Engineering artificial water channels into ionic covalent organic framework membranes towards efficient desalination

Artificial water channels (AWCs), inspired by biological aquaporins, feature unique directional transport pathways and distinct water permselectivity. However, processing discrete AWCs superstructures into membranes is quite challenging due to the weak intermolecular interactions and poor membrane-forming capability. Herein, we applied a mixed-dimensional self-assembly strategy to combine AWCs with ionic covalent organic framework (COF) nanosheets, resulting in a hierarchical structure of AWCs inserting into the interlayer of COF membranes. AWCs and COF nanosheets exhibited excellent compatibility, enabling AWCs-COF membranes to achieve highly efficient water permeation with significant Å-scale ionic sieving. The optimal membranes manifest a water permeance of 5.32 L m^-2 h⁻¹ bar⁻¹ and a NaCl rejection of 97.7 %, superior to most reported desalination membranes. Furthermore, AWCs-COF membranes display high stability with the performance decline below 5 % during 14-day filtration. This work explores the collaborative optimization of AWCs and two-dimensional materials, thereby inspiring the rational design of high-performance desalination membranes.