Covalent Triazine-based Frameworks Research Articles

Rhodium nanoparticles supported on covalent triazine-based frameworks as re-usable catalyst for benzene hydrogenation and hydrogen evolution reaction

Rh@CTF-1 nanomaterial is a highly active (TOF ∼ 31 000 h−1) heterogeneous catalyst for the efficient hydrogenation of benzene under mild and solvent-free conditions.

Covalent triazine-based frameworks as electrodes for high-performance membrane capacitive deionization

Covalent triazine-based frameworks (CTFs) with high nitrogen content, porous structures and low electric resistance were synthesized and applied as membrane capacitive deionization (CDI) electrodes for the first time. The obtained CTFs exhibit abundant micropore structure which provide adsorption site for ion and certain hydrophilicity ensure the whole pore volume is participating. The electrodes of p-CTFs show ideal capacitive behavior with the maximum specific capacitance values of 122.63 F g−1 at a scan rate of 1 mV s−1 under 1 M NaCl solution. Besides, the further membrane capacitive deionization by batch mode experiment exhibits excellent electrosorption capacity of 29.34 mg g−1 under 1.2 V in a 1000 mg L−1 NaCl solution and stable regeneration performance. With the admirable properties mentioned above, the prepared CTFs can offer great opportunities as promising CDI electrodes for application of high-performance desalination.

Efficient Visible-Light-Driven Photocatalytic Hydrogen Evolution on Phosphorus-Doped Covalent Triazine-Based Frameworks.

Seeking efficient visible-light-driven photocatalysts for water splitting to produce H2 has attracted much attention. Chemical doping is an effective strategy to enhance photocatalytic performance. Herein, we reported phosphorus-doped covalent triazine-based frameworks (CTFs) for photocatalytic H2 evolution. Phosphorus-doped CTFs were fabricated by a facile thermal treatment using easily available red phosphorus as the external phosphorus species. The introduction of phosphorus atoms into the frameworks modified the optical and electronic property of CTFs, thus promoting the generation, separation, and migration of photoinduced electron-hole pairs. Consequently, the photocatalytic H2-production efficiency of phosphorus-doped CTFs was greatly improved, which was 4.5, 3.9, and 1.8 times as high as that of undoped CTFs and phosphorus-doped g-C3N4 calcined from melamine and urea, respectively.

Highly Porous Covalent Triazine Frameworks for Reversible Iodine Capture and Efficient Removal of Dye

Porous organic frameworks may be a kind of promising material to address environmental issues such as removing the radioactive vapor wastes in fission as well as coping with organic pollutants of wastewater, due to their excellent porous character and remarkable stability. In this report, a covalent triazine-based framework (CTF-CTTD) with hierarchically porous structure and large pore volume was synthesized via the nitrile trimerization. The CTF-CTTD shows an outstanding adsorption ability for iodine with the uptake value of 387% due to their abundant porosity, triazine units, as well as π–π conjugated structures, which is one of the highest values reported so far for iodine uptake values of solid porous adsorbents. Furthermore, iodine captured in CTF-CTTD can be also released easily from the pore of materials because of the highly porous structure. In addition, CTF-CTTD also presents an excellent adsorptive performance for removing Rhodamine B (RhB) with adsorption capacity of 684.9 mg g–1. These result...

Design and syntheses of MOF/COF hybrid materials via postsynthetic covalent modification: An efficient strategy to boost the visible-light-driven photocatalytic performance

The search of novel visible-light-responsive porous materials is important because they hold great promise for applications in various fields. Herein, we report a novel strategy based on postsynthetic covalent modification for fabrication of hierarchical porous metal-organic frameworks/covalent organic frameworks (MOF/COF) hybrid materials. For the first time, benzoic acid-modified covalent triazine-based frameworks (B-CTF-1) are covalently bonded with MOFs (NH2-MIL-125(Ti) or NH2-UiO-66(Zr)) by using this strategy. Photocatalytic results show that the hydrogen production rate over 15 wt% NH2-MIL-125(Ti)/B-CTF-1 (15TBC) is 360 μmol·h−1·g−1 under visible light irradiation, which is more than twice as much as that of the B-CTF-1. Meanwhile, the hybrid materials show higher stability as compared to the simple heterostructures of MOFs and COFs connected via Van der Waals force. Photoelectrochemical analyses and controlled experiments indicate that the superior photocatalytic performance of the MOF/COF hybrids can be attributed to the formation of amide bonds between B-CTF-1 and MOFs, which facilitate the charge separation efficiency and improve the stability of the photocatalyst. Finally, a possible mechanism to well explain the improved photocatalytic performance of the photocatalytic system was proposed. The present work provides a new idea to construct highly efficient and stable MOF/COF hybrid systems and broaden the applications of COF-based materials.

Functionalized Covalent Triazine Frameworks for Effective CO2 and SO2 Removal.

Building novel frameworks as sorbents remains a highly significant target for key environmental issues such as CO2 or SO2 emissions from coal-fired power plants. Here, we report the construction and tunable pore structure as well as gas adsorption properties of hierarchically porous covalent triazine-based frameworks (CTF-CSUs) functionalized by appended carboxylic acid/sodium carboxylate groups. The densely integrated functionalities on the pore walls bestow strong affinity to the as-made networks toward guest acid gases, in spite of their moderate Brunauer-Emmett-Teller surface areas. With abundant microporosity and integrated carboxylic acid groups, our frameworks deliver strong affinity toward CO2 with considerably high enthalpy (up to 44.6 kJ/mol) at low loadings. Moreover, the sodium carboxylate-anchored framework (termed as CTF-CSU41) shows an exceptionally high uptake of SO2 up to 6.7 mmol g-1 (42.9 wt %) even under a low SO2 partial pressure of 0.15 bar (298 K), representing the highest value for a scrubbing material reported to date. Significantly, such pore engineering could pave the way to broad applications of porous organic polymers.

Integrated adsorption and catalytic degradation of safranine T by a porous covalent triazine-based framework

The structural features of adsorbents and the interactions between adsorbents and adsorbates dominate the removal capacity of porous materials to a certain degree. In this work, we used a bottom-up strategy to select a high-performance catalytic adsorbent with appropriate pore structure characteristics by integrating adsorption and catalytic degradation to wipe off Safranin T (ST) dye. That is, a covalent triazine framework based on tetra(4-cyanophenyl)-ethylene (CTF-TCPE) was synthesized to wipe out ST dye from aqueous solution. Systematic researches including kinetics, equilibrium adsorption and photo-catalysis studies were performed. The micro-layer and hierarchical pore structure, high surface area, large pore volume, high negative Zeta potential and the catalytic degradation of CTF-TCPE play key roles in the removal process of ST. The removal amount reaches 6743 mg g−1 in experiment, which is much higher than most experimental values of the other porous materials reported so far, as far as we know. The removal efficiency can reach as high as 99% even above 1000 ppm ST concentration. Removal process and mechanism analyses show that there are strong electrostatic interactions and π-π interactions between CTF-TCPE and ST. The desorption and kinetics experiments show that there exists catalytic degradation during the adsorption process. In high initial concentration of the dye system, partly multilayer adsorption phenomenon occurs between CTF-TCPE and ST dye. The catalytic degradation and multilayer adsorption combine to result in high removal capacity of CTF-TCPE for ST. The effects of pH and ionic strength on ST removal show that CTF-TCPE can work at wide pH and ionic strength ranges. These results indicate that CTF-TCPE is high-efficiency for removal of ST from aqueous solution. Therefore, the strategy of selecting adsorbents based on the structural characters integrating adsorption and catalytic degradation is efficient for designing and synthesizing high-performance removal materials.

Covalent triazine-based framework for micro solid-phase extraction of parabens

Herein, nano-sized covalent triazine-based framework grafted magnetic particles were synthesized by a facile Friedel-Crafts reaction between cyanuric chloride as node and biphenyl as linker. The formation of the material has been confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission-scanning electron microscopy, thermogravimetric analysis, and N2 adsorption-desorption measurement. With respect to the material structure, the large number of aromatic rings in the molecular framework provided a bed for extracting aromatic ring-containing compounds through π-π stacking interactions. The applicability of the prepared material as a new sorbent for micro solid-phase extraction of parabens was investigated. The effect of key experimental parameters affecting the extraction efficiency of the analytes including sorbent amount, sample pH, extraction time and desorption conditions were investigated. High-performance liquid chromatography with UV detection was used for determining the enriched analytes. The method was successfully applied for determining parabens in human urine, breast milk, personal care products, and shower wastewater. After optimization, the linearity range of 0.1–500 μg L−1 and detection limit of 0.02 μg L−1 were obtained for all the selected parabens. The relative standard deviations and recoveries for the real sample analysis were in the range of 2.3–5.0% and 86–102%, respectively.

Rational Design of Porous Covalent Triazine-Based Framework Composites as Advanced Organic Lithium-Ion Battery Cathodes.

In an effort to explore the use of organic high-performance lithium ion battery cathodes as an alternative to resolve the current bottleneck hampering the development of their inorganic counterparts, a rational strategy focusing on the optimal composition of covalent triazine-based frameworks (CTFs) with carbon-based materials of varied dimensionalities is delineated. Two-dimensional reduced graphene oxide (rGO) with a compatible structural conformation with the layered CTF is the most suitable scaffold for the tailored mesopores in the polymeric framework, providing outstanding energy storage ability. Through facile ionothermal synthesis and structure engineering, the obtained CTF-rGO composite possesses a high specific surface area of 1357.27 m2/g, and when used as a lithium ion battery cathode it delivers a large capacity of 235 mAh/g in 80 cycles at 0.1 A/g along with a stable capacity of 127 mAh/g over 2500 cycles at 5 A/g. The composite with modified pore structure shows drastically improved performance compared to a pristine CTF, especially at large discharge currents. The CTF-rGO composite with excellent capacity, stability, and rate performance shows great promise as an emerging high-performance cathode that could revolutionize the conventional lithium-ion battery industry.

Direct Synthesis of a Covalent Triazine‐Based Framework from Aromatic Amides

There have been extensive efforts to synthesize crystalline covalent triazine-based frameworks (CTFs) for practical applications and to realize their potential. The phosphorus pentoxide (P2 O5 )-catalyzed direct condensation of aromatic amide instead of aromatic nitrile to form triazine rings. P2 O5 -catalyzed condensation was applied on terephthalamide to construct a covalent triazine-based framework (pCTF-1). This approach yielded highly crystalline pCTF-1 with high specific surface area (2034.1 m2 g-1 ). At low pressure, the pCTF-1 showed high CO2 (21.9 wt % at 273 K) and H2 (1.75 wt % at 77 K) uptake capacities. The direct formation of a triazine-based COF was also confirmed by model reactions, with the P2 O5 -catalyzed condensation reaction of both benzamide and benzonitrile to form 1,3,5-triphenyl-2,4,6-triazine in high yield.

MoS2 Quantum Dots-Modified Covalent Triazine-Based Frameworks for Enhanced Photocatalytic Hydrogen Evolution.

MoS2 quantum dots (QDs)-modified covalent triazine-based framework (MoS2 /CTF) composites are synthesized through an in situ photodeposition method. MoS2 QDs are well distributed and stabilized on the layers of CTFs by coordination of the frameworks to MoS2 . The QDs-sheet interactions between MoS2 and CTFs facilitate interfacial charge transfer and separation. As a consequence, the composites exhibit outstanding photocatalytic activity and stability for hydrogen evolution under visible light irradiation (λ≥420 nm), that exceed those over pristine CTFs and MoS2 -modified g-C3 N4 (MoS2 /g-C3 N4 ) composite, making them promising materials for solar energy conversion.

Magnetic covalent triazine-based frameworks as magnetic solid-phase extraction adsorbents for sensitive determination of perfluorinated compounds in environmental water samples.

Covalent organic frameworks (COFs), which are a new type of carbonaceous polymeric material, have attracted great interest because of their large surface area and high chemical and thermal stability. However, to the best of our knowledge, no work has reported the use of magnetic COFs as adsorbents for magnetic solid-phase extraction (MSPE) to enrich and determine environmental pollutants. This work aims to investigate the feasibility of using covalent triazine-based framework (CTF)/Fe2O3 composites as MSPE adsorbents to enrich and analyze perfluorinated compounds (PFCs) at trace levels in water samples. Under the optimal conditions, the method developed exhibited low limits of detection (0.62-1.39 ng·L-1), a wide linear range (5-4000 ng L-1), good repeatability (1.12-9.71%), and good reproducibility (2.45-7.74%). The new method was successfully used to determine PFCs in actual environmental water samples. MSPE based on CTF/Fe2O3 composites exhibits potential for analysis of PFCs at trace levels in environmental water samples. Graphical abstract Magnetic covalent triazine-based frameworks (CTFs) were used as magnetic solid-phase extraction adsorbents for the sensitive determination of perfluorinated compounds in environmental water samples. PFBA perfluorobutyric acid, PFBS perfluorobutane sulfonate, PFDA perfluorodecanoic acid, PFDoA perfluorododecanoic acid, PFHpA perfluoroheptanoic acid, PFHxA perfluorohexanoic acid, PFHxS perfluorohexane sulfonate, PFNA perfluorononanoic acid, PFOA perfluorooctanoic acid, PFPeA perfluoropentanoic acid, PFUdA Perfluoroundecanoic acid.

Transition metal decorated covalent triazine-based frameworks as a capacity hydrogen storage medium

From ab initio density functional theory (DFT) calculations, the structural stability and hydrogen adsorption capacity of transition metal (TM, TM = Sc, Ti, V, Cr, Mn) decorated covalent triazine-based framework (CTF) are discussed. It is found that by calculation, these TM atoms can adsorb on the CTF sheet without clusters. The Sc, Ti, V, Cr and Mn decorated CTF are predicated to bind five, four, three, three and two of hydrogen molecules. We found that Sc and Ti decorated CTF are suitable candidates for effective reversible hydrogen storage at near ambient condition, whereas V, Cr and Mn decorated CTF are not promising materials due to too large average bind energies per hydrogen molecule.

A covalent triazine-based framework from tetraphenylthiophene and 2,4,6-trichloro-1,3,5-triazine motifs for sensing o-nitrophenol and effective I2 uptake

A covalent triazine-based framework with a tetraphenylthiophene (TTPT) backbone was prepared by the AlCl3 catalyzed Friedel–Crafts reaction of commercially available material 2,4,6-trichloro-1,3,5-triazine with tetraphenylthiophene in dichloromethane.

Efficient visible light-driven water oxidation and proton reduction by an ordered covalent triazine-based framework

Efficient visible light driven water splitting on a covalent triazine-based framework with a controlled degree of conjugation.

Sulfonated covalent triazine-based frameworks as catalysts for the hydrolysis of cellobiose to glucose.

Covalent triazine-based frameworks (CTFs) were synthesized in large scale from various monomers. The materials were post-synthetically modified with acid functionalities via gas-phase sulfonation. Acid capacities of up to 0.83 mmol g−1 at sulfonation degrees of up to 10.7 mol% were achieved. Sulfonated CTFs exhibit high specific surface area and porosity as well as excellent thermal stability under aerobic conditions (>300 °C). Successful functionalization was verified investigating catalytic activity in the acid-catalyzed hydrolysis of cellobiose to glucose at 150 °C in H2O. Catalytic activity is mostly affected by porosity, indicating that mesoporosity is beneficial for hydrolysis of cellobiose. Like other sulfonated materials, S-CTFs show low stability under hydrothermal reaction conditions. Recycling of the catalyst is challenging and significant amounts of sulfur leached out of the materials. Nevertheless, gas-phase sulfonation opens a path to tailored solid acids for application in various reactions. S-CTFs form the basis for multi-functional catalysts, containing basic coordination sites for metal catalysts, tunable structural parameters and surface acidity within one sole system.

Size-controlled synthesis of CdS nanoparticles confined on covalent triazine-based frameworks for durable photocatalytic hydrogen evolution under visible light.

CdS nanoparticle-decorated covalent triazine-based frameworks (CdS NPs/CTF-1) were controllably synthesized via a facile one-pot solvothermal method. Due to the Lewis basic nature of well-defined nitrogen sites in triazine units of CTF-1, highly dispersed and size-controlled CdS NPs were obtained and stabilized on the surface of CTF-1 layers. The as-prepared CdS NPs/CTF-1 assembly showed higher photocatalytic activity in a hydrogen evolution reaction under visible light irradiation as compared with pure CdS and CTF-1 and their physical mixture. The superior photocatalytic performance observed over CdS NPs/CTF-1 was ascribed to the highly dispersed CdS NPs with strong interaction to CTF-1 layers. The strong NP-on-layer interactions between CdS and CTF-1 in the CdS NPs/CTF-1 assembly can not only facilitate the photogenerated charge separation rates, but can also shape CdS with a nanosized structure and high stability. This study develops a new strategy to improve the photocatalytic performance and conquer the photocorrosion of CdS, and also provides some guidance for us in the development of other CTF-incorporated nanocomposite photocatalysts.

Pd nanoparticles supported on a covalent triazine-based framework material: an efficient and highly chemoselective catalyst for the reduction of nitroarenes

Well-dispersed Pd nanoparticles supported on a triazine-based framework were prepared and the material displayed excellent catalytic activity for the transfer hydrogenation of nitroarenes.

Adsorptive removal of Cd2+ from aqueous solutions by a highly stable covalent triazine-based framework

Porous crystalline materials such as covalent organic frameworks (COFs) have gained tremendous popularity in multidisciplinary areas of science and technology.

Conductive Microporous Covalent Triazine-Based Framework for High-Performance Electrochemical Capacitive Energy Storage.

Nitrogen-enriched porous nanocarbon, graphene, and conductive polymers attract increasing attention for application in supercapacitors. However, electrode materials with a large specific surface area (SSA) and a high nitrogen doping concentration, which is needed for excellent supercapacitors, has not been achieved thus far. Herein, we developed a class of tetracyanoquinodimethane-derived conductive microporous covalent triazine-based frameworks (TCNQ-CTFs) with both high nitrogen content (>8 %) and large SSA (>3600 m2 g-1 ). These CTFs exhibited excellent specific capacitances with the highest value exceeding 380 F g-1 , considerable energy density of 42.8 Wh kg-1 , and remarkable cycling stability without any capacitance degradation after 10 000 cycles. This class of CTFs should hold a great potential as high-performance electrode material for electrochemical energy-storage systems.