Self-templated synthesis of uniform hollow spheres based on highly conjugated three-dimensional covalent organic frameworks

• Published in: Nature communications Vol. 11; no. 1; pp. 5561 - 8
• Main Authors: Liu, Yuan-Yuan, Li, Xiang-Chun, Wang, Shi, Cheng, Tao, Yang, Huiyan, Liu, Chen, Gong, Yanting, Lai, Wen-Yong, Huang, Wei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.11.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 147/143; 639/301/299/1013; 639/638/298/921; Capacitance; Covalence; Crystal structure; Crystallinity; Diameters; Electrode materials; Electrolytes; Humanities and Social Sciences; Lithium; Lithium ions; Morphology; multidisciplinary; Ostwald ripening; Polymers; Porous materials; Science; Science (multidisciplinary); Spheres
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-18844-4

Covalent organic frameworks (COFs) have served as a family of porous crystalline molecules for various promising applications. However, controllable synthesis of COFs with uniform morphology is paramount yet still remains quite challenging. Herein, we report self-templated synthesis of uniform and unique hollow spheres based on highly conjugated three-dimensional (3D) COFs with diameters of 500–700 nm. A detailed time-dependent study reveals the continuous transformation from initial nano sphere-like particles into uniform hollow spherical structures with Ostwald ripening mechanism. Particularly, the resulting 3D COF (3D-Sp-COF) is prone to transport ions more efficiently and the lithium-ion transference number ( t + ) of 3D-Sp-COF reaches 0.7, which even overwhelms most typical PEO-based polymer electrolytes. Inspiringly, the hollow spherical structures show enhanced capacitance performance with a specific capacitance of 251 F g −1 at 0.5 A g −1 , which compares favorably with the vast majority of two-dimensional COFs and other porous electrode materials. Covalent organic frameworks (COFs) are promising porous crystalline materials but controllable synthesis of COFs with uniform morphology remains challenging. Here, the authors report a self-templated synthesis of uniform and unique hollow spheres based on highly conjugated three-dimensional COFs.