氮/硫共掺杂木质素基分级多孔微纳米碳球构建及其电容特性

Lignin is the second most abundant ingredient in wood after cellulose. However, a large amount of lignin is directly discharged into river or burnt for providing heat after enriching due to its complex structures. Recently, the author has researched the controllable preparation and formation mechanism of lignin hollow nanospheres with a single hole. In this project, the advantages of high carbon content of lignin and the controllable hole structure of the lignin hollow nanospheres will be applied. Exisiting some problems of supercapacitor electrode materials, which include a higher raw material costs or toxicity, and the diffculty of fabrication the hierarchical porous structure and controlling the doping element content, will be considered. The thiol-ene click reaction will be employed for realizing chemical crosslinking between lignin molecules, leading to the fact that the structure strength of the lignin hollow nanospheres will be improved. In the meantime, nitrogen and sulfur co-doping will be realized. The objective is to prepare nitrogen and sulfur co-doped lignin-based hierarchical porous micro-nano carbon spheres. The influence mechanism of porous structure and doping element content on the capacitance characteristic of micro-nano carbon spheres will be revealed. The author is hoping to obtain the new supercapacitor electrode material with high specific capacitance. This reasearch will provide new idea and research foundation for value-added application of lignin and even comprehensive application of plantation.

木质素是木材中仅次于纤维素的化学成分，但其复杂的无定形结构致使大量木质素都被直接排入江河污染环境或浓缩后烧掉用以提供热量。木质素的纳米化能为木质素高值化利用提供新途径。本项目预在前期中空开口木质素微纳米球可控制备与形成机理研究的基础上，利用木质素高碳含量以及中空开口木质素微纳米球可调孔结构的优势，结合超级电容器电极材料面临的构建分级多孔结构和掺杂元素含量调控难、原料成本或毒性较高的问题，通过巯基-烯基点击反应实现组成中空开口木质素微纳米球的木质素分子之间产生化学交联，改善结构强度，同时进行氮/硫共掺杂，构建氮/硫共掺杂木质素基分级多孔微纳米碳球，揭示多孔结构和掺杂元素含量对木质素基微纳米碳球电极材料电容特性的影响机理，以期获得新型高比电容的超级电容器电极材料，为木质素的高值化应用乃至人工林木材综合利用提供新思路及基础研究储备。

木质素是木材中仅次于纤维素的化学成分，但其复杂的无定形结构致使大量木质素都被直接排入江河污染环境或浓缩后燃烧用以提供热量。本研究以酶解木质素为原料，探究非极性试剂添加对自组装微纳米球形貌影响规律，构筑实心和中空结构可控的木质素微纳米球，解析形成机理；利用木质素分子在水热和热氧刺激下易于缩合的特点，构筑自交联实心和中空木质素微纳米球，并在此基础上对微纳米球进行化学修饰，解析自交联或化学修饰微纳米球形成和演化机理；进一步对微纳米球碳化或碳化活化处理，构筑实心、中空、多孔和掺杂木质素基微纳米碳球，揭示不同制备条件、形貌结构、孔结构、掺杂元素含量对其电化学性能影响机制，获得高比电容的木质素基分级多孔微纳米碳球电极材料。研究发现，二叔丁基对甲酚能调控木质素微纳米球结构，水热和热氧刺激能明显改善木质素微纳米球结构强度，碳化或碳化活化后能获得形貌规整的木质素微纳米碳球，通过改变微纳米碳球形貌、活化条件、碳化温度能实现微纳米碳球孔隙结构调控，通过聚乙烯亚胺和三聚氰胺能实现对微纳米球进行氮掺杂。实心木质素基微纳米碳球表现出良好的双电层电容特性，且电容达147 F g-1，并经过10000次恒电流充放电循环后，其电容保持率仍高于80%。相比实心木质素基微纳米碳球，相同碳化温度下制备的中空木质素基微纳米碳球比电容提高了23%，多孔木质素基微纳米碳球比表面积增加了近3倍、比电容提高了1倍，氮掺杂能进一步提高微纳米碳球电化学性能。该研究为木质素的高值化应用乃至人工林木材综合利用提供新思路及基础研究储备。