High performance carbon supercapacitor electrodes derived from a triazine-based covalent organic polymer with regular porosity

Emerging trends in the development and applications of triazine-based covalent organic polymers: a comprehensive review

Owing to unique structural features, triazine-based covalent organic polymers (COPs) have attracted significant attention and emerged as novel catalysts or support materials for an array of applications. Typically formed by reacting triazine-based monomers or the in situ creation of triazine rings from nitrile monomers, these COPs possess 2D/3D meso/microporous structures held together via strong covalent linkages. The quest for efficient, stable and recyclable catalytic systems globally necessitates the need for a well-structured and comprehensive review summarizing the synthetic methodologies and applications of triazine-based COPs. This review explores the various synthetic routes and applications of these COPs in photocatalysis, heterogeneous catalysis, electrocatalysis, adsorption and sensing. By exploring the latest advancements and future directions, this review offers valuable insights into the synthesis and applications of triazine-based COPs.

Chitosan-Linked Dual-Sulfonate COF Nanosheet Proton Exchange Membrane with High Robustness and Conductivity

2D materials that can provide long-range ordered channels in thin-film form are highly desirable for proton exchange membranes (PEMs). Covalent organic framework nanosheets (CONs) are promising 2D materials possessing intrinsic porosity and high processability. However, the potential of CONs in PEMs is limited by loose sheet stacking and interfacial grain boundary, which lead to unsatisfied mechanical property and discontinuous conduction pathway. Herein, chitosan (CS), a natural polymer with rich NH2 groups, is designed as the linker of dual-sulfonate CONs (CON-2(SO3 H)) to obtain CON-2(SO3 H)-based membrane. Ultrathin CON-2(SO3 H) with high crystallinity and large lateral size is synthesized at water-octanoic acid interface. The high flexibility of CS chains and their electrostatic interactions with SO3 H groups of CON-2(SO3 H) enable effective connection of CON-2(SO3 H), thus endowing membrane dense structure and exceptional stability. The stacked CON-2(SO3 H) constructs regular hydrophilic nanochannels containing high-density SO3 H groups, and the electrostatic interactions between CON-2(SO3 H) and CS form interfacial acid-base pairs transfer channels. Consequently, CON-2(SO3 H)@CS membrane simultaneously achieves superior proton conductivity of 353 mS cm-1 (under 80 °C hydrated condition) and tensile strength of 95 MPa. This work highlights the advantages of proton-conducting porous CON-2(SO3 H) in advanced PEMs and paves a way in fabricating robust CON-based membranes for various applications.

Preparation of N,P Co-doped Porous Carbon Derived from Daylily for Supercapacitor Applications

Biomass-derived activated carbon is a widely used electrode material for supercapacitors. One of the keys to preparing high-performance activated carbon is the selection of appropriate precursors. Daylily is a common edible herb and is widely planted in Asia. It is rich in nitrogen and phosphorus, so it can be used as a precursor of heteroatom-doped activated carbon. Herein, a daylily-derived porous carbon with a large specific surface area and high content of heteroatoms has been successfully prepared by a simple carbonization method. The as-prepared carbon materials showed a remarkable specific capacitance of 299.1 F/g at 0.5 A/g and excellent cycling stability of 99.6% after 4000 cycles at a current density of 1 A/g. Moreover, the assembled symmetric supercapacitor showed a high energy density of 21.6 Wh/kg at a power density of 598.2 W/kg in 6 M KOH electrolyte. These results demonstrate that the daylily-derived porous carbon is an excellent material for high-performance supercapacitors.

Rational design of covalent triazine frameworks based on pore size and heteroatomic toward high performance supercapacitors

A series of covalent triazine frameworks (CTFs) are prepared via ionothermal synthesis for supercapacitors. Due to the feature of adjustable pore structure and rich nitrogen, CTFs with regular structure can be used as a group of model compounds to further investigate the influence of pore size and heteroatom on supercapacitors. By comparing the performance of CTFs with different pore structures and nitrogen contents, the experimental results show that BPY-CTF with high specific surface area of 2278 m² g^-1, mesopores structure, and suitable nitrogen content displays a specific capacitance of 393.6 F g^-1 at 0.5 A g^-1. According to the results and analysis, the existence of mesopores largely enhance the contact area between the electrode material and electrolyte, and then boost the charge transfer. On the other hand, N-doping has a prominent effect on improving the Faradaic pseudo-capacitance and conductivity for CTF electrode materials. This work will inspire further research on the development of highly efficient electrode materials for energy storage devices.

Facile fabrication of silica@covalent organic polymers core-shell composites as the mixed-mode stationary phase for hydrophilic interaction/reversed-phase/ion-exchange chromatography

Covalent organic polymers (COPs) are a promising class of cross-linked polymeric networks that attracted extensive attention in separation and analysis fields. Exploring facile and convenient strategy to prepare COPs-based mixed-mode stationary phases for high performance liquid chromatography (HPLC) has seriously lagged and has never been reported. Herein, we describe a facile in-situ grow strategy for fabrication of silica@COPs core-shell composites (SiO₂@TpBD-(OH)₂) as a novel mixed-mode stationary phase for HPLC. Owing to the co-existing of abundant hydroxyl, carbonyl, imine, cyclohexyl groups, and benzene rings in the skeleton of COPs shell, the developed mixed-mode stationary phase exhibits hydrophilic interaction liquid chromatography (HILIC)/reversed-phase liquid chromatography (RPLC)/ion-exchange chromatography (IEX) retention mechanisms. The content of acetonitrile, pH value, and salt concentration in the mobile phase were investigated on SiO₂@TpBD-(OH)₂ packed column. In comparison to conventional single-mode columns, the SiO₂@TpBD-(OH)₂ column showed flexible selectivity, enhanced separation performance, and superior resolution for benzene homologues, polycyclic aromatic hydrocarbons, nucleosides and bases, and acidic organic compounds. The column efficiency of p-nitrobenzoic acid was up to 54440 plates per meter. The packed column also possessed outstanding chromatographic repeatability for six nucleosides and bases with the RSDs of 0.07-0.23%, 0.58-1.77%, and 0.31-1.23% for retention time, peak area, and peak height, respectively. Besides, the SiO₂@TpBD-(OH)₂ column offered baseline separation of multiple organic pollutants in lake water, which verified its great potential in real sample analysis. Overall, the silica@COPs core-shell composites not only provide a new candidate of mixed-mode stationary phases, but also extend the potential application of COPs in separation science.

Recent Advances on Conductive 2D Covalent Organic Frameworks

As a burgeoning family of crystalline porous copolymers, covalent organic frameworks (COFs) allow precise atomic insertion of organic components in the topology construction to form periodic networks and ordered nanopores. Their 2D networks bear great similarities to graphene analogs, and therefore are essential additions to the 2D family. Here, the electronic properties of conductive 2D-COFs are reviewed and their bonding strategies and structural characteristics are examined in detail. The controlling approaches toward the morphologies of conductive 2D-COFs are further explored, followed by a discussion of their applications in field-effect transistors, photodetectors, sensors, catalysis, and energy storage. Finally, research challenges and forthcoming developments are projected. The resulting survey reveals that the extended porous 2D organic networks with conductive properties will provide great opportunities and essential innovations in various electronics and energy-related fields.

Meso/Microporous Carbons from Conjugated Hyper-Crosslinked Polymers Based on Tetraphenylethene for High-Performance CO2 Capture and Supercapacitor

In this study, we successfully synthesized two types of meso/microporous carbon materials through the carbonization and potassium hydroxide (KOH) activation for two different kinds of hyper-crosslinked polymers of TPE-CPOP1 and TPE-CPOP2, which were synthesized by using Friedel–Crafts reaction of tetraphenylethene (TPE) monomer with or without cyanuric chloride in the presence of AlCl₃ as a catalyst. The resultant porous carbon materials exhibited the high specific area (up to 1100 m² g⁻¹), total pore volume, good thermal stability, and amorphous character based on thermogravimetric (TGA), N₂ adsoprtion/desorption, and powder X-ray diffraction (PXRD) analyses. The as-prepared TPE-CPOP1 after thermal treatment at 800 °C (TPE-CPOP1-800) displayed excellent CO₂ uptake performance (1.74 mmol g⁻¹ at 298 K and 3.19 mmol g⁻¹ at 273 K). Furthermore, this material possesses a high specific capacitance of 453 F g⁻¹ at 5 mV s⁻¹ comparable to others porous carbon materials with excellent columbic efficiencies for 10,000 cycle at 20 A g⁻¹.

Direct Synthesis of Microporous Bicarbazole-Based Covalent Triazine Frameworks for High-Performance Energy Storage and Carbon Dioxide Uptake

In this study a series of bicarbazole-based covalent triazine frameworks (Car-CTFs) were synthesized under ionothermal conditions from [9,9'-bicarbazole]-3,3',6,6'-tetracarbonitrile (Car-4CN) in the presence of molten zinc chloride. Thermogravimetric and Brunauer-Emmett-Teller analyses revealed that these Car-CTFs possessed excellent thermal stabilities and high specific surface areas (ca. 1400 m² /g). The electrochemical performances of this Car-CTF series, investigated by using cyclic voltammetry, showed a highest capacitance of (545 F/g at 5 mV/s), which also exhibited excellent columbic efficiencies of 96.1 % after 8000 cycles at 100 μA/0.5 cm² . The other Car-CTF samples displayed similar efficiencies. Furthermore, based on CO₂ uptake measurements, one of the series showed the highest CO₂ uptake capacities: 3.91 and 7.60 mmol/g at 298 and 273 K, respectively. These results suggest a simple method for the preparation of CTF materials that provide excellent electrochemical and CO₂ uptake performance.

Bulk COFs and COF nanosheets for electrochemical energy storage and conversion

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

New and Advanced Porous Carbon Materials in Fine Chemical Synthesis. Emerging Precursors of Porous Carbons

The efficiency of porous carbons in fine chemical synthesis, among other application fields, has been demonstrated since both the porous structure and chemical surface provide the appropriated chemical environment favoring a great variety of relevant chemical transformations. In recent years, metal organic frameworks (MOFs) and covalent organic frameworks (COFs) have emerged as interesting opportunities in the preparation of porous carbons with improved physico-chemical properties. Direct calcination of MOFs or COFs, in the presence or not of others carbon or heteroatom sources, could be considered an easy and practical approach for the synthesis of highly dispersed heteroatom-doped porous carbons but also new porous carbons in which single atoms of metallic species are present, showing a great development of the porosity; both characteristics of supreme importance for catalytic applications. The goal of this review is to provide an overview of the traditional methodologies for the synthesis of new porous carbon structures together with emerging ones that use MOFs or COFs as carbon precursors. As mentioned below, the catalytic application in fine chemical synthesis of these kinds of materials is at present barely explored, but probably will expand in the near future.

A carbonized porous aromatic framework to achieve customized nitrogen atoms for enhanced supercapacitor performance

A porous aromatic framework serving as a precursor preserves the customized nitrogen atoms in the porous carbons, which endows improved electrochemical properties for high-performance supercapacitor applications.