Metal organic frameworks (MOFs) are hybrid crystalline materials, exhibiting high specific surface areas, controllable pore sizes and surface chemistry.

Carbon nanotubes (CNTs) are nanoscale cylinders of graphene with exceptional properties such as high mechanical strength, high aspect ratio and large specific surface area. To exploit these properties for membranes, macroscopic structures need to be designed with controlled porosity and pore size. This manuscript reviews recent progress on two such structures: (i) CNT Bucky-papers, a non-woven, paper like structure of randomly entangled CNTs, and (ii) isoporous CNT membranes, where the hollow CNT interior acts as a membrane pore. The construction of these two types of membranes will be discussed, characterization and permeance results compared, and some promising applications presented.

Self-supporting carbon nanotube (CNT) Bucky-Papers have unique structural and surface properties which can be utilised in many applications. In this work we characterised pure selfsupporting CNT membranes, where CNTs were held together only by Van der Waals forces, and evaluated their potential and performance in direct contact membrane distillation. The membranes were found to be highly hydrophobic (contact angle of 113°), highly porous (90%), and to exhibit a thermal conductivity of 2.7 kW/m 2 •h. We demonstrate, as a proof of concept, that self-supporting CNT Bucky-Paper membranes can be used for desalination in a direct contact membrane distillation setup with 99% salt rejection and a flux rate of ~12 kg/m 2 *h at a water vapour partial pressure difference of 22.7kPa. Ageing of the membranes by delamination, factor limiting their performance, is also reported but work is currently done to address this issue by investigating composite material structures.

Photocatalytic conversion of carbon dioxide (CO) to useful products has potential to address the adverse environmental impact of global warming. However, most photocatalysts used to date exhibit limited catalytic performance, due to poor CO adsorption capacity, inability to efficiently generate photoexcited electrons, and/or poor transfer of the photogenerated electrons to CO molecules adsorbed on the catalyst surface. The integration of inorganic semiconductor nanoparticles across metal organic framework (MOF) materials has potential to yield new hybrid materials, combining the high CO adsorption capacity of MOF and the ability of the semiconductor nanoparticles to generate photoexcited electrons. Herein, controlled encapsulation of TiO and Cu-TiO nanoparticles within zeolitic imidazolate framework (ZIF-8) membranes was successfully accomplished, using rapid thermal deposition (RTD), and their photocatalytic efficiency toward CO conversion was investigated under UV irradiation. Methanol and carbon monoxide (CO) were found to be the only products of the CO reduction, with yields strongly dependent upon the content and composition of the dopant semiconductor particles. CuTiO nanoparticle doped membranes exhibited the best photocatalytic performance, with 7 μg of the semiconductor nanoparticle enhancing CO yield of the pristine ZIF-8 membrane by 233%, and methanol yield by 70%. This work opens new routes for the fabrication of hybrid membranes containing inorganic nanoparticles and MOFs, with potential application not only in catalysis but also in electrochemical, separation, and sensing applications.

We report the synthesis of the first continuous, inter-grown ZIF-8 membrane via the secondary growth method. ZIF-8 crystals were seeded and strongly anchored onto porous carbon nanotube bucky-paper supports and hydrothermally grown into a dense and continuous ZIF-8 network. The self-supporting hybrid metal organic framework membranes were characterized by scanning electron microscopy and shown to exhibit both a very homogeneous structure and a very smooth nanotube-metal organic framework interface. Gas adsorption (H 2 , CH 4 , CO 2 , N 2 ) and permeation (He, CO 2 , N 2 and Xe) tests were performed to evaluate the permeance of each gas and to predict the selectivity. The membranes were highly robust and sustained pressures as high as 500 kPa. Furthermore, the high selectivity of N 2 over CO 2 and Xe (33 and 163 respectively), shown by gas adsorption single gas permeation and mixed gas permeation clearly demonstrates the near defect-free nature of the membranes while the high hydrothermal stability of ZIF-8 makes these novel composites highly promising for water vapour saturated gas treatment.

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The potential of poly(acrylonitrile) electrospun membranes with tuneable pore size and fiber distributions were investigated for airborne fine-particle filtration for the first time. The impact of solution concentration on final membrane properties are evaluated for the purpose of designing separation materials with higher separation efficiency. The properties of fibers and membranes are investigated systematically: the average pore distribution, as characterized by capillary flow porometry, and thermo-mechanical properties of the mats are found to be dependent on fiber diameter and on specific electrospinning conditions. Filtration efficiency and pressure drop are calculated from measurement of penetration through the membranes using potassium chloride (KCl) aerosol particles ranging from 300 nm to 12 mm diameter. The PAN membranes exhibited separation efficiencies in the range of 73.8-99.78% and a typical quality factor 0.0224 (1 Pa À1 ) for 12 wt% PAN with nanofibers having a diameter of 858 nm. Concerning air flow rate, the quality factor and filtration efficiency of the electrospun membranes at higher face velocity are much more stable than for commercial membranes. The results suggest that the structure of electrospun membranes is the best for air filtration in terms of filtration stability at high air flow rate.