Fabrication of MOF-5 membranes using microwave-induced rapid seeding and solvothermal secondary growth

Here we report the fabrication of continuous MOF-5 membranes via a secondary growth method. Densely packed MOF-5 seed layers on porous α-alumina substrates were rapidly prepared using microwave-induced thermal deposition (MITD) method. The MOF-5 seed layers were then solvothermally treated to grow into continuous MOF-5 membranes. The presence of a proton scavenging amine in precursor solutions during the secondary growth step was found to be critical to prevent the seed crystals from dissolving, yet enabling the growth of the MOF seed crystals into a continuous film. For the first time, preferentially oriented MOF-5 membranes were prepared by growing from oriented MOF-5 seed layers. Permeation results of MOF-5 membranes indicate Knudsen transport of small gas molecules, consistent with a previously reported result.