| AVS 61st International Symposium & Exhibition | |
| 2D Materials Focus Topic | Tuesday Sessions |
| Session 2D+AS+BI+PS+SS-TuM |
| Session: | 2D Materials: Surface Chemistry, Functionalization, Bio and Sensor Applications |
| Presenter: | Xin Liu, University of Pennsylvania |
| Authors: | X.-Z. Liu, University of Pennsylvania Q. Li, University of Pennsylvania S.P. Kim, Brown University V.B. Shenoy, University of Pennsylvania P.E. Sheehan, Naval Research Laboratory J. Robinson, Naval Research Laboratory R.W. Carpick, University of Pennsylvania |
| Correspondent: | Click to Email |
The chemical functionalization of graphene can alter its electronic, chemical, mechanical, and tribological properties. Here we employ atomic force microscopy (AFM), Raman microscopy, and molecular dynamics (MD) simulations to show that friction can be fine-tuned by chemically modifying graphene. Although bulk fluorinated graphite has a very low surface energy, our experiments and simulations both show that friction between nanoscale tips and FG is up to 9 times higher than that for pristine graphene. The ability to resolve an ordered lattice in atomic stick-slip friction measurements also diminishes with greater fluorination, indicating that the fluorinated graphene is disordered. Our observation suggests that AFM friction measurements provide a sensitive local probe of the degree of fluorination of graphene. Motivated by MD simulations, we propose that the dramatic enhancement of friction results from increased corrugation of the interfacial potential due to the strong local charge concentrated at fluorine sites, consistent with the Prandtl-Tomlinson model.