We describe a novel method to produce monolithic, oriented, crystalline and highly porous coatings on solid substrates. By adopting the recently described liquid‐phase epitaxy (LPE) process developed to grow metal‐organic framework coatings (MOFs) on modified Au‐substrates to the spray method, we have prepared thick (μm) layers of several MOF types on modified Au‐substrates, including HKUST‐I and layer‐pillar MOFs. The spray method not only allows such SURMOFs to be grown much faster than with the LPE‐process but the dependence of layer thickness on the number of immersion cycles also provides valuable insights into the mechanism governing the layer‐by‐layer MOF formation process.
Via a facile ultrasound synthesis from nickel acetate and sodium hydroxide with ionic liquids as the solvent and template it is possible to obtain nano-b-Ni(OH) 2 of various dimensionalities depending on the reaction conditions with the ionic liquid (IL) being the most important factor. Scanning electron microscopy (SEM) imaging showed b-Ni(OH) 2 to form as nanosheets, nanorods and nanospheres depending on the IL. ILs with strong to moderate hydrogen bonding capability likelead to the formation of nanosheets whilst [Py 4 ][Tf 2 N] (butyl-pyridinium bis(trifluoromethanesulfonylamide)) leads to nanoparticles and [N 1888 ] [Tf 2 N] (methyltrioctylammonium bis(trifluoromethanesulfonylamide)) to nanorods. Subsequent calcination of the materials at elevated temperatures (285-425 C) leads to the conversion of b-Ni(OH) 2to NiO under preservation of the nanostructure. Scanning electron microscopy (SEM), X-ray diffraction (XRD), TG-DTA, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX) were used to observe the morphology, crystallinity, and chemical composition in more detail. Mesoporous NiO nanosheets obtained in [C 4 mim][Tf 2 N] possess an exceptionally high surface area of 141.28 m 2 g À1 and a pore volume of 0.2 cm 3 g À1 at 285 C. As a result of calcination at 425 C the surface area decreased to 92.84 m 2 g À1 , but the pore volume increased to 0.48 cm 3 g À1 . In addition, the product has an extraordinarily high saturation magnetization of 1.38 emu g À1 , a coercivity of 117 Oe and an excellent specific capacitance of 199.4 F g À1 which renders the material highly interesting for application in supercapacitors.
Despite their huge potential for efficient molecular separation, the fabrication of membranes from metal-organic frameworks (MOFs) remains a major challenge. The powders obtained by the conventional solvothermal MOF syntheses are difficult to process, and as a result the fabrication of well-performing, large-area MOF-based membranes is still awaiting success. The deposition of MOF thin films suited for membrane applications is demonstrated by employing a step-by-step spray method. This method can be scaled up to obtain industrially relevant membrane areas and a continuous process is also possible. The performance of sprayed HKUST-1-based membranes by the separation of a binary H /CO mixture is also demonstrated. Furthermore, this approach enables the control of the MOF film thickness, and thus controlling the permeance and the selectivity of the membrane.
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