Hoenig Eli, Strong Steven E, Wang Mingzhan, Radhakrishnan Julia M, Zaluzec Nestor J, Skinner J L, Liu Chong
Pritzker School of Molecular Engineering, University of Chicago, 5640 S Ellis Avenue, Chicago, Illinois 60637, United States.
Photon Science Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois 60439, United States.
Nano Lett. 2020 Nov 11;20(11):7844-7851. doi: 10.1021/acs.nanolett.0c02114. Epub 2020 Oct 6.
Restacked two-dimensional (2D) materials represent a new class of membranes for water-ion separations. Understanding the interplay between the 2D membrane's structure and the constituent material's surface chemistry to its ion sieving properties is crucial for further membrane development. Here, we reveal, and tune via covalent functionalization, the structure of MoS-based membranes. We find features on both the ∼1 nm (interlayer spacing) and ∼100 nm (mesoporous voids between layers) length scales that evolve with the hydration level. The functional groups act as permanent molecular spacers, preventing local impermeability caused by irreversible restacking and promoting the uniform rehydration of the membrane. Molecular dynamics simulations show that the choice of functional group tunes the structure of water within the MoS channel and consequently determines the hydrated interlayer spacing. We demonstrate that MoS membranes functionalized with acetic acid have consistently ∼92% rejection of NaSO with a flux of ∼1.5 lm hr bar.
重新堆叠的二维（2D）材料代表了一类用于水-离子分离的新型膜。了解二维膜的结构与组成材料的表面化学性质之间的相互作用及其离子筛分特性对于进一步开发膜至关重要。在这里，我们通过共价功能化揭示并调整了基于MoS的膜的结构。我们发现了在1 nm（层间距）和100 nm（层间介孔空隙）长度尺度上随水合水平而变化的特征。官能团充当永久性分子间隔物，防止由不可逆重新堆叠引起的局部不可渗透性，并促进膜的均匀再水合。分子动力学模拟表明，官能团的选择调节了MoS通道内水的结构，从而决定了水合层间距。我们证明，用乙酸功能化的MoS膜对NaSO的截留率始终约为92%，通量约为1.5 lm hr bar。
