Metal-organic frameworks (MOFs) are porous crystalline materials built by metal clusters coordinated to organic ligands. Synthesis of MOFs has attracted considerable attention in recent decades, owing to its potential for a wide range of applications such as gas separation, dye adsorption, and catalysis, etc. The development of MOF membranes further enhances the potential of this type of material in industrial applications. Membrane fabrication methods, including in-situ growth, seeded secondary growth, interfacial growth, and vapor-phase deposition, have been widely studied. However, most of these methods either require a complicated synthesis procedure or are timeconsuming. Recently, the electrochemical synthesis has emerged as a highly promising approach to fabricate MOF membranes in a scalable manner, because it allows shorter synthesis time, milder synthesis condition, continuous reaction, and crystal self-healing. In this thesis, for the first time, an aqueously cathodic deposition (ACD) approach was developed to fabricate ZIF-8 type of MOF membranes without the addition of any supporting electrolyte or modulator. The fabrication process used 100% water as the sole solvent, and a low-defect density membrane was obtained in only 60 min under room temperature without any pre-synthesis treatment. The membrane exhibited superior performance in C3H6/C3H8 separation with C3H6 permeance of 182 GPU and selectivity of 142, making it sit at the upper bound of permeance versus selectivity graph, outperforming the majority of the published data up to 2019. Notably, this approach used an extremely low current density (0.13 mA cm-2) operated under a facile apparatus setup, enabling an attractive method for environmentally friendly, energy-efficient, and scalable MOF membrane fabrications. This work demonstrates the enormous potential of aqueously electrochemical deposition of the MOF membrane in future research.

Since the discovery of size-selective metal-organic frameworks (MOF) researchers have tried to manufacture them into gas separation membranes. ZIF-8 became the most studied MOF for membrane applications mainly because of its simple synthesis, good chemical and thermal stability, recent commercial availability and attractive pore size. The aim of this work is to develop convenient methods for growing ZIF thin layers on polymer supports to obtain defect-free ZIF membranes with good gas separation properties. We present new approaches for ZIF membranes preparation on polymers. We introduce zinc oxide nanoparticles in the support as a secondary metal source for ZIF-8 growth. Initially the ZnO particles were incorporated into the polymer matrix and later on the surface of the polymer by magnetron sputtering. In both cases, the ZnO facilitated to create more nucleation opportunities and improved the ZIF-8 growth compared to the synthesis without using ZnO. By employing the secondary seeded growth method, we were able to obtain thin (900 nm) ZIF-8 layer with good gas separation performance. Next, we propose a metal-chelating polymer as a suitable support for growing ZIF layers. Defect-free ZIF-8 films with a thickness of 600 nm could be obtained by a contra-diffusion method. ZIF-8 membranes were tested for permeation of hydrogen and hydrocarbons, and one of the highest selectivities reported so far for hydrogen/propane, and propylene/propane was obtained. Another promising method to facilitate the growth of MOFs on polymeric supports is the chemical functionalization of the support surface with functional groups, which can complex metal ions and which can covalently bond the MOF crystals. We functionalized the surface of a common porous polymeric membrane with amine groups, which took part in the reaction to form ZIF-8 nanocrystals. We observed an enhancement in adhesion between the ZIF layer and the support. The effect of parameters of the contra-diffusion experiment (such as temperature lower than room temperature and synthesis times shorter than 1 hour) on ZIF-8 membrane properties was evaluated. We could prepare one of the thinnest (around 200 nm) yet selective ZIF-8 films reported.