Defectous UiO-66 MOF Nanocomposites as Reactive Media of Superior Protection against Toxic Vapors.

The composites of UiO-66 with nanographite or oxidized graphitic carbon nitride nanospheres (∼10 wt %) were synthesized and used as CEES decontamination media from a vapor phase. The materials were characterized using XRD, nitrogen adsorption, SEM, potentiometric titration, FTIR, and thermal analysis. The results showed a marked improvement of the detoxification capability against the vapors of CEES compared to those of pristine UiO-66, either in terms of the amount adsorbed or surface reactivity. The maximum weight uptake for the composites reached 632 mg g-1, which was higher than that on UiO-66. The improved adsorption and catalytic activity were linked to the new interface between the modifiers and MOF units/defects, which provided additional active sites formed as a result of modifiers' surface groups acting as MOF linkers. The morphology and porosity were also altered, positively affecting the sites' accessibility and their dispersion in the MOF particles. Dehydrohalogenation and oxidation were the predominant pathways of the composites' surface reactivity. The detoxification mechanisms involving CEES vapor-UiO-66 surface interactions differ from those reported for CEES liquid/dissolved liquid-UiO-66 interactions, and dehydrohalogenation, fragmentation, and oxidation predominate.