| AVS 65th International Symposium & Exhibition | |
| Surface Science Division | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Division Poster Session |
| Presenter: | Ann Lii-Rosales, Iowa State University and Ames Laboratory |
| Authors: | A. Lii-Rosales, Iowa State University and Ames Laboratory P.A. Thiel, Iowa State University and Ames Laboratory |
| Correspondent: | Click to Email |
Graphite, in the bulk, is known to form graphite intercalation compounds (GICs) with certain elemental metals, for example, rare earths, alkali metals, and alkaline earths. These metals can insert between graphene sheets and alter the magnetic or transport properties of graphite. While intercalation in the bulk of graphite has received much attention, considerably less has been paid to intercalation near the surface of graphite, underneath only one (or a few) graphene layers. First of all, can one trap metals just beneath the graphite surface? Do the surface-intercalated metals adopt different structures compared to their bulk counterparts? What is the driving force for such surface intercalation? These questions motivate our work.
The presentation will encompass strategies for achieving surface intercalation of metals in graphite. In short, we find that trapping metal atoms just beneath the graphite surface requires two specific conditions: (1) ion-induced defects on the graphite surface, and (2) elevated temperature during metal deposition. We find that this strategy works for a variety of metals, and the growth temperature is metal-specific. Results on dysprosium, copper and ruthenium will be presented. We use scanning tunneling microscopy to probe and characterize the surface intercalation. Based on experimental results and density functional theory, we find that the intercalated metal atoms at the graphite surface adopt much different structures compared to those in bulk GICs – “encapsulated” may be a better descriptor than “intercalated”. Furthermore, metals that are not known to form bulk GICs can be encapsulated at the graphite surface. Finally, we find that some of the metals are well protected from atmospheric oxidation by the graphene overlayer. Our synthetic strategy opens up a new avenue for metals to interact with the graphite surface, and to create novel surface nano-structures.