层层组装构筑大面积氧化石墨烯基超薄，高通量及高截留率脱盐膜

Graphene-based materials are expected to impact the research and developments in separation membranes. However, the most commonly used vacuum filtration deposition method is hardly scalable. What’s more, the GO membrane exhibits hydration and instabilities in aqueous environment. These limitations severely slows down the applications of graphene-based materials in membrane filtration. In this proposal, we tackle the scalability of graphene-based materials following a bottom-up molecular self-assembly (MSA) method. The MSA-GO membrane is organized by the alternative growth of functionalized single-layer GO and intermediate molecular nanolayers. This preparation method, enabled by the flexibility of GO surface functionalization and the principle of molecular self-assembly, is a promising and scalable method to realize the controllability of pore structure, charge distribution and functionality distribution in the nanometer-level. We plan to use QCMD to analyze and monitor the step-wise growth of MSA-GO nanolayers. Based on the analysis tool, we investigate the relationship between MSA-GO membrane performance and the crucial parameters such as charge property, charge density, d-spacing, pore size distribution and defect size distribution. Further, a molecular transportation model will be developed combining Donnan exclusion, size exclusion and surface adsorption mechanisms. We expect the methodology adopted in this work will open a window for the application of graphene-based materials in membrane filtration.

石墨烯基材料在分离膜领域的应用前景令人期待。然而目前氧化石墨烯（GO）膜的制备仅限于实验室小规模，且在水溶液中稳定性较差，极大地限制了石墨烯基膜材料的应用。本项目从单层石墨烯视角出发，利用功能化单层石墨烯和薄膜分子层的交替生长，“自下而上”逐层构建改性石墨烯的纳米水通道体系（MSA-GO）。本制备方法充分利用单层石墨烯的表面可塑性功能化和分子自组装的设计原理，有望在纳米尺度实现调控截盐膜结构，孔道结构，电荷分布和功能基团分布。拟用QCMD对MSA-GO的生长速度，单层厚度等成膜过程关键参数进行分析和控制，通过GO的功能化改性和分子组装溶液条件，量化并调节表面电性，电荷密度，石墨烯层间距，孔径分布及缺陷尺寸等关键参数，考察其对MSA-GO分离性能的影响，建立基于“电荷排斥”，“孔径筛分”及“表面吸附”的协同传质模型。此项目为实现石墨烯基材料在膜领域应用突破提供关键方法和理论依据。

项目利用分子层层组装（抽滤、静电沉积、静电打印）等方式构筑大面积氧化石墨烯基截盐膜。经过正/负电荷的改性，石墨烯间的通道具有明显的空间排斥效应以及电荷排斥效应，加强了对盐分水合离子的分离。经过和聚酰胺的聚合耦合的作用，形成的MSA-GO膜具有很高的水通量(10-50 L m-2 h-1 bar-1), 最高的氯化钠截留率达到95%以上。同时，电荷组装的方式相比传统真空抽滤组装方式更为有效，有利于实现大面积石墨烯膜的制备。同时石墨烯特有的低粗糙度使石墨烯膜表面的粗糙度低，同时抗污染性能更佳。