Tailoring Surface Properties via Functionalized Hydrofluorinated Graphene Compounds. Issue 39 (7th August 2019) - Son, Jangyup
Abstract: A new compound material of 2D hydrofluorinated graphene (HFG) is demonstrated whose relative hydrogen/fluorine concentrations can be tailored between the extremes of either hydrogenated graphene (HG) and fluorinated graphene (FG). The material is fabricated through subsequent exposures to indirect hydrogen plasma and xenon difluoride (XeF2 ). Controlling the relative concentration in the HFG compound enables tailoring of material properties between the extremes offered by the constituent materials and in‐plane patterning produces micrometer‐scale regions with different surface properties. The utility of the technique to tailor the surface wettability, surface friction, and electrical conductivity is demonstrated. HFG compounds display wettability between the extremes of pure FG with contact angle of 95° ± 5° and pure HG with contact angle of 42° ± 2°. Similarly, the HFG surface friction may be tailored between the two extremes. Finally, the HFG electrical conductivity tunes through five orders of magnitude when transitioning from FG to HG. When combined with simulation, the electrical measurements reveal the mechanism producing the compound to be a dynamic process of adatom desorption and replacement. This study opens a new class of 2D compound materials and innovative chemical patterning with applications for atomically thin 2D circuits consisting of chemically/electrically modulated regions. Abstract : A new compound of hydrofluorinated graphene is demonstrated through sequential chemical functionalization of the surface of graphene. Patterning of distinct chemical regions and gradients in chemical concentration is demonstrated. The surface and electronic properties of hydrofluorinated graphene compounds are tailored by controlling the relative H/F concentration. This work provides a flexible platform for one‐atom‐thick 2D circuits with chemically/electrically modulated surfaces or lab‐on‐a‐chip for bioapplications.