Covalent triazine frameworks (CTFs) are a class of unique two-dimensional nitrogen-rich triazine framework with adjustable chemical and electronic structures, rich porosity, good stability and excellent semiconductivity, which enable great various applications in efficient gas/molecular adsorption and separation, energy storage and conversion, especially photo- and electro-catalysis. Different synthesis strategies strongly affect the morphology of CTFs and play an important role in their structure and properties. In this concept, we provide a comprehensive and systematic review of the synthesis methods such as ionothermal synthesis, phosphorus pentoxide catalytic method, polycondensation and ultra-strong acid catalyzed method, and applications of CTFs in photo- and electro-catalysis. Finally we offer some insights into the future development progress of CTFs materials for catalytic applications.

Covalent organic frameworks (COFs) have emerged as promising electrode materials for rechargeable metal-ion batteries and have gained much attention in recent years due to their high specific surface area, inherent porosity, tunable molecular structure, robust framework, and abundant active sites. Moreover, compared with inorganic materials and small organic molecules, COFs have the advantages of multi-electron transfer, short pathways, and high cycling stability. Although great progress on COF-based electrodes has been made, the corresponding electrochemical performance is still far from satisfactory for practical applications. In this review, we first summarize the fundamental background of COFs, including the species of COFs (different active covalent bonds) and typical synthesis methods of COFs. Then, the key challenges and the latest research progress of COF-based cathodes and anodes for metal-ion batteries are reviewed, including Li-ion batteries, Na-ion batteries, K-ion batteries, Zn-ion batteries, et al. Moreover, the effective strategies to enhance electrochemical performance of COF-based electrodes are presented. Finally, this review also covers the typical superiorities of COFs used in energy devices, as well as providing some perspectives and outlooks in this field. We hope this review can provide fundamental guidance for the development of COF-based electrodes for metal-ion batteries in the further research.

The development of solid-state electrolytes (SSEs) with high ionic conductivity, outstanding electrochemical window, and promising mechanical strength is a key factor in realizing the commercialization of high energy density solid-state lithium metal batteries (LMBs). Covalent organic frameworks (COFs) are a functional crystalline material with highly customizable molecular networks and one-dimensional channel structures, thus showing great potential applications in SSEs. Herein, we design flexible COF-poly(vinyl ethylene carbonate) (PVEC) (abbreviated as COF-PVEC) composite electrolyte films with excellent ionic conductivity and high mechanical strength, enabling dendrite-free and long-term running solid-state LMBs. Owing to the lithium-philic triazine and carbon–carbon double bonds groups in the COF skeleton, the obtained flexible COF-PVEC shows high ionic conductivity up to 1.11 × 10⁻⁴ S·cm⁻¹ at 40 °C, and enlarged electrochemical window up to 4.6 V (vs. Li⁺/Li) compared with pure PVEC electrolyte. At the same time, the lithium dendrites are efficiently inhibited after discharge–charging cycles, due to the improved Young’s modulus (150 MPa) and ordered channels of COF. Using the various features of COF-PVEC, we assembled a solid-state full battery with LiFePO₄ cathode, which showed superior rate capacity (151.8, 146.2, 139.2, 128.1, 113.7, and 100.8 mAh·g⁻¹ at 0.1, 0.2, 0.5, 1, 1.5, and 2 C, respectively) and excellent long-term cycling stability (over 400 cycles at 1 C). We believe that the COF-based composite electrolyte can become one of the most promising high-performance SSEs for solid-state LMBs.

As a promising graphene analogue, two-dimensional (2D) polymer nanosheets with unique 2D features, diversified topological structures and as well as tunable electronic properties, have received extensive attention in recent years. Here in this review, we summarized the recent research progress in the preparation methods of 2D polymer nanosheets, mainly including interfacial polymerization and solution polymerization. We also discussed the recent research advancements of 2D polymer nanosheets in the fields of energy storage and conversion applications, such as batteries, supercapacitors, electrocatalysis and photocatalysis. Finally, on the basis of their current development, we put forward the existing challenges and some personal perspectives.