation local electron density along with introduction defects, optimized Pt‐MCT‐3 exhibits rate 172.0 µmol h −1 λ ≥ 420 nm), ≈41 times higher than pristine CN. apparent quantum yield for determined be 27.1% at nm. experimental characterizations theoretical calculations demonstrate that act as traps dissociation, resulting in decrease from 86.92 43.20 meV. Simultaneously, stronger interaction between neighboring directionally drives free electrons aggregate around atoms, tailors d ‐band Pt, forming moderate strength H* intermediates.

Язык: Английский

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