Continuous Crystalline Membranes of a Ni(II)-Based Pillared-Layer Metal-Organic Framework In Situ Grown on Nickel Foam with Two Orientations

The membranes of a pillared-layer structure Metal-Organic Framework (MOF), [Ni(HBTC)(4,4'-bipy)] (HBTC = 1,3,5-Benzenetricarboxylic acid, 4,4'-bipy = 4,4'-bipyridine), have been in situ fabricated on Nickel foam substrate. The orientations of MOF crystals in the membranes can be controlled by the molar ratio of ligand H3BTC to 4,4'-bipyridine. Scanning electron microscope images and powder X-ray diffraction patterns were used to characterize the membranes and confirm the orientations of their MOF layers. Control experiments have revealed that the presence of homologous metal element Nickel in both the MOF and the substrate and the presence of the neutral 4,4'-bipyridine in the reaction system are necessary for in situ growth of the well-intergrown MOF membranes. This work provides a successful example of directly growing continuous MOF layers on porous metallic substrate with desired orientations by a facile approach.