胺基功能化石墨烯量子点的大规模制备及其高电容三维电极的构筑

In this project, we develop the growth, on a gram scale, of nearly monolayer and single-crystalline graphene quantum dots (GQDs) with high specific surface area, high stability, good electrical conductivity and high water-solubility by a novel bottom-up approach-the alkali-catalyzed molecular fusion route. A large number of redox active positions in the edge are introduced through the in-situ amino functional. We design that high conductivity super-long titanium dioxide nanotube arrays act as the three-dimensional ordered current collector, and GQDs of rich in nitrogen active positions act as highly redox-active material. Supercapacitors with the ultra-high capacity and long life are manufactured by the controllable methods of electrophoresis or dipping assembly. Meanwhile, amino-functionalized GQDs as reactive molecules bridges and spacer, due to the strong bonds between amino and carboxyl, carboxyl functionalized graphene sheets are assembled into a large three-dimension connected network, which contributes to solve a difficult common problem that the capacitance of graphene sheets is far lower than the theoretical value caused by the agglomeration and restack. By the controllable preparation of amino-functionalized GQDs and the construction of three-dimensional electrodes, we can fabricate the new type of environmentally friendly, low-cost supercapacitors with high capacity performance, which can raise core competitiveness of our country in fields of energy storage.

本项目发展自下而上碱催化水相分子融合法，大规模（克量甚至千克规模）、低成本、环境友好地制备高比表面积、高稳定性、良好导电性、高水溶性的近单层单晶石墨烯量子点，并通过原位胺基功能化在边位上引入大量的redox活性位。以高导电性超长二氧化钛纳米管阵列为三维有序集流体，富含氮活性位的石墨烯量子点为高活性物质，通过可控的电泳或浸渍组装的方法，制造具有超高面容量的长寿命超级电容器。同时探索以胺基功能化的石墨烯量子点为活性分子桥梁和间隔相，通过边位上胺基与羧基之间的强键作用，将羧基功能化的石墨烯片组装成超大的三维连通网络，尝试解决制造石墨烯超级电容器时难克服的一个共性问题- - -石墨烯片堆叠和团聚导致电容量远低于理论值。通过胺基功能化石墨烯量子点的可控制备及其三维电极的构筑，有望自主研发出高电容性能、环保、低成本的新型超级电容器，从而提升我国在能量存储领域的核心竞争力。

超级电容器具有功率密度高、充放电速度快、循环寿命长等特点，在混合动力汽车、电信通讯、军事等领域有着广阔的应用市场。与电池相比，超级电容器具有高的功率密度，但是它低的能量密度限制其应用，因此开发出高能量密度、高功率密度且使用寿命长的超级电容器是目前研究的热点。石墨烯量子点具有小尺寸组装优势、高导电性、高比表面积、高的化学稳定性和丰富的官能团等特性，可以作为高活性物质应用于超级电容器领域。本项目采用一种新颖的自下而上碱催化水相分子融合法，制备出比表面积大、稳定性高、导电性和水溶性好的高度氮掺杂的石墨烯量子点，其表面带有大量的氧化还原活性位，具有高赝电容活性。设计二维高导电二氧化钛纳米管阵列、三维石墨水凝胶、分层多维碳纳米管/碳布和MOF衍生的多孔碳/碳纳米管作为基底，通过优化其空间构造，增强其表面积，形成利于电子传输和离子扩散的多孔内连通的多维度结构，提升其双电层电容性能。以高度氮掺杂的单晶石墨烯量子点为活性材料，采用电泳法将其负载到基底上，适当调控量子点的负载量及赝电容贡献，在保持基底的高循环稳定性和快速充放电的同时，大幅度提升比容量和能量密度。通过制备这些氮掺杂石墨烯量子点复合材料，构筑出具有高比容量、高能量密度、高功率密度和循环稳定性好的超级电容器。同时，作为电化学性能优异的电极材料，氮掺杂石墨烯量子点复合电极在锂离子电池领域也展示出很好的应用前景。