Zhang Wang, Cai Guorui, Wu Rui, He Zhen, Yao Hong-Bin, Jiang Hai-Long, Yu Shu-Hong
Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, Hefei Science Center of CAS, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang, 310014, P. R. China.
Small. 2021 Dec;17(48):e2004140. doi: 10.1002/smll.202004140. Epub 2021 Feb 1.
A kind of metal-organic framework (MOF) aerogels are synthesized by the self-assembly of uniform and monodisperse MOF nanofibers. Such MOF nanofiber aerogels as carbon precursors can effectively avoid the aggregation of nanofibers during calcination, resulting in the formation of well-dispersed hollow porous carbon nanofibers (HPCNs). Moreover, HPCNs with well-dispersion are investigated as sulfur host materials for Li-S batteries and electrocatalysts for cathode oxygen reduction reaction (ORR). On the one hand, HPCNs act as hosts for the encapsulation of sulfur into their hierarchical micro- and mesopores as well as hollow nanostructures. The obtained sulfur cathode exhibits excellent electrochemical features, good cycling stability and high coulombic efficiency. On the other hand, HPCNs exhibit better electrocatalytic activity than aggregated counterparts for ORR. Furthermore, a highly active single atom electrocatalyst can be prepared by the carbonization of bimetallic MOF nanofiber aerogels. The results indicate that well-dispersed HPCNs show enhanced electrochemical properties in contrast to their aggregated counterparts, suggesting that the dispersion situation of nanomaterials significantly influence their final performance. The present concept of employing MOF nanofiber aerogels as precursors will provide a new strategy to the design of MOF-derived nanomaterials with well-dispersion for their applications in energy storage and conversion.
一种金属有机框架（MOF）气凝胶通过均匀且单分散的MOF纳米纤维自组装合成。这种作为碳前驱体的MOF纳米纤维气凝胶能够有效避免煅烧过程中纳米纤维的聚集，从而形成分散良好的中空多孔碳纳米纤维（HPCN）。此外，对分散良好的HPCN作为锂硫电池的硫主体材料和阴极氧还原反应（ORR）的电催化剂进行了研究。一方面，HPCN作为主体将硫封装在其分级微孔和介孔以及中空纳米结构中。所得到的硫阴极表现出优异的电化学特性、良好的循环稳定性和高库仑效率。另一方面，HPCN在ORR方面比聚集的对应物表现出更好的电催化活性。此外，通过双金属MOF纳米纤维气凝胶的碳化可以制备出高活性的单原子电催化剂。结果表明，与聚集的对应物相比，分散良好的HPCN表现出增强的电化学性能，这表明纳米材料的分散情况显著影响其最终性能。采用MOF纳米纤维气凝胶作为前驱体的当前概念将为设计用于能量存储和转换的具有良好分散性的MOF衍生纳米材料提供一种新策略。
