Multicomponent Synthesis of Imidazole‐Linked Fully Conjugated 3D Covalent Organic Framework for Efficient Electrochemical Hydrogen Peroxide Production

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(49)

Published: Oct. 26, 2023

The semiconducting properties and applications of three dimensional (3D) covalent organic frameworks (COFs) are greatly hampered because their long-ranged non-conjugated skeletons relatively unstable linkages. Here, a robust imidazole-linked fully conjugated 3D framework (BUCT-COF-7) is synthesized through the one-pot multicomponent Debus-Radziszewski reaction saddle-shaped aldehyde-substituted cyclooctatetrathiophene, pyrene-4,5,9,10-tetraone, ammonium acetate. BUCT-COF-7, as metal-free catalyst, shows excellent two electron oxygen reduction (ORR) activity in alkaline medium with high hydrogen peroxide (H2 O2 ) selectivity 83.4 %. When BUCT-COF-7 cathode catalyst assembled into electrolyzer, devices showed electrochemical production rate H2 up to 326.9 mmol g-1 h-1 . accumulative amount could totally degrade dye methylene blue via Fenton for wastewater treatment. This first report about intrinsic COFs efficient synthesis , revealing promising environment-related field.

Language: Английский

---

3D Covalent Organic Frameworks from Design, Synthesis to Applications in Optoelectronics

Small, Journal Year: 2023, Volume and Issue: 20(18)

Published: Dec. 6, 2023

Covalent organic frameworks (COFs), a new class of crystalline materials connected by covalent bonds, have been developed rapidly in the past decades. However, research on COFs is mainly focused two-dimensional (2D) COFs, and three-dimensional (3D) still initial stage. In 2D bonds exist only flakes can form 1D channels, which hinder charge transport to some extent. contrast, 3D more complex pore structure thus exhibit higher specific surface area richer active sites, greatly enhance carrier transport. Therefore, compared stronger applicability energy storage conversion, sensing, optoelectronics. this review, it first introduced design principles for particular summarize development conjugated building blocks with special focus their application Subsequently, preparation COF powders thin films methods improve stability functionalization are summarized. Moreover, applications electronics outlined. Finally, conclusions future directions presented.

Language: Английский

---

Ultrathin Free‐Standing Porous Aromatic Framework Membranes for Efficient Anion Transport

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(22)

Published: March 26, 2024

Abstract Porous aromatic frameworks (PAFs) show promising potential in anionic conduction due to their high stability and customizable functionality. However, the insolubility of most PAFs presents a significant challenge processing into membranes subsequent applications. In this study, continuous PAF with adjustable thickness were successfully created using liquid‐solid interfacial polymerization. The rigid backbone stable C−C coupling endow membrane superior chemical dimensional stabilities over conventional polymer membranes. Different quaternary ammonium functionalities anchored through flexible alkyl chains tunable length. optimal exhibited an OH − conductivity 356.6 mS ⋅ cm −1 at 80 °C 98 % relative humidity. Additionally, outstanding alkaline stability, retaining 95 its after 1000 hours 1 M NaOH. To best our knowledge, is first application materials anion exchange membranes, achieving highest exceptional chemical/dimensional stability. This work provides possibility for conductive

Language: Английский

---

Construction of dangling and staggered stacking aldehyde in covalent organic frameworks for 2e⁻ oxygen reduction reaction

Carbon Neutralization, Journal Year: 2024, Volume and Issue: 3(3), P. 415 - 422

Published: March 26, 2024

Abstract Covalent organic frameworks (COFs) have been utilized as the ideal candidates to preciously construct electrocatalysts. However, highly ordered degree of COFs renders catalytic centers closely stacked, which limits utilization efficiency sites. Herein, we first constructed dangling and staggered‐stacking aldehyde (–CHO) from [4 + 3] for 2e − oxygen reduction reaction (ORR). The new unreacted ‐CHO out COFs' planes, are more easily exposed in electrolytes than sites frameworks. More importantly, these –CHO adopt staggered stacking models, thus provide larger space mass transport those with eclipsed models. In addition, by tuning triratopic linkers COFs, properties well modulated. optimized COF shows high selectivity activity ORR, H 2 O 91%, 12.2 A g −1 , respectively. theoretical calculation further reveals higher pyridine‐contained B18C6‐PTTA‐COF due promoted binding ability intermediate OOH* at carbon –CHO. This work provides us a insight into designing electrocatalysts based on COFs.

Language: Английский

---

Structural Modulation of Covalent Organic Frameworks for Efficient Hydrogen Peroxide Electrocatalysis

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(37)

Published: June 25, 2024

Abstract The electrochemical production of hydrogen peroxide (H 2 O ) using metal‐free catalysts has emerged as a viable and sustainable alternative to the conventional anthraquinone process. However, precise architectural design these electrocatalysts poses significant challenge, requiring intricate structural engineering optimize electron transfer during oxygen reduction reaction (ORR). Herein, we introduce novel covalent organic frameworks (COFs) that effectively shift ORR from four‐electron more advantageous two‐electron pathway. Notably, JUC‐660 COF, with strategically charge‐modified benzyl moieties, achieved continuous high H yield over 1200 mmol g −1 h for an impressive duration 85 hours in flow cell setting, marking it one most efficient non‐pyrolyzed reported date. Theoretical computations alongside situ infrared spectroscopy indicate markedly diminishes adsorption OOH* intermediate, thereby steering towards desired Furthermore, versatility was demonstrated through its application electro‐Fenton reaction, where efficiently rapidly removed aqueous contaminants. This work delineates pioneering approach altering pathway, ultimately paving way development highly effective electrocatalysts.

Language: Английский

---

Functional Regulation of Covalent Organic Frameworks for Photocatalytic Water Splitting

ACS Materials Letters, Journal Year: 2024, Volume and Issue: 6(6), P. 2276 - 2294

Published: May 10, 2024

Solar-driven water splitting into hydrogen and oxygen fuels represents a promising way for clean energy production to achieve carbon-neutral future. The efficiency of photocatalytic strongly relies on the development high-performance catalysts. Noteworthily, covalent organic frameworks (COFs) offer distinctive platform designing photo-to-chemical conversion, benefiting from their tailorable structure, ultrahigh porosity, robust framework, sufficient light absorption, rich active sites. Herein we highlight systematic overview recent research progress using COFs half-reactions overall splitting. With an aim shed understanding structural design COF photocatalysts splitting, various functional strategies are discussed. Finally, major challenges future perspectives proposed with hope achieving ongoing this emerging field.

Language: Английский

---

Interlayer Polymerization to Construct a Fully Conjugated Covalent Organic Framework as a Metal‐Free Oxygen Reduction Reaction Catalyst for Anion Exchange Membrane Fuel Cells

Small, Journal Year: 2024, Volume and Issue: 20(35)

Published: April 28, 2024

Abstract Two‐dimensional (2D) covalent organic frameworks (COFs) have a multilayer skeleton with periodic π‐conjugated molecular array, which can facilitate charge carrier transport within COF layer. However, the lack of an effective transmission pathway between 2D layers greatly limits their applications in electrocatalysis. Herein, by employing side‐chain polymerization strategy to form polythiophene along nanochannels, conjugated bridge is constructed layers. The as‐synthesized fully (PTh‐COF) exhibits high oxygen reduction reaction (ORR) activity narrowed energy band gaps. Correspondingly, PTh‐COF tested as metal‐free cathode catalyst for anion exchange membrane fuel cells (AEMFCs) showed maximum power density 176 mW cm −2 under current 533 mA . functional theory (DFT) calculation reveals that interlayer optimizes electron cloud distribution, therefore enhances ORR performance. This work not only provides new insight into construction framework but also promotes development catalysts.

Language: Английский

---

Advancements and applications of three-dimensional covalent organic frameworks

Chemical Synthesis, Journal Year: 2024, Volume and Issue: 4(2)

Published: May 31, 2024

Covalent organic frameworks (COFs) represent an emerging class of crystalline porous polymers characterized by their pre-designed interconnected structures formed via dynamic covalent bonds. These materials have garnered widespread attention in recent years. While applications two-dimensional (2D) COFs been extensively investigated since 2005, practicality has impeded limited specific surface area and the robust π-π stacking interaction. In contrast, three-dimensional (3D) boast enhanced porosity, larger area, well-exposed functional groups, abundance reaction sites, positioning them at forefront material research. They find extensive diverse fields, including adsorption, separation, catalysis, so on. This featured article provides a comprehensive exploration latest advancements 3D across respective application domains. Additionally, we outline current challenges that must be addressed shed light on promising prospects for utilization COFs.

Language: Английский

---

Coupling electrocatalytic redox-active sites in a three-dimensional bimetalloporphyrin-based covalent organic framework for enhancing carbon dioxide reduction and oxygen evolution

Journal of Materials Chemistry A, Journal Year: 2024, Volume and Issue: 12(16), P. 9478 - 9485

Published: Jan. 1, 2024

The 3D Co/Ni–TPNB-COF couples redox-active sites due to the charge redistribution between Ni( ii )-porphyrin and Co( )-porphyrin, further simultaneously enhances its electrocatalytic carbon dioxide reduction oxygen evolution performances.

Language: Английский

---

Molecular Engineering for Modulating Photocatalytic Hydrogen Evolution of Fully Conjugated 3D Covalent Organic Frameworks

Angewandte Chemie, Journal Year: 2024, Volume and Issue: 136(25)

Published: April 16, 2024

Abstract Covalent organic frameworks (COFs) have recently shown great potential for photocatalytic hydrogen production. Currently almost all reports are focused on two‐dimensional (2D) COFs, while the 3D counterparts rarely explored due to their non‐conjugated derived from sp 3 carbon based tetrahedral building blocks. Here, we rationally designed and synthesized a series of fully conjugated COFs by using saddle‐shaped cyclooctatetrathiophene derivative as block. Through molecular engineering strategies, thoroughly discussed influences key factors including donor‐acceptor structure, hydrophilicity, specific surface areas, well conjugated/non‐conjugated structures evolution properties. The as‐synthesized could generate up 40.36 mmol h −1 g . This is first report intrinsic metal‐free in application. Our work provides insight structure design highly‐efficient photocatalysis, also reveals that semiconducting be useful platform clear energy‐related fields.

Language: Английский

---