Two-dimensional Polymers: Preparation, Assembly and High-efficiency Electrochemical Applications

Two-dimensional polymers (2DPs) are molecular sheets of atomic layer thickness with periodic arrangements in a two-dimensional plane connected by covalent bonds. They have drawn much attention in recent years because of their lightweight, flexibility, adjustable structure, and high adaptability. Graphene is a unique natural 2DP, with a honeycomb lattice connected by sp(2) hybridized carbon atoms. Due to its excellent conjugated structure and stability, graphene has huge application potential in energy storage, environment, and biomedicine. However, there is a strong p-p stacking effect between two-dimensional graphene sheets, which leads to its poor dispersion and limits its performance in practical applications. To address the above issues, our group has developed strategies for the preparation of three-dimensional-graphene (3DG) nanocomposites with a series of electrochemically active materials for efficient electrochemical energy storage. What's more, inspired by graphene, new kinds of 2DP materials have been developed, such as two-dimensional covalent organic framework (2D COF) and two-dimensional covalent triazine framework (2D CTF). We hope to develop facile preparation methods for high-quality 2DPs. Through the effective assembly, combination, and functional modification, large-scale applications of 2DP in the field of electrochemical energy storage and conversion can be realized. The controllable preparation of 2DPs is of great significance to the study of the relationship between the structure and performance of 2DPs. This article first focuses on rapid preparation, assembly, functional composite, and electrochemical applications of the natural two-dimensional graphene. Then, the preparation methods and effective molecular design of 2D COF, silicene, and 2D CTF are summarized. The article provides ideas for the controllable preparation and efficient application of 2DPs with an emphasis on the structure-property relationship of 2DPs.