Bulk COFs and COF nanosheets for electrochemical energy storage and conversion

Chemical Society Reviews, Journal Year: 2020, Volume and Issue: 49(11), P. 3565 - 3604

Published: Jan. 1, 2020

The current advances, structure-property relationship and future perspectives in covalent organic frameworks (COFs) their nanosheets for electrochemical energy storage (EES) conversion (EEC) are summarized.

Language: Английский

---

Photocatalytic Molecular Oxygen Activation by Regulating Excitonic Effects in Covalent Organic Frameworks

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(49), P. 20763 - 20771

Published: Nov. 23, 2020

Excitonic effects caused by Coulomb interactions between electrons and holes play subtle significant roles on photocatalysis, yet have been long ignored. Herein, porphyrinic covalent organic frameworks (COFs, specifically DhaTph-M), in the absence or presence of different metals porphyrin centers, shown as ideal models to regulate excitonic effects. Remarkably, incorporation Zn2+ COF facilitates conversion singlet triplet excitons, whereas Ni2+ introduction promotes dissociation excitons hot carriers under photoexcitation. Accordingly, discriminative behavior DhaTph-Zn DhaTph-Ni enables activation O2 1O2 O2•–, respectively, visible light irradiation, resulting distinctly activity selectivity photocatalytic terpinene oxidation. Benefiting from these results, exhibits excellent O2•–-engaged hydroxylation boronic acid, while possesses superior performance 1O2-mediated selective oxidation sulfides. This work provides in-depth insights into molecular oxygen opens an avenue regulation based COFs.

Language: Английский

---

Regulating Photocatalysis by Spin-State Manipulation of Cobalt in Covalent Organic Frameworks

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(39), P. 16723 - 16731

Published: Sept. 7, 2020

While catalysis is highly dependent on the electronic structure of catalyst, understanding catalytic performance affected by electron spin regulation remains challenging and rare. Herein, we have developed a facile strategy to manipulation cobalt state over covalent organic frameworks (COFs), COF-367-Co, simply changing oxidation Co centered in porphyrin. Density functional theory (DFT) calculations together with experimental results confirm that CoII CoIII are embedded COF-367 S = 1/2 0 ground states, respectively. Remarkably, photocatalytic CO2 reduction indicate COF-367-CoIII exhibits favorable activity significantly enhanced selectivity HCOOH, accordingly much reduced CO CH4, sharp contrast COF-367-CoII. The highlight spin-state transition greatly regulates performance. Theoretical further disclose presence COF-367-Co preferable formation HCOOH but detrimental its conversion, which clearly accounts for distinctly different photocatalysis To best our knowledge, this first report regulating COFs.

Language: Английский

---

Reconstructed covalent organic frameworks

Nature, Journal Year: 2022, Volume and Issue: 604(7904), P. 72 - 79

Published: April 6, 2022

Abstract Covalent organic frameworks (COFs) are distinguished from other polymers by their crystallinity 1–3 , but it remains challenging to obtain robust, highly crystalline COFs because the framework-forming reactions poorly reversible 4,5 . More chemistry can improve 6–9 this typically yields with poor physicochemical stability and limited application scope 5 Here we report a general scalable protocol prepare imine COFs, based on an unexpected framework reconstruction. In contrast standard approaches in which monomers initially randomly aligned, our method involves pre-organization of using removable covalent tether, followed confined polymerization. This reconstruction route produces reconstructed greatly enhanced much higher porosity means simple vacuum-free synthetic procedure. The increased improves charge carrier transport, leading sacrificial photocatalytic hydrogen evolution rates up 27.98 mmol h −1 g nanoconfinement-assisted strategy is step towards programming function materials through atomistic structural control.

Language: Английский

---

Design Rules of Hydrogen-Bonded Organic Frameworks with High Chemical and Thermal Stabilities

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(24), P. 10663 - 10687

Published: June 8, 2022

Hydrogen-bonded organic frameworks (HOFs), self-assembled from strategically pre-designed molecular tectons with complementary hydrogen-bonding patterns, are rapidly evolving into a novel and important class of porous materials. In addition to their common features shared other functionalized materials constructed modular building blocks, the intrinsically flexible reversible H-bonding connections endow HOFs straightforward purification procedures, high crystallinity, solution processability, recyclability. These unique advantages have attracted considerable attention across broad range fields, including gas adsorption separation, catalysis, chemical sensing, electrical optical However, relatively weak interactions within can potentially limit stability potential use in further applications. To that end, this Perspective highlights recent advances development chemically thermally robust HOF systematically discusses relevant design rules synthesis strategies access highly stable HOFs.

Language: Английский

---

A nitrogen-rich covalent organic framework for simultaneous dynamic capture of iodine and methyl iodide

Chem, Journal Year: 2020, Volume and Issue: 7(3), P. 699 - 714

Published: Dec. 18, 2020

Language: Английский

---

Confining and Highly Dispersing Single Polyoxometalate Clusters in Covalent Organic Frameworks by Covalent Linkages for CO₂ Photoreduction

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(4), P. 1861 - 1871

Published: Jan. 20, 2022

Single clusters have attracted extensive research interest in the field of catalysis. However, achieving a highly uniform dispersion single-cluster catalyst is challenging. In this work, for first time, we present versatile strategy uniformly dispersed polyoxometalates (POMs) covalent organic frameworks (COFs) through confining POM cluster into regular nanopores COF by linkage. These COF-POM composites combine properties light absorption, electron transfer, and suitable catalytic active sites; as result, they exhibit outstanding activity artificial photosynthesis: that is, CO2 photoreduction with H2O donor. Among them, TCOF-MnMo6 achieved highest CO yield (37.25 μmol g-1 h-1 ca. 100% selectivity) gas-solid reaction system. Furthermore, mechanism study based on density functional theory (DFT) calculations demonstrated photoinduced transfer (PET) process occurs from to POM, then reduction oxidation occur COF, respectively. This work developed method single which also shows potential using materials photocatalysis.

Language: Английский

---

MOF-in-COF molecular sieving membrane for selective hydrogen separation

Nature Communications, Journal Year: 2021, Volume and Issue: 12(1)

Published: Jan. 4, 2021

Abstract Covalent organic frameworks (COFs) are promising materials for advanced molecular-separation membranes, but their wide nanometer-sized pores prevent selective gas separation through molecular sieving. Herein, we propose a MOF-in-COF concept the confined growth of metal-organic framework (MOFs) inside supported COF layer to prepare membranes. These membranes feature unique micro/nanopore network, presumably due formation MOFs as pearl string-like chain unit cells in 1D channel 2D COFs. The exhibit an excellent hydrogen permeance (>3000 GPU) together with significant enhancement selectivity over other gases. superior performance H 2 /CO and /CH 4 surpasses Robeson upper bounds, benefiting from synergy combining precise size sieving fast transport channels. synthesis different combinations COFs robust demonstrates versatility our design strategy.

Language: Английский

---

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

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Feb. 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.

Language: Английский

---

Two-Dimensional Covalent Organic Frameworks with Cobalt(II)-Phthalocyanine Sites for Efficient Electrocatalytic Carbon Dioxide Reduction

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(18), P. 7104 - 7113

Published: May 3, 2021

The rapid development in synthesis methodology and applications for covalent organic frameworks (COFs) has been witnessed recent years. However, the of highly stable functional COFs still remains a great challenge. Herein two-dimensional polyimide-linked phthalocyanine (denoted as CoPc-PI-COF-1 CoPc-PI-COF-2) have devised prepared through solvothermal reaction tetraanhydrides 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato cobalt(II) with 1,4-phenylenediamine 4,4′-biphenyldiamine, respectively. resultant CoPc-PI-COFs four-connected sql net exhibit AA stacking configurations according to powder X-ray diffraction studies, showing permanent porosity, thermal stability above 300 °C, excellent resistance 12 M HCl aqueous solution 20 days. Current–voltage curves reveal conductivity CoPc-PI-COF-2 value 3.7 × 10–3 1.6 S m–1, Due same Co(II) electroactive sites together similar porosity CO2 adsorption capacity CoPc-PI-COFs, cathodes made up carbon black display CO2-to-CO Faradaic efficiency 87–97% at applied potentials between −0.60 −0.90 V (vs RHE) 0.5 KHCO3 solution. comparison CoPc-PI-COF-2&carbon electrode, counterpart provides larger current density (jCO) −21.2 mA cm–2 associated its higher conductivity. This cathode also high turnover number frequency, amounting 277 000 2.2 s–1 −0.70 during 40 h measurement. present result clearly discloses potential 2D porous crystalline solids electrocatalysis.

Language: Английский

---