Abstract
We report the controlled synthesis of thin films of prototypical zirconium metal–organic frameworks [Zr6O4(OH)4(benzene-1,4-dicarboxylate-2-X)6] (X = H, UiO-66 and X = NH2, UiO-66-NH2) over the external surface of shaped carbonized substrates (spheres and textile fabrics) using a layer-by-layer method. The resulting composite materials contain metal–organic framework (MOF) crystals homogeneously distributed over the external surface of the porous shaped bodies, which are able to capture an organophosphate nerve agent simulant (diisopropylfluorophosphate, DIFP) in competition with moisture (very fast) and hydrolyze the P–F bond (slow). This behavior confers the composite material self-cleaning properties, which are useful for blocking secondary emission problems of classical protective equipment based on activated carbon.
Highlights
Despite the international prohibition of the use and stockpiling of chemical warfare agents (CWAs), there is a high threat of exposure to highly toxic chemicals, as a consequence of destabilizing group actions
Temptative studies with nitric acid (HNO3) and hydrogen peroxide (H2O2) lead to the selection of the latter as it does not damage the activated carbon (AC) porosity, as proven by N2 adsorption measurements. This oxidative treatment led to an increase in oxygen groups on the surface as confirmed by X-ray photoelectron spectroscopy (XPS) analysis
The controlled layer-by-layer growth of crystalline metal−organic framework (MOF) thin films over AC shaped substrates can be regarded as a suitable approach for the fabrication of advanced self-cleaning porous materials
Summary
Despite the international prohibition of the use and stockpiling of chemical warfare agents (CWAs), there is a high threat of exposure to highly toxic chemicals, as a consequence of destabilizing group actions. Current protective systems against CWAs take advantage of high porosity, hydrophobicity and easy shaping of activated carbon (AC) adsorbents.[4,5] AC-based protective systems lack safety, as a small fraction of the adsorbed contaminant molecule can desorb from the pore surface (a phenomenon called secondary emission) and subsequently contaminate the user. In this regard, a variety of porous metal−. The resulting MOF@AC composites behave as self-cleaning materials in the capture and degradation of the organophosphate nerve agent simulant diisopropyl fluorophosphate (DIFP) blocking the secondary emission problems of traditional AC-based protective filters
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