School of Chemistry and Chemical Engineering, South China University of Technology, 510640, Guangzhou, China.
Institute of Physical Chemistry and Electrochemistry, Leibniz University of Hannover, Callinstrasse 3A, 30167, Hannover, Germany.
Nat Commun. 2018 Jan 11;9(1):155. doi: 10.1038/s41467-017-02529-6.
Molecular sieving membranes with sufficient and uniform nanochannels that break the permeability-selectivity trade-off are desirable for energy-efficient gas separation, and the arising two-dimensional (2D) materials provide new routes for membrane development. However, for 2D lamellar membranes, disordered interlayer nanochannels for mass transport are usually formed between randomly stacked neighboring nanosheets, which is obstructive for highly efficient separation. Therefore, manufacturing lamellar membranes with highly ordered nanochannel structures for fast and precise molecular sieving is still challenging. Here, we report on lamellar stacked MXene membranes with aligned and regular subnanometer channels, taking advantage of the abundant surface-terminating groups on the MXene nanosheets, which exhibit excellent gas separation performance with H permeability >2200 Barrer and H/CO selectivity >160, superior to the state-of-the-art membranes. The results of molecular dynamics simulations quantitatively support the experiments, confirming the subnanometer interlayer spacing between the neighboring MXene nanosheets as molecular sieving channels for gas separation.
具有足够且均匀纳米通道的分子筛膜可以打破渗透性-选择性权衡，有利于节能型气体分离，而新兴的二维（2D）材料为膜的发展提供了新途径。然而，对于 2D 层状膜，在随机堆叠的相邻纳米片之间通常会形成无序的层间纳米通道，这不利于高效分离。因此，制造具有高度有序纳米通道结构的层状膜以实现快速和精确的分子筛分仍然具有挑战性。在这里，我们报告了具有取向和规则亚纳米通道的层状堆叠 MXene 膜，利用 MXene 纳米片上丰富的表面终止基团，其气体分离性能优异，H2 渗透性>2200 Barrer，H2/CO2 选择性>160，优于最先进的膜。分子动力学模拟的结果定量支持了实验，证实了相邻 MXene 纳米片之间的亚纳米层间距作为气体分离的分子筛通道。
