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Binding water molecules to polar sites in covalent organic frameworks (COFs) is inevitable, but the corresponding solvent effects in electrocatalytic process have been largely overlooked. Herein, we investigate the solvent effects on COFs for catalyzing the oxygen reduction reaction (ORR). Our designed COFs incorporated different kinds of nitrogen atoms (imine N, pyridine N, and phenazine N), enabling tunable interactions with water molecules. These interactions play a crucial role in modulating electronic states and altering the catalytic centers within the COFs. Among the synthesized COFs, the one with pyridine N atoms exhibits the highest activity, with characterized by a half‐wave potential of 0.78 V and a mass activity of 0.32 A mg−1, which surpass those from other metal‐free COFs. Theoretical calculations further reveal that the enhanced activity can be attributed to the stronger binding ability of *OOH intermediates to the carbon atoms adjacent to the pyridine N sites. This work sheds light on the significance of considering solvent effects on COFs in electrocatalytic systems, providing valuable insights into their design and optimization for improved performance. [ABSTRACT FROM AUTHOR]

Binding water molecules to polar sites in covalent organic frameworks (COFs) is inevitable, but the corresponding solvent effects in electrocatalytic process have been largely overlooked. Herein, we investigate the solvent effects on COFs for catalyzing the oxygen reduction reaction (ORR). Our designed COFs incorporated different kinds of nitrogen atoms (imine N, pyridine N, and phenazine N), enabling tunable interactions with water molecules. These interactions play a crucial role in modulating electronic states and altering the catalytic centers within the COFs. Among the synthesized COFs, the one with pyridine N atoms exhibits the highest activity, with characterized by a half‐wave potential of 0.78 V and a mass activity of 0.32 A mg−1, which surpass those from other metal‐free COFs. Theoretical calculations further reveal that the enhanced activity can be attributed to the stronger binding ability of *OOH intermediates to the carbon atoms adjacent to the pyridine N sites. This work sheds light on the significance of considering solvent effects on COFs in electrocatalytic systems, providing valuable insights into their design and optimization for improved performance. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have been utilized for catalyzing the reduction of carbon dioxide (CO2RR) due to their atomic metal centers and controllable pore channels, which are facilitated by different covalent bonds. However, the exploration of boron‐based linkages in these catalytic COFs has been limited owing to potential instability. Herein, we present the construction of boronic ester‐linked COFs through nucleophilic substitution reactions in order to catalyze the CO2RR. The inclusion of abundant fluorine atoms within the frameworks enhances their hydrophobicity and subsequently improves water tolerance and chemical stability of COFs. The content of boron atoms in the COF linkages was carefully controlled, with COFs featuring a higher density of boron atoms exhibiting increased electronic conductivity, enhanced reductive ability, and stronger binding affinity towards CO2. Consequently, these COFs demonstrate improved activity and selectivity. The optimized COFs achieve the highest activity, achieving a turnover frequency of 1695.3 h−1 and a CO selectivity of 95.0 % at −0.9 V. Operando synchrotron radiation measurements confirm the stability of Co (II) atoms as catalytically active sites. By successfully constructing boronic ester‐linked COFs, we not only address potential instability concerns but also achieve exceptional catalytic performance for CO2RR. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have been utilized for catalyzing the reduction of carbon dioxide (CO2RR) due to their atomic metal centers and controllable pore channels, which are facilitated by different covalent bonds. However, the exploration of boron‐based linkages in these catalytic COFs has been limited owing to potential instability. Herein, we present the construction of boronic ester‐linked COFs through nucleophilic substitution reactions in order to catalyze the CO2RR. The inclusion of abundant fluorine atoms within the frameworks enhances their hydrophobicity and subsequently improves water tolerance and chemical stability of COFs. The content of boron atoms in the COF linkages was carefully controlled, with COFs featuring a higher density of boron atoms exhibiting increased electronic conductivity, enhanced reductive ability, and stronger binding affinity towards CO2. Consequently, these COFs demonstrate improved activity and selectivity. The optimized COFs achieve the highest activity, achieving a turnover frequency of 1695.3 h−1 and a CO selectivity of 95.0 % at −0.9 V. Operando synchrotron radiation measurements confirm the stability of Co (II) atoms as catalytically active sites. By successfully constructing boronic ester‐linked COFs, we not only address potential instability concerns but also achieve exceptional catalytic performance for CO2RR. [ABSTRACT FROM AUTHOR]

Metallic Li is considered the most promising anode material for high‐energy‐density batteries owing to its high theoretical capacity and low electrochemical potential. However, inhomogeneous lithium deposition and uncontrollable growth of lithium dendrites result in low lithium utilization, rapid capacity fading, and poor cycling performance. Herein, two sulfonated covalent organic frameworks (COFs) with different sulfonated group contents are synthesized as the multifunctional interlayers in lithium metal batteries. The sulfonic acid groups in the pore channels can serve as Li‐anchoring sites that effectively coordinate Li ions. These periodically arranged subunits significantly guide uniform Li‐ion flux distribution, guarantee smooth Li deposition, and reduce lithium dendrite formation. Consequently, these characteristics afford an excellent quasi‐solid‐state electrolyte with a high ionic conductivity of 1.9 × 10−3 S cm−1 at room temperature and a superior Li++ transference number of 0.91. A Li/LiFePO4 battery with the COF‐based electrolyte exhibited dendrite‐free Li deposition during the charge process, accompanied by no capacity decay after 100 cycles at 0.1 C. [ABSTRACT FROM AUTHOR]

• The microporous covalent organic framework has been successfully synthesized. • The new COF possess high crystallinity, permanent micropores and excellent stability. • The high-density N and O atoms were decorated on the walls. • The new COF were selected as effective gas uptake scaffolds. Covalent organic frameworks (COFs) are a new class of crystalline porous materials, maintaining porosity, stability, uniform pore channel, and well-designed skeletons. These features trait to be well suited as a platform for effective adsorption and separation of sorbents. Here, we reported microporous and stable COF with high-density N and O atoms that are implanted via the linker and vertex design. The new COF possessed high crystallinity, permanent micropores, excellent thermal and chemical stability, and high-density N and O atoms on the walls. Interestingly, the new COF is able to capture CO 2 of 14.2 wt%, and iodine vapor of 456 wt%. These results evolve structural designs of COFs as effective gas uptake scaffolds. [ABSTRACT FROM AUTHOR]

The catalytic performance for electrocatalytic CO2 reduction reaction (CO2RR) depends on the binding strength of the reactants and intermediates. Covalent organic frameworks (COFs) have been adopted to catalyze CO2RR, and their binding abilities are tuned via constructing donor‐acceptor (DA) systems. However, most DA COFs have single donor and acceptor units, which caused wide‐range but lacking accuracy in modulating the binding strength of intermediates. More elaborate regulation of the interactions with intermediates are necessary and challenge to construct high‐efficiency catalysts. Herein, the three‐component COF with D‐A‐A units was first constructed by introducing electron‐rich diarylamine unit, electron‐deficient benzothiazole and Co‐porphyrin units. Compared with two‐component COFs, the designed COF exhibit elevated electronic conductivity, enhanced reducibility, high efficiency charge transfer, further improving the electrocatalytic CO2RR performance with the faradic efficiency of 97.2 % at −0.8 V and high activity with the partial current density of 27.85 mA cm−2 at −1.0 V which exceed other two‐component COFs. Theoretical calculations demonstrate that catalytic sites in three‐component COF have suitable binding ability of the intermediates, which are benefit for formation of *COOH and desorption of *CO. This work offers valuable insights for the advancement of multi‐component COFs, enabling modulated charge transfer to improve the CO2RR activity. [ABSTRACT FROM AUTHOR]

The catalytic performance for electrocatalytic CO2 reduction reaction (CO2RR) depends on the binding strength of the reactants and intermediates. Covalent organic frameworks (COFs) have been adopted to catalyze CO2RR, and their binding abilities are tuned via constructing donor‐acceptor (DA) systems. However, most DA COFs have single donor and acceptor units, which caused wide‐range but lacking accuracy in modulating the binding strength of intermediates. More elaborate regulation of the interactions with intermediates are necessary and challenge to construct high‐efficiency catalysts. Herein, the three‐component COF with D‐A‐A units was first constructed by introducing electron‐rich diarylamine unit, electron‐deficient benzothiazole and Co‐porphyrin units. Compared with two‐component COFs, the designed COF exhibit elevated electronic conductivity, enhanced reducibility, high efficiency charge transfer, further improving the electrocatalytic CO2RR performance with the faradic efficiency of 97.2 % at −0.8 V and high activity with the partial current density of 27.85 mA cm−2 at −1.0 V which exceed other two‐component COFs. Theoretical calculations demonstrate that catalytic sites in three‐component COF have suitable binding ability of the intermediates, which are benefit for formation of *COOH and desorption of *CO. This work offers valuable insights for the advancement of multi‐component COFs, enabling modulated charge transfer to improve the CO2RR activity. [ABSTRACT FROM AUTHOR]

Two new covalent organic frameworks (COFs) were synthesized from 4,4′,4′′,4′′′‐(pyrene‐1,3,6,8‐tetrayl)tetraaniline and 2,5‐dimethoxyterephthalaldehyde (Py‐DMTA‐COF) or 2′,5′‐dimethoxy‐[1,1′:4′,1′′‐terphenyl]‐4,4′′‐dicarbaldehyde (Py‐DMTPDA‐COF) under solvothermal conditions. These two COFs were further facilely developed as efficient photocatalytic platforms for the synthesis of thiophosphinates. Py‐DMTA‐COF exhibited better photocatalytic activity, broad substrate applicability, and excellent recycling capacity for the preparation of thiophosphinates from P(O)H compounds and thiols compared to Py‐DMTPDA‐COF. This methodology was further extended to the seamless gram‐scale production of target phosphorothioate derivatives. The results demonstrate that COFs can provide a robust platform for developing metal‐free, base‐free, highly efficient, and reusable heterogeneous photocatalysts for organic transformations. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have attracted considerable attention as a facile and versatile design platform for advanced energy storage materials owing to their structural diversity, ordered porous structures, and chemical stability. In this study, a redox‐active COF (TP–OH–COF) that can accommodate 30 Li+ ions is synthesized for potential use as an ultralong cyclable high‐capacity lithium‐ion battery electrode material. The TP–OH–COF is synthesized using triformylpholoroglucinol and 2,5‐diaminohydroquinone dihydrochloride under solvothermal conditions. The accommodation of such exceptional Li+ ion content in the TP–OH–COF is achieved by alternately tethering redox‐active hydroxyl and carbonyl sites on the pore walls. Owing to this unique chemical/structural feature, the TP–OH–COF delivers a high specific capacity of 764.1 mAh g–1, and capacity retention of 63% after 8000 cycles at a fast current density of 5.0 A g–1. [ABSTRACT FROM AUTHOR]

Metal‐free covalent organic frameworks (COFs) have been employed to catalyze the oxygen reduction reaction (ORR). To achieve high activity and selectivity, various building blocks containing heteroatoms and groups linked by imine bonds were used to create catalytic COFs. However, the roles of linkages of COFs in ORR have not been investigated. In this work, the catalytic linkage engineering has been employed to modulate the catalytic behaviors. To create single catalytic sites while avoiding other possible catalytic sites, we synthesized COFs from benzene units linked by various bonds, such as imine, amide, azine, and oxazole bonds. Among these COFs, the oxazole‐linkage in COFs enables to catalyze the ORR with the highest activity, which achieved a half‐wave potential of 0.75 V and a limited current density of 5.5 mA cm−2. Moreover, the oxazole‐linked COF achieved a conversion frequency (TOF) value of 0.0133 S−1, which were 1.9, 1.3, and 7.4‐times that of azine‐, amide‐ and imine‐COFs, respectively. The theoretical calculation showed that the carbon atoms in oxazole linkages facilitated the formation of OOH* and promoted protonation of O* to form the OH*, thus advancing the catalytic activity. This work guides us on which linkages in COFs are suitable for ORR. [ABSTRACT FROM AUTHOR]

Metal‐free covalent organic frameworks (COFs) have been employed to catalyze the oxygen reduction reaction (ORR). To achieve high activity and selectivity, various building blocks containing heteroatoms and groups linked by imine bonds were used to create catalytic COFs. However, the roles of linkages of COFs in ORR have not been investigated. In this work, the catalytic linkage engineering has been employed to modulate the catalytic behaviors. To create single catalytic sites while avoiding other possible catalytic sites, we synthesized COFs from benzene units linked by various bonds, such as imine, amide, azine, and oxazole bonds. Among these COFs, the oxazole‐linkage in COFs enables to catalyze the ORR with the highest activity, which achieved a half‐wave potential of 0.75 V and a limited current density of 5.5 mA cm−2. Moreover, the oxazole‐linked COF achieved a conversion frequency (TOF) value of 0.0133 S−1, which were 1.9, 1.3, and 7.4‐times that of azine‐, amide‐ and imine‐COFs, respectively. The theoretical calculation showed that the carbon atoms in oxazole linkages facilitated the formation of OOH* and promoted protonation of O* to form the OH*, thus advancing the catalytic activity. This work guides us on which linkages in COFs are suitable for ORR. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ladder covalent organic frameworks showed high electrocatalytic performance. • The ladder π-conjugation contributed to electronic conductivity. • The natural phenolic molecule improved CO 2 uptakes and reductive capacity. • The theoretical calculation revealed the phenolic molecule enhance the activity. Covalent organic frameworks (COFs) constructed with metallocyclophane units and organic linkers have found application as electrocatalytic systems. Nevertheless, the majority of linkers within COFs necessitate intricate design and synthesis. Conversely, the potential utilization of natural building blocks in COF construction remains largely unexplored. In this study, we constructed a natural COF (CoPc-EA-COF) by employing a natural phenolic molecule (ellagic acid (EA)) as the linker and Co-hexadecafluorophthalocyanine (CoPc) as blocks. This framework serves as an electrocatalyst for both the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO 2 RR). The incorporation of EA units imparts the CoPc-EA-COF with elevated electronic conductivity, enhanced CO 2 binding affinity, and superior reductive capacity compared to the controlled COF lacking EA units. The CoPc-EA-COF demonstrated enhanced performance in the ORR, as evidenced by a half-wave potential of 0.80 V. Moreover, it showcased elevated activity and selectivity in the CO 2 RR, achieving a maximum CO faradic efficiency of 97.32 % at − 0.8 V, along with turnover frequency (TOF) values reaching 2092 h−1. Theoretical calculations revealed that the presence of EA units facilitated the generation of OOH* and COOH* species, which are pivotal in the rate-determining stages of both ORR and CO 2 RR processes. The contribution of EA units significantly bolstered the overall catalytic activity. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are attractive as metal-free catalysts for the 2e− oxygen reduction reaction (ORR) towing to their tunable skeletons and porosities. However, the specific roles of their properties, such as crystallinity, porosity, dipole moment, and binding ability to reactants, in the catalytic performance are still unknown. In this work, we adopted a linker engineering strategy to reveal the crucial factors in determining the catalytic performance. The properties of the COFs were systematically engineered by altering the substituent groups in the linkers. The optimized Br-COF achieved a maximum selectivity of 86.2%, and a mass activity of 32.0 A g−1, which were 112% and 174% higher than those from unmodified COF, respectively. The experimental and theoretical results revealed that the reductive ability of the COFs exerted the most prominent effect on their catalytic activity and confirmed that the easy formation of an OOH* intermediate contributed to the high activity. [Display omitted] • We have developed seven catalytic COFs with the same topology and porosities, binding ability of O 2 , but possess reductive ability, and thus contributed tailored catalytic activity and selectivity (Br-> Cl-> OH-> OCH 3 -> F-> CH 3 -> H-COF). • The optimized Br-COF exhibited the highest activity and selectivity in the 2e− ORR, which were higher than other reported COFs. • The experimental and theoretical results revealed that the COF with strong reducing ability is easy to form OOH* intermediates, which makes its activity high. [ABSTRACT FROM AUTHOR]

Billions of people are suffering from a shortage of clean water. Covalent organic frameworks (COFs) based membranes show promise in supplying clean water from saline waters due to their designable and controllable porous structures. However, the challenge lies in the rejection of salt ions during the pervaporation process, which is attributed to the relatively large pore size of COFs. Herein, we report the 2D BTCA-TAPB- COF membranes supported on porous ceramics for efficient desalination. The resulting BTCA-TAPB-COF composite membrane consists of nanometer-thick BTCA-TAPB-COF lamellas, which are grown in an oriented manner by suppressing the surface energy. Through pervaporation, the membrane exhibits nearly complete NaCl rejections and high fluxes when processing NaCl solutions at seawater levels, surpassing the reported polymeric membranes. Moreover, the BTCA-TAPB-COF composite membrane exhibits reliable stability for desalination. Effects of desalination methods and charge states of solutes on the exclusion performance are comparatively investigated using BTCA-TAPB-COF composite membrane, which suggest that the surface charge of BTCA-TAPB-COF contributes to high ion rejection via the Donnan exclusion effect. [Display omitted] • Nanometer thick BTCA-TAPB-COF lamellas are obtained by surface energy suppression method. • 2D BTCA-TAPB-COF composite membranes are synthesized by layer-by-layer assembling. • BTCA-TAPB-COF membrane exhibits NaCl rejections >99.9% and high fluxes of ∼40 L m−2 h−1. • The COF composite membrane exhibits reliable stability for desalination. • Surface charge of membrane contributes to high ion rejection via Donnan exclusion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The 1D COFs with alkynal units were constructed for improving OER activity. • The electronic conductivity and charge transfer ability can be modulated in 1D COFs. • The weaker stacking interaction between chains allowed expansion of the interlayer. • The DFT calculation revealed alkynal unites promoted OOH* desorption on Fe sites. Covalent organic frameworks (COFs) have been employed to catalyze the oxygen evolution reaction (OER). However, their catalytic activities have been limited, because their narrow interlayer space hindered the mass transport to the catalytic sites. Herein, we have demonstrated dimensional-controlled interlayer space of COFs for OER. The one dimensional (1D) catalytic COF had weaker stacking interaction between the 1D chains than that from two-dimensional COFs, which allowed for easier expansion of the interlayer distance in catalytic process, leading to enhanced catalytic activity. Moreover, the electronic states were well modulated with extending the length of conjugating units by integrating the alkynal units. The optimized catalyst achieved an overpotential of 225 mV and Tafel slope of 76 mV dec–1 in 1.0 M KOH, outperforming other 2D or 3D COFs. Theoretical calculations demonstrated that the alkynal units facilitated the OOH* desorption on the Fe sites, which further improved the activity. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COF) with periodic porous structures and tunable functionalities are a new class of crystalline polymers connected via strong covalent bonds. Constructing COF materials with high stability and porosity is attracting and essential for COFs' further functional exploration. In this work, two new covalent organic frameworks (TTA‐TMTA‐COF and TTA‐FMTA‐COF) with high surface area, large pore volume, and excellent chemical stability toward harsh conditions are designed and synthesized by integrating the methoxy functional groups into the networks. Both two COFs are further employed for iodine removal since radioactive iodine in nuclear waste has seriously threatened the natural environment and human health. TTA‐TMTA‐COF and TTA‐FMTA‐COF can capture 3.21 and 5.07 g g−1 iodine, respectively. Notably, the iodine capture capacity for iodine of TTA‐FMTA‐COF does not show any decline after being recycled five times. These results demonstrate both COFs possess ultrahigh capacity and excellent recyclability. [ABSTRACT FROM AUTHOR]

As we know, the photoelectric properties of the covalent organic frameworks (COFs) can be properly adjusted by introducing an electron donor–acceptor (D–A) structure. In here, a two-dimensional D–A type Py-BPDAIP-COF with an excellent photoelectric characteristic was prepared in a post-modified method. Significantly, the introducing of very strong electron-withdrawing pyridinium structure dramatically improve inductive and conjugative effects of the electron acceptor unit of Py-BPDAIP-COF. And the electron-rich pyrene skeleton on the knot of the COF was as an electron donor. Then a strong electron push–pull effect between the donor and acceptor units can be transmitted to the COFs backbone, significantly improving the transfer and separation of light-generated electrons. The Py-BPDAIP-COF showed very excellent photocatalytic activity in visible light-induce aerobic hydroxylation, thiocyanation transformation and oxidative C-H functionalization. Therefore, we design and construct a highly efficient olefin-linked D–A type COF photocatalysts via tuning inductive and conjugative effects of pore wall surface. [Display omitted] • A new olefin-linked donor–acceptor pyridinium COFs has been prepared. • Ultra-efficient aerobic hydroxylation reaction could be catalyzed by Py-BPDAIP-COF. • The D-A units in Py-BPDAIP-COF dramatically increase its photocatalytic activity. • The other two organic reactions were also efficiently realized by Py-BPDAIP-COF. [ABSTRACT FROM AUTHOR]

Crystalline covalent organic frameworks (COFs) materials have good performance in photocatalytic conversions due to their excellent photoelectric properties in recent years. here, two new conjugated pyrene-based covalent organic frameworks (COFs), namely PyDF-COF and PyBMT-COF, were prepared through condensation polymerization of 4,4',4'',4'''-(pyrene-1,3,6,8-tetrayl)tetraaniline and 2,5-difluoroterephthalaldehyde or 2,5-bis(methylthio)terephthalaldehyde, respectively. Highly selective aerobic hydroxylation of arylboronic acids can occur smoothly with high yields and a wide range of substrate universality. Compared with PyDF-COF, PyBMT-COF demonstrates a more efficient ability for this aerobic hydroxylation, indicating electron-donating thiomethyl groups of PyBMT-COF are more favorable to enhance distribution of electron cloud than electron-withdrawing fluorine groups of PyDF-COF, which make the PyBMT-COF more easily afford holes and electrons (h+-e-) separation, more effectively absorb visible light, and own narrower bandgap energy, higher photocurrent response, longer fluorescent lifetime and lower electrochemical impedance. [Display omitted] • Two new conjugated pyrene-based covalent organic frameworks have been prepared. • Highly selective aerobic hydroxylation of arylboronic acids proceeded in high yields and a wide substrate scope using PyBMT-COF as a photocatalyst.. • Electron-donating effect of thiomethyl groups in PyBMT-COF dramatically increases the photocatalytic activity compared with PyDF-COF. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are porous crystalline materials that have attracted considerable attention owing to their environmental-friendly photocatalytic characteristics. However, insufficient charge transfer and rapid charge recombination occur in the sunlight-driven photocatalytic performance of most COFs, which greatly impedes their photocatalytic activity. In this study, a donor-acceptor (D-A) COF, DTB-BT-COF, was synthesized using electron-deficient 4,4'-(benzo[c] [1,2,5]thiadiazole-4,7-diyl)dianiline (BT) and electron-rich 1,3-dihydroxy-2,4,6-trialdehyde benzene (DTB). With its D-A structure, DTB-BT-COF exhibited outstanding photocatalytic performance for Cr(VI) reduction, which can be attributed to the integrative effect of the remarkable light absorption ability and more efficient separation of the photogenerated charge carriers. More significantly, DTB-BT-COF has proven to be a highly efficient photocatalyst in the removal of different aqueous contaminants with rhodamine B, methylene blue, or metronidazole as scavengers, which could be attributed to the synergetic effect between photocatalytic oxidation and reduction by individually consuming photogenerated holes and electrons. This study provided a new way to construct highly efficient D-A COFs for the purification of wastewaters containing mixed heavy metal ions and organic pollutants. [Display omitted] • A donor-acceptor (D-A) COF, DTB-BT-COF, was synthesized for the first time. • The benzothiazole-containing D-A structure boosted the carrier separation efficiency. • DTB-BT-COF exhibited outstanding photocatalytic performance for Cr(VI) reduction. • DTB-BT-COF was a difunctional photocatalyst for removing of Cr(VI) and organics. [ABSTRACT FROM AUTHOR]