石墨烯三维宏观材料有序自组装及其对偶氮染料吸附机制的研究

The assembly of graphene nanosheets into three-dimensional macrostructures is a very promising “bottom-up” nanotechnology, and the corresponding graphene-based architectures has been recognized as one type of rising material in the field of environmental purification. For the issues that the disordered structure obtained from self-assembly usually limits pollutants diffusion on macromaterials and the ordered structure obtained from template-directed method is hard for structure control, preparation of three-dimensional macrostructures with ordered alignment of graphene nanosheets via self-assembly process is proposed for the first time in this project, to promote pollutants adsorption and be easy for structure regulation. Based on the functional groups control on different positions of graphene nanosheets (surface or edge), the nanosheets are expected to spontaneously ordered-arrange under the selective reaction of cross-linking agents with these goups, resulting into directional guidance. The ordered self-assembly mechanisms, structure evolution process, as well as regulation factors will be systematically investigated. Such architectures are used as adsorbent to remove azo dyes, which is one type of major environmental pollutants and whose by-products after azo-group fracture have carcinogenic, teratogenesis, and mutagenesis effects. Furthermore, the pore size and surface electrical property are regulated in these graphene-based macrostructures to study their effect on adsorption of azo dyes, subsequently, establish the corresponding structure-activity relationship between them. This project is hope to provide a new model method for ordered assembly of three-dimensional graphene-based macrostructures, which has an important value to drive the controllable synthesis of graphene-based macromaterials and their application in environmental purification.

以石墨烯纳米片层为基元体构建三维多级结构的宏观材料是一项备受关注的“自下而上”纳米技术，相应的石墨烯宏观体在环境领域被认为是一种新型的高效净化材料。针对目前自组装合成的无序结构限制污染物分子扩散以及模板法诱导的有序结构难以调控的问题，本项目提出基于自组装过程制备内部结构有序排列的石墨烯三维宏观吸附材料，以利于污染物分子快速扩散且结构性质可控；拟通过控制石墨烯片层表面和边缘不同位置上的官能团以及其与特定交联剂的定向作用来自发引导石墨烯纳米片层有序排列，并深入探讨其有序自组装机制、结构演化过程和调控因素。结合实际需求，从孔隙尺寸和表面电性两条路径对有序石墨烯宏观体进行调控，研究其对典型污染物偶氮染料（偶氮基断裂产物具“三致”效应）的吸附去除性能，探明两者之间的构效关系。预期成果不仅可为石墨烯三维宏观体的有序组装建立一种新方法，同时对推动石墨烯宏观材料的可控制备与环境应用具有重要价值。

以石墨烯纳米片层为基元体，通过“自下而上”的纳米技术构建的多级结构石墨烯三维（3D）宏观材在水环境领域被视为理想的净化材料。然而在去除有机染料大分子这种特定污染物时，石墨烯宏观材料的微观结构和整体性能仍无法匹配性地达到实际需求，尤其是大分子污染物在石墨烯3D材料内部传质受限的问题。.本项目从石墨烯纳米片层改性和组装过程诱导两条路径入手，调控石墨烯基元体在3D宏观体内部的交联方式，构筑无障碍内部传质通道，提高有机染料大分子在石墨烯材料内的传质速率，实现水体有机染料污染物的高效去除。主要研究内容与结果如下：.（1）采用磺酸化改性制备两亲性石墨烯纳米片层（亲水性边缘和疏水性表面），利用聚乙烯醇的选择性交联来诱导石墨烯片层进行有序自组装，得到层状结构的石墨烯3D宏观体，其层间间距可调控；其内部有序排列结构为有机染料大分子在宏观体内的扩散提供了无障碍通道，相比无序结构，显著提高了对染料分子的吸附速率，并增加对染料污染物的吸附量。.（2）拓展小分子交联剂，利用甲酰胺作为交联剂兼成卷剂，辅助石墨烯片层在温和热处理和快速冷冻干燥条件下构筑由石墨烯纳米卷交织而成的3D宏观体；内部纳米卷结构避免了石墨烯片层的π-π堆叠，其开放的螺旋结构保证了染料分子的传输通道，从而大大提高有机染料分子的吸附速率；该过程同步在宏观体内引入一定量的N元素掺杂，使得宏观体对有机染料分子的π-π作用吸附贡献增强，导致石墨烯纳米卷3D宏观体对染料分子有超高吸附亲和力，以利于对低浓度有机污染物的吸附去除。.研究结果为设计和制备功能性石墨烯3D宏观材料，高效去除有机染料污染物提供理论依据与技术支撑。