Prof. Xixiang Zhang, honorary Professor  of CAMP-Nano , from King Abdullah University of science and Technologya , revisited CAMP-Nano on Oct 9, 2014. On the morning, Prof. Zhang gave a report named “Aberration-corrected TEM study of single layer graphene doping and edge decoration ” at room 215.

It is well known that functionalized graphene has been extensively studied with the aim of tailoring properties for gas sensors, superconductors, supercapacitors, nanoelectronics, and spintronics. A bottleneck is the capability to control the carrier type and density by doping.

In this talk. Prof. Zhang demonstrate that a two-step process is an efficient way to dope graphene: create vacancies by high energy atom/ion bombardment and fill these vacancies with desired dopants. Different elements (Pt, Co, and In) have been successfully doped in the single-atom form. The high binding energy of the metal-vacancy complex ensures its stability and is consistent with in situ observation by an aberration-corrected and monochromated transmission electron microscope.

In addition, he also introduced the interaction between single noble metal atoms and graphene edges by using the low-voltage TEM. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most  trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms.


Prof. Xixiang Zhang giving the report