Lee Taemin, Kim Byeong-Su
Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea.
Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea.
ACS Appl Mater Interfaces. 2020 Mar 18;12(11):13116-13126. doi: 10.1021/acsami.9b20398. Epub 2020 Mar 5.
Graphene is a distinct two-dimensional (2D) material that provides a wide range of opportunities for membrane applications owing to its ultimate thinness, flexibility, chemical stability, and mechanical strength. In particular, chemically functionalized graphene oxide (GO) sheets containing amine and carboxylic acid groups facilitate solution-based processing and the formation of various internal structures depending on their properties such as the lateral dimension, defect density, and number of stacked layers. In this study, we designed and fabricated a multilayered GO membrane via the layer-by-layer assembly of two oppositely charged GO nanosheets and investigated the effects of the (1) lateral dimension of the GO nanosheet and (2) membrane thickness of the 2D nanochannels of the GO membrane on the ion permeation behavior. The correlations between the structural parameters of the GO membranes and ion diffusion kinetics were evaluated using the Nielsen model. The functional groups were selectively ionized by exposure to pH-adjusted water, which creates positive or negative net charges, resulting in an ion-selective permeability. The unique properties of the GO nanosheets play important roles in determining the trade-off between the membrane permeability and selectivity, leading to new applications of GO nanosheets as functional membranes.
石墨烯是一种独特的二维（2D）材料，由于其极薄、柔韧、化学稳定和机械强度高，为膜应用提供了广泛的机会。特别是，含有胺基和羧基的化学功能化氧化石墨烯（GO）片有助于基于溶液的加工，并根据其横向尺寸、缺陷密度和堆叠层数等性质形成各种内部结构。在本研究中，我们通过两种带相反电荷的GO纳米片的逐层组装设计并制备了多层GO膜，并研究了（1）GO纳米片的横向尺寸和（2）GO膜二维纳米通道的膜厚度对离子渗透行为的影响。使用尼尔森模型评估了GO膜的结构参数与离子扩散动力学之间的相关性。通过暴露于pH调节的水中使官能团选择性电离，从而产生正或负净电荷，导致离子选择性渗透。GO纳米片的独特性质在决定膜渗透性和选择性之间的权衡方面起着重要作用，从而导致GO纳米片作为功能膜的新应用。
