| AVS 66th International Symposium & Exhibition | |
| 2D Materials | Thursday Sessions |
| Session 2D+AS+BI+HC+MN+NS+PS+SS+TL-ThA |
| Session: | Surface Chemistry, Functionalization, Bio, Energy and Sensor Applications |
| Presenter: | Jangyup Son, University of Illinois at Urbana-Champaign |
| Authors: | J. Son, University of Illinois at Urbana-Champaign N. Buzov, University of California at Santa Barbara S. Chen, University of Illinois at Urbana-Champaign D. Sung, Sejong University, Republic of Korea H. Ryu, Seoul National University, Republic of Korea J. Kwon, Yonsei University, Republic of Korea S. Kim, University of Illinois at Urbana-Champaign J. Xu, University of Illinois at Urbana-Champaign S. Hong, Sejong University, Republic of Korea W. King, University of Illinois at Urbana-Champaign G.H. Lee, Seoul National University, Republic of Korea A.M. van der Zande, University of Illinois at Urbana-Champaign |
| Correspondent: | Click to Email |
Mixing compounds or alloys is an important process to tailor or enhance the intrinsic properties of materials such as chemical reactivity, mechanical strength, and electronic structure. In nanosystems, such as two-dimensional (2D) materials like graphene, transition metal dichalcogenides (TMDCs), and hexagonal boron nitride (hBN), where there is no distinction between the surface and the bulk, mixing of elements is also an important tool for tailoring the interaction of the material with its environment. A successful strategy for manipulating the chemical structures of 2D materials is the chemical functionalization of graphene with single elements such as H, O, N, and F. Yet, an even wider parameter space is possible by combining these functionalization species to produce ternary functionalized graphene compounds.
Here we present a new strategy for producing functionalized graphene compounds through the systematic control of the ratio between adatoms. We demonstrate tailored hydrofluorinated graphene (HFG) compounds via the sequential exposure of graphene to low-energy hydrogen plasma and xenon difluoride (XeF2) gas. We demonstrate reversible switching of the surface between completely hydrogenated graphene (HG) and fluorinated graphene (FG) as well as the intermediate ratio between two extremes. Moreover, we demonstrate pattern the surface functionalization on a single chip into chemically distinct materials (graphene, FG, HG, and HFG compounds).
Finally, with these patterned structures, we demonstrated tailoring of the surface and electronic properties of the 2D materials. First, the patterned structures enable direct comparisons of the relative surface properties such as wettability and surface friction. Additionally, the electrical properties of functionalized graphene compounds showed unusual recovery of electrical conductance during the partial transformation of FG to HFG, due to initial removal of existing F adatoms when exposed to hydrogen plasma. This study opens a new class of 2D compound materials and innovative chemical patterning that can lead to atomically thin 2D circuits consisting of chemically/electrically modulated regions.