Templated growth of vertically aligned 2D metal–organic framework nanosheets†
The investigation of crystalline and amorphous metal–organic frameworks (MOFs) for gas capture & storage, catalysis, membrane separation, sensing, bio-entity protection and drug delivery is now widespread. The fabrication of two-dimensional MOFs, or metal–organic networks, is of particular interest, due to the greater accessibility of active sites in sub nanometer-thickness sheets, compared to 3D frameworks. However, the in situ assembly of 2D MOF nanosheets into practical devices, especially with controllable crystal orientations, remains challenging. This work demonstrates the use of a bottom-up templated growth technique to prepare a continuous, 2D MOF nanosheet coating layer, arranged with a vertical structural alignment. The deposition template consists of a layer of horizontally aligned 1D halloysite nanotubes, which act as nucleation sites for the 2D MOF and subsequently guide their vertical growth. Differential alignments of the 2D MOF layer result in the ability to tune the transfer behavior of different molecules, toward better device gas permeance and selectivity simultaneously.