Preparation and properties of graphene oxyfluoride films

Graphene-based films are promising candidates for filtration and separation applications due to their modulable properties, including composition, hydrophobicity, and stability. In this study, we present the preparation of graphene oxyfluoride films by gas-phase fluorination of graphene oxide layers under a dynamic flow of F2/N2 gas (0.35/0.65 volume ratio) at different reaction temperatures (15 °C, 100 °C, and 200 °C). The resulting films exhibited a stable morphology, maintaining their densely packed structure and parallel arrangement of fluorinated sheets. By varying the reaction temperature, we were able to control the carbon, oxygen, and fluorine compositions, as well as the surface functional groups of the fluorinated films. Water stability tests revealed that the films fluorinated at 100 °C displayed the highest stability in water compared to other film types. This enhanced stability can be attributed to the formation of strong covalent C–F bonds within the film. Furthermore, the graphene oxyfluoride membranes exhibited water vapor permeability similar to that of the original graphene oxide membrane, ranging from 8.7 to 9.1 LMH/bar. These findings demonstrate the potential of graphene oxyfluoride membranes as versatile materials for various filtration and separation applications, where the composition and stability of the membrane can be tailored to specific requirements.