Intermolecular interactions dictating adhesion between ZnO and graphite

Zinc oxide (ZnO) was recently demonstrated to strongly adhere to both pristine graphitic surfaces and oxidized surfaces; however, the bonding interaction between the two is unknown and has yet to be investigated. In this study, atomic force microscopy (AFM) liftoff in the dry state was performed with a ZnO coated AFM tip on highly oriented pyrolytic graphite (HOPG) such that the bonding interaction can be identified and used to design high strength interfaces. It is found that the ZnO film on the AFM tip becomes negatively charged after contacting an oxygen plasma treated HOPG surface, and once charged can strongly interact with other surfaces such as pristine HOPG through induced polarization to create high adhesive energy.