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Covalent organic frameworks (COFs) are nanoporous crystalline polymers with densely conjugated structures. This work discovers that imine-linked COFs exhibit remarkable photodegradation efficiency to azo dyes dissolved in water. Visible light generates different types of radicals from COFs, and superoxide radicals break N N bonds in dye molecules, resulting in 100% degradation of azo dyes within 1 h. In contrast, these dyes cannot be degraded by conventionally used photocatalysts, for example, TiO2. Importantly, the COF photocatalysts can be recovered from the dye solutions and re-used to degrade azo dyes for multiple times without loss of degradation efficiency. This work provides an efficient strategy to degrade synthetic dyes, and we expect that COFs with designable structures may use as new photocatalysts for other important applications.

Derivatization of 2D materials for bioapplications is at the forefront of nanomaterials research nowadays. Facile synthesis of the biografted 2D derivatives and insight into the conformation of the conjugated biomolecules are two pillars, promoting advances in the field of biosensing, drug delivery and regeneration techniques. This work is devoted to the synthesis and conjugation of carboxylated graphene by aptamers followed by theoretical analysis of their conformation in the immobilized state. Employing the developed method, the hole-matrixed graphene with up to 11.1 at.% reactive carboxyl groups was synthesized and thoroughly examined via core-level spectroscopy and time-resolved methods. The mechanism of the performed carboxylation with conversion of graphene oxide into carboxylated graphene is proposed, unveiling commonly disregarded impact of ether-like components to the fingerprints of the carboxyl groups. We show successful covalent immobilization of the AO-01 aptamer against Hepatitis B protein on the synthesized C-xy graphene and for the first time reveal its conformation both in free and immobilized forms via a combination of density functional theory (DFT) calculations and molecular dynamic (MD) modeling. Taken together, these results advance the application of graphene derivatives grafted with the biomolecules in the field of biosensing.

Aggregation-induced emission (AIE) based luminescent materials are generating intensive interest due to their unique fluorescence in the aggregation state. Herein we report a strategy of dynamic covalent chemistry (DCC) controlled AIE luminogens for the regulation of multicolor emission in reversible covalent polymer networks. Tetraphenylethene derived ring-chain tautomers were prepared, and the emission was readily controlled through multimode, such as changing the solvent, adding the base, and dynamic covalent reactions with amines. Moreover, the construction of dynamic covalent cross-linked luminescent hydrogels with tunable fluorescent, self-healing, and mechanical properties, was realized. The combination of AIE and aggregation-caused quenching (ACQ) fluorophores in the polymer network further enabled the realization of a multicolor modulator, including white emission, in both solution and gel states. The strategies and results presented should find utility in dynamic assemblies, polymer networks, chemical sensing, and responsive materials.

The urgent need for immediate personal protection against chemical warfare agents (CWAs) spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices. Herein, as a new concept for CWA decontamination catalyst design, sub-nanoscale, catalytically active zirconium-oxo molecular clusters are covalently integrated in flexible polymer network as crosslinkers for the full exposure of catalytic sites as well as robust framework structures. The obtained membrane catalysts exhibit high swelling ratio with aqueous content as 84 wt% and therefore, demonstrate quasi-homogeneous catalytic activity toward the rapid hydrolysis of both CWA, soman (GD) (t1/2 = 5.0 min) and CWA simulant, methyl paraoxon (DMNP) (t1/2 = 8.9 min). Meanwhile, due to the covalent nature of cross-linkages and the high flexibility of polymer strands, the membranes possess promising mechanical strength and toughness that can stand the impact of high gas pressures and show high permeation for both CO2 and O2, enabling their extended applications in the field of collective/personal protective materials with body comfort.

Covalent organic frameworks (COFs), as a novel class of functional polymers, exhibit versatile applications due to their crystalline porous structures and conjugated skeletons. However, synthesis of COFs with high crystallinity still faces great challenges, especially for scale-up preparation. Herein we report a two-step solvothermal process to improve crystallinity of COFs. The first step focuses on polycondensation of monomers with no need for optimizing crystallization conditions. In the second step, appropriate solvothermal conditions are used to facilitate crystallization of the COFs through defects correction and structural repairing. Furthermore, this strategy could also be applicable to scale-up synthesis of high quality COFs, which lays a foundation for their practical applications.

The nonradiative recombination of charge carriers at the hole transport layer (HTL)/perovskite interface generally induces remarkable performance loss of the inverted two-dimensional perovskite solar cells (2D PSCs). Herein, a cross-linkable small molecule of 2-mercaptoimidazole (2-MI) was introduced into the nickel oxide (NiOx)/2D perovskite interface. Experiments have confirmed the formation of Ni-N covalent bond by N atom in the 2-MI and Ni in the NiOx and the coordinating between S atom of 2-MI and under-coordinated Pb2+ near to the NiOx/perovskite interface, which contributes to creating a cross-linking between NiOx/perovskite interface to restrain charge carrier recombination and enhance the extraction of hole carriers at the interface. Besides, the 2-MI modification layer is also beneficial for promoting the crystallinity of 2D perovskite. Consequently, the inverted 2D PSCs with 2-MI modification achieved the best power conversion efficiency of 15%. This paves a route to acquire highly efficient 2D PSCs by constructing a cross-linking at the NiOx HTL/2D perovskite interface.

Though Olefin-linked covalent organic frameworks (oCOFs) possess excellent π-electron delocalization, the barely reversible olefin linkage brings challenges for oCOFs’ synthesis and functionalization. Here, we synthesize new oCOFs with tertiary amine knots which have twisted configuration and electron-donating nature. Investigation into the structural variation and photoelectric performance shows that the twisted configuration of oCOF-TFPA could favor to the intramolecular charge transfer process and reduce the possibility of aggregation-caused quenching. Photoelectrical measurements and electric band structure calculation both verify the superiority of this oCOFs’ structure in photoelectric sensing.

High discharged energy density and excellent flexible properties in dielectric materials are significantly sought to meet the rapid advancements in the electronics industry. In this study, covalent bonds are constructed between poly(vinylidene fluoride-chlorotrifluoroethylene), which contains olefinic bonds, and thiol-modified BaTiO3 at the interface before the nanocomposite films are fabricated. The presence of the covalent bonds is proved to promote the dispersibility of the modified BaTiO3 and enhance the interfacial adhesion between the modified BaTiO3 and the polymer, followed by a remarkably positive effect in suppressing the dielectric loss (tanδ) and increasing the breakdown strength (Eb) of the nanocomposite films. In addition, the cross-linking treatment in the preparation process is found to be favourable for improving the mechanical properties of the nanocomposite films, which benefits the enhancement of Eb. Furthermore, at 400% elongation, the stretched nanocomposite film doped with 5 vol% modified BaTiO3 exhibits an Eb 15.6% greater than that of the unstretched film, and the discharged energy density reaches 11.4 J/cm3 with a high discharge energy efficiency of 84.5%. This study provides a novel strategy for preparing flexible nanocomposites with powerful interfacial adhesion at high filler content to achieve high discharged energy density.

Interface wettability is a vital role in directly impacting the electrical contact characteristics of oxides/Cu-based composites under arc erosion. Exploring its influence mechanism, especially at atomic/electronic scales, is significant but challenging for the rational design of oxides/Cu contacts. Here, we designed Zn2SnO4/Cu electrical contacts aiming to solve the poor wettability of SnO2/Cu composites. It was found that Zn2SnO4 could remarkably improve the arc resistance of Cu-based electrical contacts, which was benefited by the excellent interface wettability of Zn2SnO4/Cu. The characterization of eroded surface indicated that Zn2SnO4 particles distributed uniformly on the contact surface, leading to stable electrical contact characteristic. Nevertheless, SnO2 considerably deteriorated the arc resistance of SnO2/Cu composite by agglomerating on the surface. The effect mechanism of wettability on arc resistance was investigated through density function theory (DFT) study. It revealed that strong polar covalent bonds across the Zn2SnO4/Cu interface contributed to improving the interfacial adhesion strength/wettability and thus significantly enhanced the arc resistance. For binary SnO2/Cu interface, ionic bonds resulted in weak interface adhesion, giving rise to deterioration of electrical contact characteristic. This work discloses the bonding mechanism of oxide/Cu interfaces and paves an avenue for the rational design of ternary oxide/Cu-based electrical contact materials.

Fe3O4-based materials are widely used for magnetic separation from wastewater. However, they often suffer from Fe-leaching behavior under acidic conditions, decreasing their activity and limiting sustainable practical applications. In this study, covalent organic frameworks (COFs) were used as the shell to protect the Fe3O4 core, and the Fe3O4@COF core-shell composites were synthesized for As(III) removal from acid wastewater. The imine-linked COFs can in situ grow on the surface of the Fe3O4 core layer by layer with [COFs/Fe3O4]mol ratio of up to 2:1. The Fe-leaching behavior was weakened over a wide pH range of 1-13. Moreover, such composites keep their magnetic characteristic, making them favorable for nanomaterial separation. As(III) batch adsorption experiments results indicated that, when COFs are used as the shell for the Fe3O4 core, a balance between As(III) removal efficiencies and the thickness of the COF shell exists. Higher As(III) removal efficiencies are obtained when the [COFs/Fe3O4]mol ratios were

Novel bioactive injectable composites based on biopolymeric hydrogels reinforced with insulin-functionalized silica particles were synthesized. The insulin (INS) was immobilized on the surface of amine-modified silica particles employing covalent attachment by EDC/NHS chemistry and via electrostatic interaction. The resulting formulations were examined for the morphology (SEM), chemical composition (FTIR, XPS) as well as protein content. To facilitate the injectability and support the bone regeneration, developed particles were dispersed in biopolymeric sol composed of collagen, chitosan and lysine-modified hyaluronic acid and crosslinked with genipin. By means of rheological study, the sol-gel in situ transition of obtained systems was verified. It was found in vitro study that MG-63 cells cultured on the developed composites exhibit significantly higher alkaline phosphatase (ALP) activity, compared to the pristine hydrogel. Furthermore, the biomineralization ability in the simulated body fluid (SBF) model was also demonstrated. Our findings suggest that proposed herein novel hydrogel-based composites might be the promising formulation for regeneration of bone defects, especially as a less-cost effective support/alternative for BMP-2 systems.

Carbon dots (CDs) have attracted more interest in tumor theranostics, but they suffer from the rapid renal clearance due to small size and high hydrophilicity. To solve such problems, hydrophobic pH-triggered carbon dot-drug conjugate (CDs-Hy-DOX) with high doxorubicin (DOX) content of 48.23% were designed by covalent conjugation of DOX onto the CDs via acid-labile linkage with hydrazine (Hy) as bridge. Then the fluorescent traceable hybrid prodrug nanoparticles were fabricated via co-self-assembly with the CDs-Hy-DOX as pH-sensitive prodrug and a pH/reduction dual-triggered degradable hyperbranched polymer PEG-PO-Cy as polyethylene glycol (PEG)-based surfactant, as well as gatekeeper for pH/reduction dual-triggered DOX release. The hybrid prodrug nanoparticles with hydrodynamic diameter of 220 nm and DOX content of 22.99% were obtained with the optimized co-self-assembling condition. They could release 68.98% of DOX in the simulated tumor microenvironment within 3 days in a sustained release mode, with a premature drug leakage of 7.58%. After the acid-triggered DOX release from the CDs-Hy-DOX, which was accelerated by the pH/reduction dual-triggered degradation of the hyperbranched polymer, the strong fluorescence of CDs-Hy was recovered, demonstrating the promising potential in future tumor nanotheranostics.

Morphology-controlled electrocatalysts with the ability of CO2 adsorption/activation, mass transfer, high stability and porosity are much desired in electrochemical CO2 reduction reaction (CO2RR). Here, three kinds of multi-dimensional nanostructures (i.e., hollow sphere, nanosheets and nanofibers) have been successfully produced through the modulation of porphyrin-based covalent organic frameworks (COFs) with various modulators. The obtained nanostructures with high-stability, large surface-area, and single metal sites enable efficient CO2RR into CH4. Notably, they all exhibit higher FECH4 (hollow sphere, 68.2%; nanosheet, 64.2% and nanofiber, 71.0%, -0.9 V) than COF-366-Cu (43.0%, -0.9 V) after morphology control. Noteworthy, the FECH4 of COF-366-Cu (HS) keeps higher than 52.4% over a wide potential range from -0.9 V to -1.1 V and the achieved FECH4+C2H4 (82.8%, -0.9 V) is superior to most of reported COFs and copper-based electrocatalysts. This work paves a new way in the exploration of COF-based multi-dimensional nanostructures applicable in efficient CO2RR to CH4.

N6-methyl adenosine (m6A) is an eminent epigenetic mark in mRNAs that affects a broad range of biological functions in diverse species. However, the chemically inert methyl group prevents a direct labeling of this modification for subsequent detection and sequencing. Therefore, most current approaches for the labeling of m6A still have limitations of relying on the utilization of corresponding methyltransferases, which resulted in the lacking of efficiency. Here we present an approach which selectively alkylated the N6-formyl adenosine (f6A), the key intermediate during chemical oxidation of m6A, with an alkyne functionality that can be further labeled with click reactions. This covalent labeling approach will be able to facilitate in the affinity purification, detection and genome-wide profiling studies.

Energetic electrons have recently evolved as powerful tool for crosslinking bio-derived hydrogels without the need for adding potentially hazardous reagents. Application of this approach allows for synthesis of biomimetic collagen-derived networks of highly tunable properties and functionalization. Yet, the underlying reaction kinetics it still not sufficiently established at this point. While hydroxyl radicals are generated by energetic electron-induced hydrolysis of water and play a key role in introducing covalent bonds between network fibers, a detailed mechanistic understanding would significantly increase applicability. We present a comprehensive analysis of central aspects of the reactivity between the hydroxyl radical (•OH) and collagen, elastin, glycine (Gly) and L-lysine (Lys). Pulse radiolysis (PR), solid state nuclear magnetic resonance (NMR), ultraviolet-visible absorption spectroscopy (UV/VIS) and electron spray ionization mass spectrometry (ESI-MS) shine light on distinct features of the crosslinking process. These highlight retained protein backbone integrity in collagen and elastin whilst Lys's ability to form several imine bonded Lys-Lys species suggests striking similarities to crosslinking via lysyloxidase catalysis in vivo. Thus, energetic electron based crosslinking opens the venue for customized hybrid gels of outstanding biomimicry and –compatibility. Statement of significance Energetic electron beam treatment constitutes a highly attractive approach to establish chemical bonds between (bio) molecules. Although a convincing number of publications showed the versatility regarding crosslinking of bioderived hydrogels, insights into the underlying chemistry are still unestablished at this point. The present work unravels the mechanistics of energetic electron induced processes in collagen and elastin hydrogels as well as several abundant amino acids in aqueous solution. As key finding we demonstrate, that i) the connection between polymer chains is dominated by amino acid side chain interaction and ii) two single L-lysine molecules form an imine bond between the terminal amino group of one molecule and the delta carbon of the second molecule. We also consider the formation of H-bonds as a second crosslinking pathway. These findings open up for advanced, optionally spatially resolved biomaterials design.

Summary Although advances in coating technologies have allowed us to match—or even exceed—the lubricity of Nature’s low-friction surfaces, the performance of synthetic materials inevitably diminishes over time as the surfaces are worn and damaged by irreversible breakage of covalent bonds. Synthetic systems lack the bespoke repair mechanisms that replenish hydration lubrication surfaces in Nature. Here, we demonstrate dynamic repair of low-friction surfaces prepared through a surface-selective self-assembly strategy. Monolayers of lubricating polymers associate with functionalized surfaces through strong and specific host–guest interactions, leading to hydration lubrication surfaces with low coefficients of friction (0.024–0.028). Following friction-induced dissociation of the polymers, the polymer-to-surface interaction is restored by the reformation of host–guest complexes, thus repairing the monolayer, renewing the lubricity, and reducing the effects of wear. Such dynamically restored low-friction materials will be an essential tool in decreasing global energy use—a fifth of which is expended overcoming friction.

Controlling the spatial confinement effect and highly dispersed Pd nanoparticles (NPs) can help to improve applicability in catalysis, energy conversion, and separation. However, the nonspatial confinement effect, agglomeration of Pd NPs of catalyst and harsh reaction conditions have become the urgent problems to be solved in Suzuki-Miyaura cross-coupling reaction. Herein, we report the first application of a new MOFs@COFs by using core with metal organic frameworks (MOFs) NH2-MIL-101(Fe) and shell with covalent organic frameworks (COFs) for loading Pd NPs. The quickly formation of a transition state, the highly dispersed Pd NPs and the advancedly spatial confinement effect were achieved by coupling Fe base synergistic active components, electron-oriented anchoring with controlling pore scale, respectively. Most notably, as a proof-of-concept application, the high catalytic activity of NH2-MIL-101(Fe)@Pd@COFs(3 + 3) in catalysis is elucidated for Suzuki-Miyaura coupling reaction by the broad scope of the reactants and the preeminent yields of the products, together with excellent stability and recoverability. With this strategy, the mechanism of Suzuki-Miyaura coupling reaction was verified by examining the catalytic activity. We hope that our approach can further facilitate the study of the design and use of functional MOFs@Pd@COFs materials.

Chiral covalent organic frameworks (CCOFs) featuring chirality, stability, and good porosity have attracted a considerable amount of attention due to their important applications, such as asymmetric catalysis, chiral separation, and chiral recognition. In this study, a β-cyclodextrin (β-CD) covalent organic framework (β-CD-COF) diluted with polysiloxane OV-1701 was explored as a novel chiral stationary phase (CSP) for gas chromatography (GC) separation of racemates. The β-CD-COF coated capillary column had excellent selectivity, not only for the separation of linear alkanes, linear alcohols, fatty acid methyl esters mixture, the Grob mixture and positional isomers, but also for the resolution of chiral compounds, including chiral alcohols, aldehydes, ethers, and amino acid derivatives. In addition, the β-CD-COF-coated capillary column presented good repeatability and reproducibility. This work indicated the great potential of the CCOFs coated capillary column for the chromatographic separation of enantiomers.

A mixed drug self-delivery system (DSDS) with high drug content (>50%) was developed to regulate pH-triggered drug release, based on two doxorubicin (DOX)-DOX dimmers: D-DOXADH and D-DOXcar conjugated with acid-labile dynamic covalent bonds (hydrazone and carbamate, respectively) and stabilized with PEGylated D-DOXADH (D-DOXADH-PEG). Owing to the different stability of the dynamic covalent bonds in the two dimers and the noncovalent interaction between them, pH-triggered drug release could be easily regulated by adjusting the feeding ratios of the two DOX-DOX dimers in the mixed DSDS. Similar in vitro cellular toxicity was achieved with the mixed DSDS nanoparticles prepared with different feeding ratios, that had a similar DOX content and diameter but different drug releasing rates. The MTT assays revealed that a high anti-tumor efficacy could be achieved with the slow-release mixed DSDS nanoparticles.

It is a major challenge to combine the advantages of two kinds of two-dimensional materials to construct a heterojunction and achieve efficient photocatalytic antifouling. In this work, we covalently connected two materials MXenes and covalent organic frameworks (COFs) through the Schiff base reaction and anchored Ag nanoparticles (NPs) to prepare a Ti3C2/TpPa-1/Ag composite material with high efficiency bactericidal properties. The covalent bonding between MXene and COF greatly improved the stability of the material. Ti3C2/TpPa-1/Ag composite showed an excellent antibacterial property against S. aureus and P. aeruginosa. The fluorescence spectra of Ti3C2/TpPa-1/Ag proved that the electron transfer channels formed between the ternary materials could greatly improve the efficiency of carrier separation and prolong the life of photogenerated carriers. Density functional theory calculations showed that the synergistic catalytic effect of Ag and Ti3C2 could greatly reduce the work function along the interface, and the built-in electric field between the layers drive carrier fast migration, which effectively improve the catalytic performance.

In this work, a series of novel proton-gradient-transfer acid complexes (PGTACs) were developed. Their physicochemical properties, including thermal stability, melting point, and Hammett acidity, were measured. The effects of catalyst loading, reaction temperature, and substrate expansion on the catalytic performance were systematically studied. It is found that the combination of bidentate N-heterocycle and H2SO4 (1:2 M ratio) could form simultaneously N–H covalent bond and N⋯H hydrogen bond, which makes the PGTACs excellent catalysts integrate the advantages of strong acids (high catalytic activity) and ionic liquids (phase separation) in the esterification reaction. Moreover, these PGTACs can be reused by convenient phase separation without obvious diminution of catalytic activity. It is concluded that these PGTACs are potential alternative candidates for esterification reaction in the process of industrial catalysis.

The development of functional covalent organic frameworks (COFs) with specific properties is an emerging research field. In the current work, COF-SQ-Ph was synthesized through the aza-Diels-Alder reaction between phenylacetylene and the matrix COF-SQ (triazine-based COF) generated from the organic monomers 2, 4, 6-tris(4-aminophenyl)-1, 3, 5-triazine and 2, 5-dimethoxyterephthalaldehyde in flask. The functionalized COF-SQ-Ph with an extended π-conjugated structure and enhanced structural stability was used as the sulfur loading recipient to prepare sulfur cathodes for lithium-sulfur batteries. Sulfur-impregnated COF-SQ-Ph marked as COF-SQ-Ph-S displayed better cycling stability with a specific capacity of 618 mA h g−1 after 150 cycles due to the lithiophilic interaction between lithium polysulfides and nitrogen atoms from quinoline and triazine moieties in COF-SQ-Ph-S. The functionalization of triazine-based COFs through a cycloaddition reaction in flask could promote the large-scale preparation of tailored COFs and the post-synthesis modification of COF-SQ.

The disulfide bond is a covalent bond formed between the sulfur atoms of two cysteine residues in proteins. Our understanding of the role of these ubiquitous bonds in protein function has changed dramatically over the past decade. Initially thought to be fully formed and inert in the native protein, we know now that both these assumptions are incorrect for many proteins. Here, we review recent evidence for production and function of multiple partially disulfide-bonded forms of plasma fibrinogen and platelet αIIbβ3 integrin. The disulfide bonds are not cleaved in these mature proteins but rather a significant fraction of the bonds never form during maturation of the protein. The resulting different covalent states influence the functioning of the protein. These findings change our concept of the native, functional protein.

As one of the specific biomarkers of anthrax, timely, sensitive and accurate detection of 2,6-dipicolinic acid (DPA) plays an important role in preventing biological weapons attacks and disease outbreaks. Here, multiemission Eu3+/covalent- organic framework (COFDTA-TFP) and Tb3+/COFDTA-TFP were constructed by the coordination between Eu3+ or Tb3+ with fluorescent COFDTA-TFP which was prepared by amine-aldehyde dehydration condensation between 2,5-diaminoterephthalic acid and 2,4,6-triformylphloroglucinol for the first time. The Eu3+/COFDTA-TFP and Tb3+/COFDTA-TFP can emit non-overlapping fluorescence of COFDTA-TFP and Eu3+ or Tb3+, which was used to ratiometric detection of DPA. Due to the strong coordination between the nitrogen atoms in the pyridine ring and the oxygen atoms in the carboxyl group of DPA with Eu3+ or Tb3+, DPA replaced coordinated H2O to sensitize fluorescence of Eu3+ or Tb3+ by “antenna” effect but fluorescence of COFDTA-TFP with two-dimensional lamellar structure was kept constant as a reference. The linear range and detection limit of ratiometric fluorescence sensor based on Eu3+/COFDTA-TFP for detection of DPA are 0.01–12 µM and 4.2 nM, respectively. The linear range and detection limit of ratiometric fluorescence sensor based on Tb3+/COFDTA-TFP for detection of DPA are 0.01–9.0 µM and 2.9 nM, respectively.

Covalent triazine-based frameworks (CTFs) have been emerged as a promising organic material for photocatalytic water splitting. However, all of the CTFs only are in the form of AA stacking model to participate in water splitting. Herein, two CTF-1 isomers with different stacking models (eclipsed AA, staggered AB) were obtained by modulating the reaction temperature. Interestingly, experimental and theoretical calculations showed that the crystalline AB stacking CTF-1 possessed a much higher activity for photochemical hydrogen evolution (362 μmol g−1 h−1) than AA stacking CTF-1 (70 µmol h−1 g−1) for the first time. The outstanding photochemical performance could be attributed to its distinct structural feature that allows more N atoms with higher electron-withdrawing property to be involved in the water reduction reaction. Notably, as a cathode material for PEC water reduction, AB stacking CTF-1 also demonstrated an excellent saturated photocurrent density up to 77 µA cm−2 at 0 V vs. RHE, which was superior to the AA stacking CTF-1 (47 µA cm−2). Furthermore, the correlation between stacking models and photocatalytic H2 evolution of CTF-1 were investigated. This study thus paves the path for designing optimal photocatalyst and extending the novel applications of CTF-based materials.

Covalent organic frameworks (COFs) have been recognized as a new type of promising visible-light-driven photocatalysts for H2 evolution, while it still is a key point to facilitate the separation and transfer of photoinduced charges for further enhancing their activities. In this work, we fabricated a new type of ternary Pt/rGO/COF photocatalysts with Pt cocatalyst precisely anchored on rGO serving as electron collector for largely enhanced H2 evolution. A series of ternary hybrid materials were obtained via one-pot photoreduction of Pt4+ and GO under visible-light irradiation in a solution the same as photocatalytic H2 evolution reaction and simultaneous self-assembling of rGO/COF heterostructure. No need isolation, the synthetic system could be further used for photocatalytic H2 evolution reaction and the results show the H2 evolution rate of Pt/rGO(20%)/TpPa-1-COF hybrid material is 19.59 mmol·g−1·h−1, 6.51 times higher than that of Pt/TpPa-1-COF. The essential role of the exclusively distributed Pt nanoparticles on rGO to the high H2 evolution activity was confirmed by various comparisons of activity for the samples with diverse Pt distribution.

Covalent organic frameworks (COFs) feature covalent bond-supported crystallinity along with high encapsulating and mass transport abilities. Together with the ease of chemical addition of electroactive moieties, these properties have recently raised interest in this class of material in organic electronics. In this review, we systematically summarize the utilization of advantageous characteristics of COFs to fulfill different functions in electronic processes, resulting in various applications. Broadly, COFs have been successfully implemented as conductive or semiconductive components for electronic devices, such as organic photodetector and photovoltaics, organic transistors, organic light-emitting devices, and organic sensor and memory devices. Simultaneously, general tactics to provide electroactive functionalities are discussed, providing open considerations and inspiration for future electronic design.

As the desired sulfur host of lithium-sulfur battery, the strong polarity and fast electron migration capability are indispensable for achieving effective adsorption and conversion of lithium polysulfides (LiPSs), that is, restricting the shuttle effect. Herein a porous microdisk Ti4O7/TiN/C heterojunction with strong polar N-Ti-O covalent bonds is precisely constructed. Compared with O-Ti-O or N-Ti-N bond in single Ti4O7 or TiN, the N-Ti-O bond with stronger polarity could adsorb and bond with S and Li atoms in LiPSs, which is beneficial for LiPSs adsorption. Beside, the Ti4O7/TiN heterostructure favors the electron transfer, which could promote the conversion of LiPSs. The design strategy is to construct abundant polar N-Ti-O bonds at Ti4O7/TiN heterogeneous interface that would realize the associative process of LiPSs adsorption, trapping, and conversion, thereby restraining the shuttle effect efficiently. In the current study, as the host of the sulfur cathode, the porous microdisk TiN/Ti4O7/C heterojunction exhibits a high specific capacity of 1204.5 mAh g−1 at 0.2 C, and a high specific capacity of 616.5 mAh g−1 at an ultrahigh current density of 4 C. In addition, 86.4% and 116.9% capacity are retained over 1000 cycles at 1 C and 2 C, respectively. This strategy provides an insight into developing lithium-sulfur battery with extraordinary performance, and opens promising routes to design the next-generation electrochemical energy storage devices.

Ti-silicates activate H2O2 to form Ti-hydroperoxo and Ti-peroxo intermediates that can react with alkenes to form epoxide products. Comparisons of kinetics for 1-octene epoxidation with H2O2 on Ti-BEA and Ti-MFI catalysts with different hydrophilicities in methanol (CH3OH) or acetonitrile (CH3CN) solvents show the significance of the solvent for stabilizing catalytically-relevant species and the complex interdependencies between solvent, catalyst topology, and hydrophilicity. Epoxidation turnover rates are higher in CH3CN than CH3OH for Ti-BEA, but the opposite trend is observed for Ti-MFI. Ti-silicates with greater silanol densities, however, give greater epoxidation turnover rates than their hydrophobic counterparts in both solvents. Kinetic, spectroscopic, and thermodynamic analyses show that differences in turnover rates mainly arise from changes in the stabilization of reactive surface species by solvent mediated interactions, because the mechanism of the reaction and stability of the fluid-phase reactants remain similar in CH3CN and CH3OH. Specifically, apparent activation free energy values ( Δ G App ‡ ) indicate that surface intermediates responsible for alkene epoxidation are stabilized to a greater extent in CH3CN on Ti-BEA and in CH3OH on Ti-MFI. Hydrophilic Ti-silicates present lower Δ G App ‡ values regardless of solvent identity, which suggests that these differences correspond to the number of hydrogen-bonding solvent molecules found near reactive species bound to Ti active sites. Taken together, these findings demonstrate the role of solvent molecules in allowing reactive intermediates to recognize the properties of active sites beyond the length-scale of covalent bonds, which carry implications for epoxidation but also other reactions within solvent-filled pores of microporous materials.

Summary Natural systems drive the high-energy reactions of photosynthesis with efficient and broadband energy capture. Transition-metal photocatalysts similarly convert light into chemical reactivity, and yet suffer from light-limited operation and require blue-to-UV excitation. In photosynthesis, both light capture and reactivity have been optimized by separation into distinct sites. Inspired by this modular architecture, we synthesized a biohybrid photocatalyst by covalent attachment of the photosynthetic light-harvesting protein R-phycoerythrin (RPE) to the transition-metal photocatalyst tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)3]2+). Spectroscopic investigation found that absorbed photoenergy was efficiently funneled from RPE to [Ru(bpy)3]2+. The utility of the biohybrid photocatalyst was demonstrated via an increase in yields for a thiol-ene coupling reaction and a cysteinyl-desulfurization reaction, including recovered reactivity at red wavelengths where [Ru(bpy)3]2+ alone does not absorb.

Anticipating an increasing demand for hybrid double network (DN) hydrogels in biomedicine and biotechnology, this study evaluated the effects of each network on the mechanical and biological properties. Polyethylene glycol (PEG) (meth)acrylate hydrogels with varied monomer molecular weights and architectures (linear vs. 4-arm) were produced with and without an added ionically bonded alginate network and their mechanical properties were characterized using compression testing. The results showed that while some mechanical properties of PEG single network (SN) hydrogels decreased or changed negligibly with increasing molecular weight, the compressive modulus, strength, strain to failure, and toughness of DN hydrogels all significantly increased with increased PEG monomer molecular weight. At a fixed molecular weight (10 kDa), 4-arm PEG SN hydrogels exhibited better overall mechanical performance; however, this benefit was diminished for the corresponding DN hydrogels with comparable strength and toughness and lower strain to failure for the 4-arm case. Regardless of the PEG monomer structure, the alginate network made a relatively larger contribution to the overall DN mechanical properties when the covalent PEG network was looser with a larger mesh size (e.g., for larger monomer molecular weight and/or linear architecture) which presumably enabled more ionic crosslinking. Considering the biological performance, adipose derived stem cell cultures demonstrated monotonically increasing cell area and Yes-associated protein related mechanosensing with increasing amounts of alginate from 0 to 2 wt.%, demonstrating the possibility for using DN hydrogels in guiding musculoskeletal differentiation. These findings will be useful to design suitable hydrogels with controllable mechanical and biological properties for mechanically demanding applications. STATEMENT OF SIGNIFICANCE: Hydrogels are widely used in commercial applications, and recently developed hybrid double network hydrogels have enhanced strength and toughness that will enable further expansion into more mechanically demanding applications (e.g., medical implants, etc.). The significance of this work is that it uncovers some key principles regarding monomer molecular weight, architecture, and concentration for developing strong and tough hybrid double network hydrogels that would not be predicted from their single network counterparts or a linear combination of the two networks. Additionally, novel insight is given into the biological performance of hybrid double network hydrogels in the presence of adipose derived stem cell cultures which suggests new scope for using double network hydrogels in guiding musculoskeletal differentiation.

Graphene as a prospective cocatalyst can obviously promote the photocatalytic H2-evolution performance of photocatalysts by rapidly transferring photogenerated electrons. For an efficient graphene-modified photocatalytic system for H2 evolution, the fast H2-evolution reaction is as important as the rapid photoelectron transfer via graphene. In this paper, edge-sulfonated graphene (rGO-SO3H) with high H+-adsorbed activity was successfully synthesized by the formation of covalent bonds between graphene and benzenesulfonic acid through a diazotization reaction, which couples with TiO2 nanoparticles to prepare rGO-SO3H/TiO2 photocatalyst for accelerating H2-evolution reaction. The results showed that the rGO-SO3H/TiO2 displayed the highest H2-production rate of 197.1 μmol h−1 g−1 as high as 5.38, 2.81, and 3.40 times of TiO2, rGO/TiO2, and SO3H/TiO2, respectively. The improved efficiency of rGO-SO3H/TiO2 can be attributable to the synergetic action of graphene as a photoelectron cocatalyst and sulfonate ions as H+-adsorbed active sites. This study provides a new insight for the efficient hydrogen-evolution graphene-based photocatalysts.

In this work, a covalent organic framework (COF), which is constructed by the building blocks of [5,10,15,20-tetrakis(4-aminophenyl)porphinato]copper(II) (CuTAPP) and p-benzaldehyde, is employed to integrate with TiO2 for the purpose of establishing a Z-scheme hybrid. Within the system, isonicotinic acid performs the role of a bridge that connects the two components through a coordination bond. Further photocatalytic application reveals the hybrid framework is able to catalyze CO2 conversion under simulated solar light, resulting in CO production rate of 50.5 μmol g−1 h−1, about 9.9 and 24.5 times that of COF and pristine TiO2, respectively. The ameliorated catalytic performance owes much to the porphyrin block acting as photosensitizer that augments the light absorbance, and the establishment of Z-scheme system between the inorganic and organic components that enhances the separation of the carriers. In addition, the chemical bridge also ensures a steady usage and stable charge delivery in the catalysis. Our study sheds light on the development of versatile approaches to covalently incorporate COFs with inorganic semiconductors.

The fabrication of stable and efficient catalysts for green and economic catalytic transformation is significant. Here, highly stable covalent triazine frameworks (CTF-1) were used as the supporting material for anchoring ultrafine Pd nanoparticles (NPs) via a facile impregnation process and a one-pot calcination-reduction strategy. The widespread dispersion of ultrafine Pd NPs was a result of the abundant high nitrogen-content triazine groups of CTF-1 that endowed the catalyst Pd@CTF-1 with high catalytic activity. The catalytic performance of Pd@CTF-1 was demonstrated by the one-pot N-alkylation of benzaldehyde with aniline (or nitrobenzene) under mild reaction conditions, and Pd@CTF-1 exhibited a wide range of general applicability for N-alkylation reactions. The reaction mechanism for the N-alkylation reaction was also studied in detail. In addition, the Pd@CTF-1 catalyst exhibited high thermal and chemical stability, maintaining good catalytic efficiency after multiple reaction cycles. This study provides new insights for the fabrication of organic supporting materials with highly dispersed active catalytic sites that can lead to excellent catalytic performance for efficient, economical, and green reactions.

Herein, the optional and controllable growth of Bi2S3 onto NH2-MIL-125 via covalent conjunction strategy was reported. The experimental results demonstrate that the obtained heterojunction exhibits boosting photocatalytic reduction CO2 and organic dye degradation. The 18-Bi2S3@NH2-MIL-125-SH displays the highest yield of 12.46 μmol g−1h−1 of CO, >13 times that of pure NH2-MIL-125. Meanwhile, the reaction kinetic of 18-Bi2S3@NH2-MIL-125-SH in the degradation of methylene blue is uppermost, which is 160 times than that of the commercial P25. The enhancement of photocatalytic performance could be ascribed to the covalent coordination-driven intimate interfacial interaction in n-scheme heterojunction. Meanwhile, the plausible mechanism was also investigated by UV–vis diffuse reflectance (UV–vis), photoluminescence (PL), electrochemical photocurrent, electron spin resonance (ESR) and electrochemical impedance spectroscopy (EIS).

This study introduces a facile method for synthesizing covalently bonded magnetic carbon nanoparticles (MCNs) in which carboxylic acid-functionalized activated carbon nanospheres (ACN-COOH) are connected with amine-terminated iron oxide nanoparticles (NPs) (Fe3O4-NH2) via a carbodiimide crosslinking reaction. The adsorption characteristics of the developed magnetic nanoparticles (ACN-Fe3O4) were investigated using a standard cationic dye (methylene blue, MB). Two additional MCNs (multi-core and core@shell structures) were also prepared, and their adsorption performances were extensively compared. The developed ACN-Fe3O4 material thoroughly utilizes the strengths of activated carbon and Fe3O4 themselves, exhibiting large specific surface areas (708.4 m2/g) and strong magnetic properties (40.3 emu/g), resulting in high adsorption capacity (349.5 mg/g) and recycling efficiency (76 % of adsorption performance after four cycles). In addition, a study of the mechanism reveals that pore-filling processes are dominant with minor contributions from electrostatic interactions, π–π interactions, and n–π interactions. The developed covalently bonded magnetic carbon nanoparticles (ACN-Fe3O4) can thus be considered as competent adsorbents with the potential to compensate for the drawbacks of contemporary MCNs, such as, low adsorption capacity, and weak magnetic properties.

High–temperature proton exchange membrane fuel cells (HT–PEMFCs) are pursued worldwide as efficient energy conversion devices. Great efforts have been made in the area of designing and developing phosphoric acid (PA)–based proton exchange membrane (PEM) of HT–PEMFCs. This review focuses on recent advances in the limitations of acid–based PEM (acid leaching, oxidative degradation, and mechanical degradation) and the approaches mitigating the membrane degradation. Preparing multilayer or polymers with continuous network, adding hygroscopic inorganic materials, and introducing PA doping sites or covalent interactions with PA can effectively reduce acid leaching. Membrane oxidative degradation can be alleviated by synthesizing crosslinked or branched polymers, and introducing antioxidative groups or highly oxidative stable materials. Crosslinking to get a compact structure, blending with stable polymers and inorganic materials, preparing polymer with high molecular weight, and fabricating the polymer with PA doping sites away from backbones, are recommended to improve the membrane mechanical strength. Also, by comparing the running hours and decay rate, three current approaches, 1. crosslinking via thermally curing or polymeric crosslinker, 2. incorporating hygroscopic inorganic materials, 3. increasing membrane layers or introducing strong basic groups and electron–withdrawing groups, have been concluded to be promising approaches to improve the durability of HT–PEMFCs. The overall aim of this review is to explore the existing degradation challenges and opportunities to serve as a solid basis for the deployment in the fuel cell market.

Constitutionally adaptive chemistry of selenium-containing crown ethers (CEs) offers a new platform for controlling/switching the hydration of bolaamphiphile skeletons in water in an effective and simple manner by the virtue of covalent bonding. The adaptive behaviour of the macrocyclic bolaamphiphiles (transformations between C7SeBola and C7SeOBola) in response to redox environment was found to be a decisive factor.

Two kinds of novel sulfhydryl functionalized covalent organic frameworks were fabricated as adsorbents for the removal of ultra-trace concentrations of Hg2+from water. The two kinds of sulfhydryl functionalized covalent organic frameworks were obtained via a thiol-ene click reaction between the thiol groups of trithiocyanuric acid (TTC) or bismuththiol (BMT) and vinyl groups on the surface of covalent organic frameworks. The material structure was characterized by XRD, SEM, EDS, FT-IR, BET, and TG analysis. Due to their rich sulfur content, both adsorbents (COF-SH-1 and COF-SH-2) exhibited a high level of selective Hg2+ removal from aqueous solution with maximum adsorption capacities of 763.4 mg g−1 and 526.3 mg g−1, respectively. Furthermore, in the presence of ultra-low concentrations of Hg2+ both materials exhibited excellent performance, achieving rapid Hg2+ removal at concentrations from 10 μg L−1 to less than 0.02 ng L−1. Analysis of the adsorption mechanism indicates that the sulfur containing chelating groups exhibit a strong binding capacity for Hg2+. Results show that the structure determines the performance, with the amount of adsorption sites being related to the adsorption capacity. Therefore, as sulfhydryl functionalized covalent organic frameworks contain an abundance of adsorption sites, these materials can effectively achieve the removal of ultra-low trace Hg2+ concentrations and have promising future application potential for the environmental detection of heavy metals.

Ni-rich layered oxides are considered as promising cathode materials for Li-ion batteries (LIBs) due to their satisfying theoretical specific capacity and reasonable cost. However, poor cycling stability caused by structural collapse and interfacial instability of the Ni-rich cathode material limits the further applications of commercialization. Herein, a series of B-doped single-crystal LiNi0.83Co0.05Mn0.12O2 (NCM) are designed and fabricated, aiming to improve the structural stability and enlarge the Li+-ions diffusion paths simultaneously. It reveals that B-doping at TM layers will facilitate the formation of stronger B-O covalent bonds and expand the layered distance, significantly enhancing the thermodynamics and kinetic of NCM electrode. With the synergistic effect of single-crystalline architecture and appropriate B-doping, it can effectively alleviate the occurrence of internal strain with structural degradation and boost the intrinsic rate capability synchronously. As anticipated, the 0.6 mol % B-doped NCM electrode exhibits enhanced rate property and superior cycle stability, even at the harsh condition of high-temperature and elevated cut-off voltage. Remarkably, when tested in pouch-type full-cell, it maintains high reversible capacity with superior capacity retention of 91.35% over 500 cycles with only 0.0173% decay per cycle. This research illustrates the feasibility of B-doping and single-crystalline architecture to improve the electrochemical performance, which is beneficial to understand the enhancement effect and provides the design strategy for the commercialization progress of Ni-rich cathode materials.

With the increasingly serious plastic pollution, people's demand for the multi-functional biodegradable plastics is becoming more and more urgent. Inspired by the crosslinked shape memory polymers, the crosslinked starch films were synthesized by inducing the decomposition of benzophenone into free radical and depriving hydrogen on starch macromolecules under UV irradiation, in order to gain a high shape memory performance. The results showed that a three-dimensional crosslinking network between starch macromolecule chains was formed. Compared with the uncrosslinked starch films, the photo-crosslinked films not only had higher mechanical property (tensile strength increased by 154%), but also had better water resistance (water contact angle from 60° to 87°) due to the reduction of free hydroxyl groups. In addition, the stable covalent bonds serving as netpoints endow photo-crosslinked films with great improvement in shape memory property, with nearly 180° bending recovery. More importantly, the maximum shape memory fixity ratio (Rf) and shape memory recovery ratio (Rr) under stretch deformation were 96.5% and 99.8%, respectively. And the Rf and Rr could reach 94.6% and 79.8% even at higher strain. In all, the excellent shape memory performance and good degradability crosslinked starch films, which have great potential application in disposable heat-shrinkable packaging materials.

We report a series of highly stable metallophthalocyanine-based covalent organic frameworks (MPc-dx-COFs) linked by robust 1,4-dioxin bonds constructed through nucleophilic aromatic substitution (SNAr) reaction. The chemical structures and crystallinity of the COFs largely remain unchanged even after treating with boiling water (90 °C), concentrated acids (12 mol/L HCl) or bases (12 mol/L NaOH), oxidizing (30% H2O2) or reducing agents (1 mol/L NaBH4) for three days due to their stable M-Pc building blocks and resilient dioxin linkers. With metallated phthalocyanine active sites regularly arranged in the stable framework structures, MPc-dx-COFs can be directly used as efficient electrocatalysts for the oxygen reduction reaction (ORR) without pyrolysis treatment that has commonly been used in previous studies.

Molecular separation is critical to mitigating the issues of water contamination and shortage and currently focuses on the use of framework materials fabricated by special building blocks. However, developing a simple and tunable synthesis methodology for materials with alternative permeation and selectivity remains challenging. Here, we fabricate a series of nanochannel membranes composed of uniform spherical covalent organic frameworks (COFs). Diversified spherical COFs have diameters ranging from ∼150 to ∼800 nm, therefore demonstrating a programmable surface charge distribution from −24 to −63 mV. COF membranes with tailor-made surface charge enable different surface energy levels and allow increasing water permeation of 15.5 to 34.5 L m−2 h−1 bar−1. Furthermore, COFs can also act as filters, achieving up to 99.7% rejection and separation of the opposite charged dyes. We expect these COFs with tunable surface charge to be applicable to variety of fields, including sieving, batteries, and water treatments.

This study evaluated the effects of different Z-values on the physical, chemical, and biological properties of β-SiAlON ceramics. Increasing the Z-value of the β-Si3N4 solid solution's main phase resulted in the replacement of Si–N bonds with Al–O bonds. The number of columnar crystals decreased, bulk density increased, and porosity decreased, thus transforming the fine-particle microstructure of β-Si3N4 into the columnar structure of β-SiAlON. The compressive strength increased, which facilitated sintering at 1500 °C without sintering auxiliaries. H+ and OH− ions in deionized water broke the covalent bonds on the β-SiAlON surface, thereby forming new Si–OH, Al–OH, and N–H bonds on the β-SiAlON surface and producing SiO44−, AlO2−, and NH4+ groups in the solution. Increasing the soaking time changed the compositions of ionized H+ and OH− ions, thus increasing the pH. MC3T3-E1 cells were cultured on the β-SiAlON surface, and it was observed that the increase in the Z-value of β-SiAlON had no influence on cell adhesion and spreading, but it may slightly suppress cell proliferation at high Z-values. At low Z-values, the low AlO2− concentration helps promote osteogenic differentiation and mineralized nodule formation. Thus, β-SiAlON ceramics possess excellent physical, chemical, and biological properties and are considered excellent bone-repairing materials.

Porous polymeric covalent organic frameworks (COFs) have been under intense synthetic investigation with over 100 unique structural motifs known. In order to realize the true potential of these materials, converting the powders into thin films with strict control of thickness and morphology is necessary and accomplished through techniques including interfacial synthesis, chemical exfoliation and mechanical delamination. Recent progress in the construction and tailored properties of thin film COFs are highlighted in this review, addressing mechanical properties as well as application-focused properties in filtration, electronics, sensors, electrochemistry, magnetics, optoelectronics and beyond. Additionally, heterogeneous integration of these thin films with other inorganic and organic materials is discussed, revealing exciting opportunities to integrate COF thin films with other state of the art material and device systems.

Semiconductor photocatalysts play an indispensable role in the photocatalytic process. Two-dimensional covalent organic frameworks (2D-COFs), as a kind of innovative photocatalyst, have garnered tremendous attention. Herein, we report an amide-linked 2D-COF (COF-JLU19) with outstanding photocatalytic performance in water, designed through a multi-synergistic approach. The synergistic effects of the high porosity, photoactive framework, high wettability, and stability of COF-JLU19 led to an unprecedented enhancement in the photocatalytic activity and recyclability in water upon illumination by visible light. More importantly, amide-linked 2D-COF based electrospinning membranes were prepared, which also exhibited superior photocatalytic activity for the degradation of Rhodamine B in water with sunlight. This study highlights the potential of the multi-synergistic approach as a universal rule for developing COF-based photocatalysts to address environmental and energy challenges.

Although nearly all oxygen redox reaction (ORR) research has been carried out based on Mn4+-containing layered oxides (Li[Li1−x−yMnxMy]O2) in Li-ion positive electrodes, the roles of Mn(t2g3)−O hybridized band in correlation with ORRs have yet to be understood. Considering the competition of covalent and ionic M O bond features, the two-type Li2MO3 cathode models (i.e., 3d3-Li2MnO3 and 3d0-Li2TiO3) operated by the pure ORRs were investigated using first-principles calculations to unlock veiled critical factors in activating ORRs, and enabling their reversibility upon charging. First, the thermodynamic formation energies showed that the oxygen instability induced by Li+-extraction is much larger for Li2TiO3 than that for Li2MnO3. Second, the [[EQUATION]]-type Mn(t2g3)−O hybridized band in the low energy state for the Mn oxide broadened the O 2p-bandwidth, resulting in weakening the chemical hardness of Mn O in comparison to that of Ti O. Third, the cooperative inter- and intra-layer O O dimerizations ( O dimers were present within the Mn intralayer for Li2MnO3. From this theoretical understanding, we have concluded that the presence of rigid Mn(t2g3)−O band upon charging plays a significant role in easily triggering the oxygen redox, and in suppressing the formation of very short O O dimers leading to O2 release, which are because of the non-overlap between the bonding states of O O and the Mn(t2g3)−O state. The revealed importance of Mn(t2g3)−O band provides an exciting direction for designing ORutilizing high energy density cathodes for lithium-ion batteries.

Sulfur hexafluoride (SF6) is an extremely severe greenhouse gas. It is an urgently important mission to find excellent candidates for selective adsorption of SF6, in order to reduce the emission of SF6 facilities. Here, we adopt the molecular simulation method to systematically explore the selective adsorption of SF6 in 22 kinds of representative covalent-and metal–organic frameworks. Results indicate that COF-6 is a promising candidate for the SF6 adsorption at low pressure P X SF 6 =0.1) and the semiconductor industry ( X SF 6 =0.002) environments, COF-6 and ZIF-8 are fairly promising candidates for selective adsorption of SF6 from the SF6/N2 mixtures, because they not only present the high selectivity, but also the large adsorption capacity at ambient environment, which can be considered as potential adsorbents for selective adsorption of SF6 at ambient conditions.

Hydrogel film composed of chitosan (CS) as raw material was prepared by free radical polymerization. Silicon was introduced into the hydrogel film in different ways (covalent/non-covalent) to improve the physical properties of the film, and β-acids were loaded to enhance the antibacterial activity of the film. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis were used to characterize the structure of films. The mechanical results indicated that when nano-silica (0.3%) was introduced into film (containing 0.2% β-acids) by non-covalently bond, the tensile strength increased to 8.59 MPa. Meanwhile silicon (0.3%) entered the film by covalent bonding, the tensile strength increased to 7.99 MPa. The films loaded with β-acids had well ability to blocks ultraviolet rays and exhibited inhibitory effect on E. coli and S. aureus. In the PBS (37 °C, pH = 7.4) simulant solution, the release mechanism of most films to release the β-acids followed non-Fick diffusion (n > 0.5). It could be concluded that the prepared hydrogel films loading with β-acids had broad application prospects in food packaging material with antibacterial property and controlled release.

Artificial photoreduction of CO2 to chemical fuel is an intriguing and reliable strategy to tackle the issues of energy crisis and climate change simultaneously. In the present study, we rationally constructed a Ni(OH)2-modified covalent triazine-based framework (CTF-1) composites to serve as cocatalyst ensemble for superior photoreduction of CO2. In particular, the optimal Ni(OH)2-CTF-1 composites (loading ratio at 0.5 wt%) exhibited superior photocatalytic activity, which surpassed the bare CTF-1 by 33 times when irradiated by visible light. The mechanism for the enhancement was systematically investigated based on various instrumental analyses. The origin of the superior activity was attributable to the enhanced CO2 capture, more robust visible-light response, and improved charge carrier separation/transfer. This study offers an innovative pathway for the fabrication of noble-metal-free cocatalysts on CTF semiconductors and deepens the understanding of photocatalytic CO2 reduction.