Chemiresistive Properties of Imprinted Fluorinated Graphene Films

The electrical conductivity of graphene materials is strongly sensitive to the surface adsorbates, which makes them an excellent platform for the development of gas sensor devices. Functionalization of the surface of graphene opens up the possibility of adjusting the sensor to a target molecule. Here, we investigated the sensor properties of fluorinated graphene films towards exposure to low concentrations of nitrogen dioxide NO₂. The films were produced by liquid-phase exfoliation of fluorinated graphite samples with a composition of CF_0.08, CF_0.23, and CF_0.33. Fluorination of graphite using a BrF₃/Br₂ mixture at room temperature resulted in the covalent attachment of fluorine to basal carbon atoms, which was confirmed by X-ray photoelectron and Raman spectroscopies. Depending on the fluorination degree, the graphite powders had a different dispersion ability in toluene, which affected an average lateral size and thickness of the flakes. The films obtained from fluorinated graphite CF_0.33 showed the highest relative response ca. 43% towards 100 ppm NO₂ and the best recovery ca. 37% at room temperature.