| AVS 60th International Symposium and Exhibition | |
| Graphene and Other 2D Materials Focus Topic | Tuesday Sessions |
| Session GR+AS+EM+MI+MN-TuM |
| Session: | Optical, Magnetic, Mechanical and Thermal Properties of 2D Materials |
| Presenter: | L. Li, University of Wisconsin Milwaukee |
| Authors: | Y. Liu, University of Wisconsin Milwaukee M. Weinert, University of Wisconsin Milwaukee L. Li, University of Wisconsin Milwaukee |
| Correspondent: | Click to Email |
We perform atomic resolution imaging of vacancy defects in graphene using non-contact atomic force microscopy, and directly determine their charges by local contact potential difference measurement. We observe reconstruction, healing, and merging of vacancy defects. Combined with first-principles calculations, we further show that vacancy defects are typically positively charged, while H adsorbates at these sites can produce negatively charged structures, and their charge states are not necessarily integer-valued. These results provide new insights into the stability of charged vacancy defects in graphene, as well as the functionalization of graphene for chemical sensing and catalysis, and underline the tunability of these functions by controlling the size and doping of vacancy defects.