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.
Bibliographical noteFunding Information:
A.M.v.d.Z., J.S., and S.P.K. were supported in part by an NSF-MRSEC under Award Number DMR-1720633 and the NSF-CAREER award under Award Number CMMI-1846732. D.S. and S.H. were supported by the Global Research and Development Center Program (2018K1A4A3A01064272), the Basic Science Research Program (2017R1A2B2010123), and the Priority Research Center Program (2010-0020207) through the National Research Foundation (NRF) of Korea. G.-H.L. acknowledges supports from the Basic Science Research Program, the Creative Materials Discovery Program, and the International Research & Development Program through the NRF of Korea (2016M3A7B4910940, 2018M3D1A1058794, and 2019K1A3A1A25000267). K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and the CREST (JPMJCR15F3), JST. This work was carried out in part in the Micro and Nano Technology Laboratory and the Materials Research Laboratory Central Facilities at the University of Illinois. The authors acknowledge helpful discussions with Jaehyung Yu, Mohammad Abir Hossein, Elif Ertekin, Nadya Mason, and Pinshane Huang.
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering