Adsorption properties in high optical quality nanoZIF-8 thin films with tunable thickness

Abstract

We report processing of a thin film by chemical solution deposition of a microporous ZIF-8 nanoparticle dispersion. By using the drain and capillary regimes involved in the dip-coating process, we tuned the thickness of the films from 40 nm to 1 µm and controlled the packing of the nanoparticles on the substrate. The high optical quality thin films show a dual hierarchical porous structure from the micropores of the framework and the mesoporous interparticular voids. Moreover, vapor sorption properties of the microporous ZIF-8 based thin films have been evaluated by ellipsometric porosimetry. The hydrophobic films show alcohol, THF and hydrocarbon adsorption. Experiments for isopropanol/water separation have been carried out and the selective adsorption of the alcohol versus the water makes these thin films good candidates for vapor sensors.