MXene Membranes Inserted with Tannic Acid Etched MOF Nanocrystals for Ultrafast Water Permeation: Elucidating the Water Transport Mechanism in Nanoconfined Interlaminar Channels

Utilizing pore and interlayer engineering within nanoconfined interlaminar channels represents an ingenious approach to design highly permselective MXene (Ti₃C₂T_X) membranes. Herein, the tannic acid (TA) etched ZIF-8 (TZIF-8) nanocrystals with hollow structures were effectually inserted into the interlayer spacing of MXene membranes. First, the density functional theory (DFT) results demonstrated the reaction mechanism between TA and ZIF-8. Then, the underlying mechanism of enhanced water-adsorptive properties for MXene/TZIF-8 membrane was due to the higher binding energy of water/TZIF-8 system than that of water/ZIF-8 system, elucidated by molecular dynamic simulation. Furthermore, the low mass transfer resistance and abundant mass transfer pathways of the MXene/TZIF-8 membrane were comprehensively proved by various experimental conclusions, characterizations and simulation calculations. As a result, the optimal MXene/TZIF-8 membrane exhibited high water permeance and concurrently satisfactory separation efficacy toward various oil/water emulsions. This work is anticipated to deepen the comprehension of high-efficiency water transport along interbedded nanochannels in MXene membranes.