Fig. 1. Fabrication of vertically aligned MOF nanosheet layer on hydrogel membranes.

a Schematic of the membrane fabrication process. Hydrogel solution was blade-coated to form the CT/PVA substrate and immersed into the precursors for the directional growth of MOF nanosheets. b Schematic of the dual effects of PEG in the synthesis of MOF-CT/PVA, acting as both a crosslinking (hydrogel phase, blue) and surfactant agent (MOF phase, pink). PEG selectively attaches to the nanocrystals during the anisotropic growth of Zn-TCPP. c Vertically aligned nanostructure on the surface and cross-section of MOF-CT/PVA after bending and flipping tests. d Rigorous bending and flipping tests of MOF-CT/PVA. e AFM images and thickness of the MOF nanosheets (white dash line) detached from MOF-CT/PVA.