Tuning excited state electronic structure and charge transport in covalent organic frameworks for enhanced photocatalytic performance

Nature Communications, Год журнала: 2023, Номер 14(1)

Опубликована: Фев. 27, 2023

Covalent organic frameworks (COFs) represent an emerging class of photocatalysts. However, their complicated structures lead to indeterminacy about photocatalytic active sites and reaction mechanisms. Herein, we use reticular chemistry construct a family isoreticular crystalline hydrazide-based COF photocatalysts, with the optoelectronic properties local pore characteristics COFs modulated using different linkers. The excited state electronic distribution transport pathways in are probed host experimental methods theoretical calculations at molecular level. One our developed (denoted as COF-4) exhibits remarkable electron utilization efficiency charge transfer properties, achieving record-high uranium extraction performance ~6.84 mg/g/day natural seawater among all techniques reported so far. This study brings new understanding operation COF-based guiding design improved photocatalysts for many applications.

Язык: Английский

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Computation-based regulation of excitonic effects in donor-acceptor covalent organic frameworks for enhanced photocatalysis

Nature Communications, Год журнала: 2023, Номер 14(1)

Опубликована: Май 29, 2023

The strong excitonic effects widely exist in polymer-semiconductors and the large exciton binding energy (Eb) seriously limits their photocatalysis. Herein, density functional theory (DFT) calculations are conducted to assess band alignment charge transfer feature of potential donor-acceptor (D-A) covalent organic frameworks (COFs), using 1,3,5-tris(4-aminophenyl)triazine (TAPT) or 1,3,5-tris(4-aminophenyl)benzene (TAPB) as acceptors tereph-thaldehydes functionalized diverse groups donors. Given discernable D-A interaction strengths pairs, Eb can be systematically regulated with minimum TAPT-OMe. Guided by these results, corresponding COFs synthesized, where TAPT-OMe-COF possesses best activity photocatalytic H2 production trend other is associated that calculated for pairs. In addition, further alkyne cycloaddition imine linkage greatly improves stability resulting TAPT-OMe-alkyne-COF a substantially smaller exhibits ~20 times higher than parent COF.

Язык: Английский

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Covalent Organic Frameworks for Energy Conversion in Photocatalysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(34)

Опубликована: Апрель 24, 2023

Abstract Intensifying energy crises and severe environmental issues have led to the discovery of renewable sources, sustainable conversion, storage technologies. Photocatalysis is a green technology that converts eco‐friendly solar into high‐energy chemicals. Covalent organic frameworks (COFs) are porous materials constructed by covalent bonds show promising potential for converting chemicals owing their pre‐designable structures, high crystallinity, porosity. Herein, we highlight recent progress in synthesis COF‐based photocatalysts applications water splitting, CO 2 reduction, H O production. The challenges future opportunities rational design COFs advanced discussed. This Review expected promote further development toward photocatalysis.

Язык: Английский

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

Advanced Materials, Год журнала: 2023, Номер 35(33)

Опубликована: Июнь 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.

Язык: Английский

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Reconstruction of Highly Dense Cu−N₄Active Sites in Electrocatalytic Oxygen Reduction Characterized by Operando Synchrotron Radiation

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(40)

Опубликована: Авг. 22, 2022

The emerging star of single atomic site (SAS) catalyst has been regarded as the most promising Pt-substituted electrocatalyst for oxygen reduction reaction (ORR) in anion-exchange membrane fuel cells (AEMFCs). However, metal loading SAS directly affects whole device performance. Herein, we report a dual nitrogen source coordinated strategy to realize high dense Cu-N4 with 5.61 wt% supported on 3D N-doped carbon nanotubes/graphene structure wherein simultaneously performs superior ORR activity and stability alkaline media. When applied H2 /O2 AEMFC, it could reach an open-circuit voltage 0.90 V peak power density 324 mW cm-2 . Operando synchrotron radiation analyses identify reconstruction from initial /Cu-nanoclusters (NC) subsequent Cu-N3 /Cu-NC under working conditions, which gradually regulate d-band center central balance Gibbs free energy *OOH *O intermediates, benefiting activity.

Язык: Английский

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Boosting Electroreduction of CO₂over Cationic Covalent Organic Frameworks: Hydrogen Bonding Effects of Halogen Ions

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(7)

Опубликована: Ноя. 25, 2022

We present the first example of charged imidazolium functionalized porphyrin-based covalent organic framework (Co-iBFBim-COF-X) for electrocatalytic CO2 reduction reaction, where free anions (e.g., F- , Cl- Br- and I- ) ions nearby active Co sites can stabilize key intermediate *COOH inhibit hydrogen evolution reaction. Thus, Co-iBFBim-COF-X exhibits higher activity than neutral Co-BFBim-COF, following trend

Язык: Английский

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Integrated interfacial design of covalent organic framework photocatalysts to promote hydrogen evolution from water

Nature Communications, Год журнала: 2023, Номер 14(1)

Опубликована: Янв. 19, 2023

Attempts to develop photocatalysts for hydrogen production from water usually result in low efficiency. Here we report the finding of by integrated interfacial design stable covalent organic frameworks. We predesigned and constructed different molecular interfaces fabricating ordered or amorphous π skeletons, installing ligating non-ligating walls engineering hydrophobic hydrophilic pores. This systematic control over electron transfer, active site immobilisation transport enables identify their distinct roles photocatalytic process. The frameworks, combined channels, work under 300-1000 nm with non-noble metal co-catalyst achieve a evolution rate 11 mmol g-1 h-1, quantum yield 3.6% at 600 three-order-of-magnitude-increased turnover frequency 18.8 h-1 compared those obtained networks. approach is step towards designing solar-to-chemical energy conversion systems.

Язык: Английский

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Isomeric Oligo(Phenylenevinylene)‐Based Covalent Organic Frameworks with Different Orientation of Imine Bonds and Distinct Photocatalytic Activities

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(5)

Опубликована: Дек. 1, 2022

Imine-linked covalent organic frameworks (COFs) have been extensively studied in photocatalysis because of their easy synthesis and excellent crystallinity. The effect imine-bond orientation on the photocatalytic properties COFs, however, is still rarely studied. Herein, we report two novel COFs with different orientations imine bonds using oligo(phenylenevinylene) moieties. showed similar structures but great differences photoelectric properties. COF-932 demonstrated a superior hydrogen evolution performance compared to COF-923 when triethanolamine was used as sacrificial agent. Interestingly, use ascorbic acid led protonation further altering direction electron transfer. performances were increased 23.4 0.73 mmol g-1 h-1 for protonated COF-932, respectively. This study provides clear strategy design imine-linked COF-based photocatalysts advances development COFs.

Язык: Английский

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Covalent organic frameworks in heterogeneous catalysis: recent advances and future perspective

Materials Chemistry Frontiers, Год журнала: 2023, Номер 7(16), С. 3298 - 3331

Опубликована: Янв. 1, 2023

This review provides an overview of the recent advances in heterogeneous catalysis using COFs, primarily from 2020 to 2023, covering fundamentals, advantages, current challenges, and future perspectives.

Язык: Английский

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Photocatalytic CO2 reduction to syngas using metallosalen covalent organic frameworks

Nature Communications, Год журнала: 2023, Номер 14(1)

Опубликована: Ноя. 1, 2023

Abstract Metallosalen-covalent organic frameworks have recently gained attention in photocatalysis. However, their use CO 2 photoreduction is yet to be reported. Moreover, facile preparation of metallosalen-covalent with good crystallinity remains considerably challenging. Herein, we report a series produced via one-step synthesis strategy that does not require vacuum evacuation. possessing controllable coordination environments mononuclear and binuclear metal sites are obtained act as photocatalysts for tunable syngas production from . exhibit higher catalytic activities than those two-step synthesis. The optimal framework material containing cobalt triazine achieves rate 19.7 mmol g −1 h (11:8 H /CO), outperforming previously reported porous crystalline materials. This study provides producing high quality can accelerate exploration various applications.

Язык: Английский

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