CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences, 100 Haike Road, Shanghai, 201210, China.
Department of Electronic Information Materials School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China.
Adv Mater. 2018 Apr;30(16):e1705775. doi: 10.1002/adma.201705775. Epub 2018 Mar 14.
The poor mechanical strength of graphene oxide (GO) membranes, caused by the weak interlamellar interactions, poses a critical challenge for any practical application. In addition, intrinsic but large-sized 2D channels of stacked GO membranes lead to low selectivity for small molecules. To address the mechanical strength and 2D channel size control, thiourea covalent-linked graphene oxide framework (TU-GOF) membranes on porous ceramics are developed through a facile hydrothermal self-assembly synthesis. With this strategy, thiourea-bridged GO laminates periodically through the dehydration condensation reactions via NH and/or SH with OCOH as well as the nucleophilic addition reactions of NH to COC, leading to narrowed and structurally well-defined 2D channels due to the small dimension of the covalent TU-link and the deoxygenated processes. The resultant TU-GOF/ceramic composite membranes feature excellent sieving capabilities for small species, leading to high hydrogen permselectivities and nearly complete rejections for methanol and small ions in gas, solvent, and saline water separations. Moreover, the covalent bonding formed at the GO/support and GO/GO interfaces endows the composite membrane with significantly enhanced stability.
氧化石墨烯（GO）膜的机械强度较差，这是由于层间相互作用较弱所致，这对任何实际应用都是一个重大挑战。此外，堆叠 GO 膜的固有但较大的 2D 通道导致小分子的选择性较低。为了解决机械强度和 2D 通道尺寸控制问题，通过简便的水热自组装合成，在多孔陶瓷上开发了硫脲共价连接的氧化石墨烯框架（TU-GOF）膜。通过这种策略，通过 NH 和/或 SH 与 OCOH 以及 NH 对 COC 的亲核加成反应，硫脲桥连的 GO 层周期性脱水缩合，导致 2D 通道变窄且结构明确，这是由于共价 TU 键的小尺寸和脱氧过程所致。所得的 TU-GOF/陶瓷复合膜对小分子具有出色的筛分能力，在气体、溶剂和盐水分离中，对甲醇和小离子具有高的氢渗透选择性和几乎完全的排斥。此外，在 GO/载体和 GO/GO 界面形成的共价键赋予了复合膜显著增强的稳定性。
