Nitrogen-enriched ordered mesoporous carbons through direct pyrolysis in ammonia with enhanced capacitive performance
Nitrogen-enriched ordered mesoporous carbons through direct pyrolysis in ammonia with enhanced capacitive performance
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DOI：
10.1039/c3ta11342f
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发表时间：
2013-01-01
影响因子：
11.9
通讯作者：
Dai, Sheng
中科院分区：
文献类型：
--
作者：
Wang, Xiqing;Liu, Chen-Guang;Dai, Sheng
通过软模板法将酚醛树脂和Pluronic嵌段共聚物自组装，可以形成有序的聚合物介孔结构，为制备有序介孔碳(OMC)提供了一种简单的方法。然而，直接合成高含氮量的有机碳复合材料仍然是一个巨大的挑战，这是因为能够与酚醛树脂共聚的氮前驱体的可获得性有限，并且在碳化过程中不会破坏介观结构的有序性和氮含量的显著降低。在这项工作中，我们展示了软模板化聚合物复合材料在氨水中的热解作为一种直接、简便的方法来制备富氮有机化合物(N-OMCs)。这种方法不需要任何含氮碳前体或后处理，而是利用热解过程中氨在高温下分解产生的优先反应和/或用氮物种替换氧的优势。它将碳化、氮官能化和活化结合到一个简单的过程中，生成孔径均匀、比表面积大(高达1400m(2)g(-1))和高氮含量(高达9.3at%)的N-OMCs。更重要的是，只要加热温度不超过800摄氏度，就能很好地保持介观结构的有序性，高于800摄氏度(例如850摄氏度)就会观察到轻微的结构退化。当N-OMC用作对称双电层电容器的电极材料时，与未经NH3处理的样品相比，N-OMC表现出更高的电容(6.8u F cm(-2)比3.2u F cm(-2))和降低的离子扩散阻力。
Self-assembly of phenolic resins and a Pluronic block copolymer via the soft-template method enables the formation of well-organized polymeric mesostructures, providing an easy way for preparation of ordered mesoporous carbons (OMCs). However, direct synthesis of OMCs with high nitrogen content remains a significant challenge due to the limited availability of nitrogen precursors capable of co-polymerizing with phenolic resins without deterioration of the order of mesostructural arrangement and significant diminishment of nitrogen content during carbonization. In this work, we demonstrate pyrolysis of the soft-templated polymeric composites in ammonia as a direct, facile way towards nitrogen-enriched OMCs (N-OMCs). This approach does not require any nitrogen-containing carbon precursors or post-treatment, but takes advantage of the preferential reaction and/ or replacement of oxygen with nitrogen species, generated by decomposition of ammonia at elevated temperatures, in oxygen-rich polymers during pyrolysis. It combines carbonization, nitrogen functionalization, and activation into one simple process, generating N-OMCs with a uniform pore size, large surface area (up to 1400 m(2) g(-1)), and high nitrogen content (up to 9.3 at%). More importantly, the ordering of the meso-structure is well-maintained as long as the heating temperature does not exceed 800 degrees C, above which (e. g., 850 degrees C) a slight structural degradation is observed. When being used as electrode materials for symmetric electric double layer capacitors, N-OMCs demonstrate enhanced capacitance (6.8 mu F cm(-2) vs. 3.2 mu F cm(-2)) and reduced ion diffusion resistance compared to the non-NH3-treated sample.