Improving water transport through <scp>sub‐nanometer</scp> channels by alternating <scp>hydrophilic–hydrophobic</scp> patterns
Fang Xu, Linfeng Lei, Cheng Lian, Zhi Xu
Abstract
Abstract Hydrophilicity is key factor to sub‐nanometer channels for water transport. However, how to effectively integrate the respective advantages of hydrophilicity and hydrophobicity to realize ultrafast water transport at the sub‐nanometer scale is still confusing. By using sub‐nanometer channels formed by two‐dimensional covalent organic frameworks as typical models, we herein demonstrate that alternating hydrophilic–hydrophobic patterns in channels are capable of significantly improving water transport. Alternatingly stacking hydrophilic and hydrophobic monolayers is testified to be energetically favorable to directly piling their multilayers. Meanwhile, alternatingly‐stacked hydrophilic–hydrophobic multilayers are able to achieve much higher water permeability than individual hydrophilic or hydrophobic multilayers. The effect of framework flexibility is also investigated. The exceptional performances benefit from the perfect balance between excellent wettability of hydrophilicity and low friction of hydrophobicity. In order to give full play to the synergistic advantages, the thickness of hydrophobic patterns spaced by hydrophilic ones should be less than 1 nm.