Two-dimensional heterogenous channels incorporated by enhanced-surface hydrophilic hollow ZIF-8 nanocrystals for ultrafast water permeation

Two-dimensional (2D) interlayer confined channels of graphene oxide (GO) membrane and their potential for ultrafast water molecules transport behavior have drawn substantial interest for advanced water-related membrane separation process. However, the water transfer pathways along the edge-to-edge slits to interlayer channels of adjacent GO nanosheets are still very tortuous, leading to low-efficiency water permeation. Herein, we designed and prepared hollow zeolitic imidazolate framework-8 nanocrystals with enhanced hydrophilic surface (DP@HZIF-8), and then they were incorporated into GO membrane to introduce more nanofluidic channels. More importantly, the enhanced-surface hydrophilicity could well capture water molecules and make them diffuse along the porous multi-pathways of DP@HZIF-8 and interlayer channels of GO, further reducing mass transfer resistance and improving water transfer efficiency under highly-water chemical potential driving force in membrane microregion. As-prepared DP@HZIF-8/GO membrane on polyethersulfone (PES) substrate with optimum structure showed the pure water flux as high as 32.11 kg m⁻² h⁻¹ at 323 K, and meanwhile exhibited superior pervaporation dehydration performance of butanol/water mixture with total flux of 5.32 kg m⁻² h⁻¹ and separation factor of 3567 at 343 K, respectively. This work strengthens the understanding of high-efficiency water transport along multi-dimensional heterogenous channels in advanced 2D separation membranes.