Zhang Fan, Wei Shice, Wei Weiwei, Zou Jiang, Gu Guoying, Wu Dongqing, Bi Shuai, Zhang Fan
School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Robotics Institute, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Sci Bull (Beijing). 2020 Oct 15;65(19):1659-1666. doi: 10.1016/j.scib.2020.05.033. Epub 2020 May 29.
Two-dimensional (2D) olefin-linked covalent organic frameworks (COFs) with excellent π-electron communication and high stability are emerging as promising crystalline polymeric materials. However, because of the limited species of COFs, their characteristics, processability and potential applications have not been completely understood and explored. In this work, we prepared two novel olefin-linked 2D COFs through Knoevenagel condensation of 2,4,6-trimethyl-1,3,5-triazine with tritopic triazine-cored aldehydes. The resulting COFs exhibit highly crystalline honeycomb-like structures stacked from hexagonal-latticed polymeric layers and display well-defined nanofibrillar morphologies with the uniform diameters of ca. 80 nm and ultra-lengths up to several micrometers. Such COF nanofibers can be readily composited with carbon nanotubes into high-quality continuous thin films, which are further compacted by a typical hot-pressing process to enhance their densities and mechanical strength without changing their fibrous microstructures. Such film-fabricated interdigital microelectrodes and the ionogel electrolyte are assembled into planar micro-supercapacitors (MSCs), which exhibit an outstanding areal capacitance of 44.3 mF cm, large operating voltage window of 2.5 V, high volumetric energy density of 38.5 mWh cm as well as excellent cycling stability.
具有优异π电子通信和高稳定性的二维（2D）烯烃连接共价有机框架（COF）正成为有前景的结晶聚合物材料。然而，由于COF种类有限，其特性、可加工性和潜在应用尚未得到充分理解和探索。在这项工作中，我们通过2,4,6-三甲基-1,3,5-三嗪与三嗪核三官能醛的Knoevenagel缩合反应制备了两种新型烯烃连接的二维COF。所得COF呈现出由六边形晶格聚合物层堆叠而成的高度结晶蜂窝状结构，并显示出明确的纳米纤维形态，直径约80nm，长度可达数微米。这种COF纳米纤维可以很容易地与碳纳米管复合成高质量的连续薄膜，通过典型的热压工艺进一步压实以提高其密度和机械强度，而不改变其纤维微观结构。这种由薄膜制成的叉指式微电极和离子凝胶电解质被组装成平面微型超级电容器（MSC），其表现出44.3mF/cm出色的面积电容、2.5V的大工作电压窗口、38.5mWh/cm的高体积能量密度以及出色的循环稳定性。
