Thin films of stable metal-organic frameworks (MOFs) such as UiO-66 have enormous application potential, for instance in microelectronics. However, all-gas-phase deposition techniques are currently not available for such MOFs. We here report on thin-film deposition of the thermally and chemically stable UiO-66 in an all-gas-phase process by the aid of atomic layer deposition (ALD). Sequential reactions of ZrCl4 and 1,4-benzenedicarboxylic acid produce amorphous organic–inorganic hybrid films that are subsequently crystallized to the UiO-66 structure by treatment in acetic acid vapour. We also introduce a new approach to control the stoichiometry between metal clusters and organic linkers by modulation of the ALD growth with additional acetic acid pulses. An all-gas-phase synthesis technique for UiO-66 could enable implementations in microelectronics that are not compatible with solvothermal synthesis. Since this technique is ALD-based, it could also give enhanced thickness control and the possibility to coat irregular substrates with high aspect ratios.

Thin films of metal–organic frameworks (MOFs) are promising for a wide range of applications including membranes for separations and sensor materials in microelectronics.

Thin films of metal-organic frameworks (MOFs) prepared using all-gas-phase techniques such as atomic/molecular layer deposition (ALD/MLD) are emerging due to their potential for enabling suitable applications. Their high and specific porosity enables their use as membranes for separations and as a basis for sensors in microelectronics, provided that films can be made. The properties of such MOF materials can be tuned by choosing linker molecules that are functionalized with a variety of chemical groups. However, thin films of these functionalised MOFs have so far been prepared through wet based chemistries, which are difficult to combine with microelectronics and high aspect ratio structures. We here report on the thin film deposition of amino-functionalised UiO-66 through an all-gas-phase ALD/MLD process. By using amino-functionalised linkers, modulation by acetic acid to control the stoichiometry of the deposited film was no longer required, as opposed to the case in which unmodified terephthalic acid was used as a linker. The growth and properties of the films were characterised using an in situ quartz crystal microbalance (QCM), spectroscopic ellipsometry (SE), grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FTIR) and other techniques to obtain information on their growth dynamics and physical properties.

been demonstrated that MOFs not only are capable of efficiently capturing many Toxic Industrial Chemicals (TICs), but are also able to degrade the most toxic chemicals known to humankind, such as Chemical Warfare Agents (CWAs). These phenomena are important for development of more efficient and versatile technological solutions in the field of individual protective equipment (IPE) against TICs and CWAs, such as respirator filters and protective clothing. Moreover, it could well contribute to decontaminating capabilities. Thus, use of MOFs might offer a significant benefit of combining air purification and decontamination functionalities. In this respect, zirconium-MOFs (Zr-MOFs) are particularly good candidates due to their exceptional stability and excellent performance in catalytic degradation of CWAs, especially towards nerve agents (e.g., Sarin (GB), VX, tabun (GA), soman (GD), and their simulants). [2,[22][23][24]33] However, most commercially available and laboratory synthesized MOFs are in the form of fine powders, which hinders their practical use in many applications. For instance, in the case of respiratory protection devices, a fine powder sorbent would lead to a significant increase in airflow resistance across the filter. Analogously, the use of MOFs as a Metal-organic frameworks (MOFs) are a class of porous organic-inorganic solids extensively explored for numerous applications owing to their catalytic activity and high surface area. In this work MOF thin films deposited in a one-step, molecular layer deposition (MLD), an all-gas-phase process, on glass wool fibers are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and their capabilities towards toxic industrial chemical (TIC) capture and chemical warfare agents (CWA) degradation are investigated. It is shown that despite low volume of the active material used, MOFs thin films are capable of removal of harmful gaseous chemicals from air stream and CWA from neutral aqueous environment. The results confirm that the MLD-deposited MOF thin films, amorphous and crystalline, are suitable materials for use in air filtration, decontamination, and physical protection against CWA and TIC.

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